Will Solar Power From Detached Garage Really Save Money?
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Sun is a never ending source of clean energy. Sure, you know that. But did you know that Solar Power from your Detached Garage can really save money?
Unless you are a scientist or an engineer working in the energy sector, you may have limited knowledge about how solar power works and saves money for you.
In this post I will explain the basics of solar power in simple easy to understand language. This will be enough for you to understand the solar power system and estimate the rating you need, costs involved, tax benefits, energy cost savings, etc.
You will be able to figure out the “Return On Investment” (ROI) of getting Solar Power from Detached Garage.
How Much Money can you Save using Solar Power from Detached Garage?
You can save 600 per year on an average by installing a 3 kW Solar Power System on a Detached Garage roof. The system will generate 4000 kWh of electricity per year. The garage should have 200-240 square feet of south facing roof to accommodate 10-12 solar panels. The payback period is 7-10 years and the ROI is in the 10-30% range.
The numbers are indicative estimates. Several factors need to be considered for specific calculations. Read the blog for a better understanding.
Can you put Solar Panels on Detached Garage?
You definitely can put solar panels on your detached garage roof, if it gets plenty of sunlight.
Installation of Solar Panels on top of a detached garage that has a sufficiently large roof facing the sun most of the day could even make the detached garage power independent from your home. The solar panels can generate electricity during day and store it in batteries for use at night.
The power requirement of a detached garage is not much. The power generated from the solar panels on the detached garage will be able to meet the requirement. With solar panels you can even insulate and add heating to a detached garage and make it more comfortable.
How does Home Solar Power work?
Home Solar Power, in this case the Garage Solar Power, works by using technology to harness the energy in the sunlight and converting it to electricity.
The electricity can be used to run the essentials such as the Garage Door Opener Motor and the Garage Door Lights. It can be used to run climate control and ventilation equipment such as the exhaust fans and split mini air conditioners or the radiant heating to keep the garage comfortable and livable.
Sun as the Power Source
The sun is huge and at its core is hydrogen. The hydrogen is at extremely high temperatures pressure because of the immense size gravity of the sun. The result is that the hydrogen atoms meld together to form helium atoms through a process called “nuclear fusion”
Nuclear fusion releases a lot of energy. When I say, a lot, it is really A LOT!!
“Every 1.5 millionths of a second, the Sun releases more energy than all humans consume in an entire year.”
Put another way, the amount of solar energy falling on earth is 10,000 times more than what humans need. (Source: NOAA)
What is the Purpose of Photovoltaic Cell?
Scientists Engineers have figured out a way by which the sunlight is used to knock electrons free from atoms, generating a flow of electricity. They call this process “photovoltaic”.
A solar panel is nothing but an array of photovoltaic (PV) cells, which is basically a sandwich made up of two slices of semiconducting material, usually silicon.
The electricity from each cell is collected and channeled to an inverter. The inverter converts DC to AC which can be used or stored.
What are the Main Components of a Solar Power System?
A residential Solar Power System can be “grid-tied” or “off-grid”. The off-grid system has the following main components.
The number of panels required depends on the total energy kW requirement and the energy that each panel can generate.
Most residential solar power systems use between 250-325 watt solar panels. So a 10kW solar power system will have between 30-40 solar panels.
Each solar panel has an inverter that converts the DC electricity generated to AC electricity required. The inverter is often integrated into the solar panel, making the installation process a lot easier.
This is the frame that holds the photovoltaic cells and the inverter into a solar panel. This needs to be light and sleek.
Complete electricity generation and consumption analysis available from the EnergyLink app.
Energy Storage Batteries
The electrical energy generated during the day when the sun is shining is stored in an efficient battery for use in the night to, say, power the lights.
Technically speaking, this would not be necessary in a grid-tied system. In reality it is a good practice to have it as a backup for unexpected power outages. The battery can also kick in when demand on the grid is high (which means the rates are high!)
Power, Energy Consumption Area Calculation Guide
Every electrical appliance, right from a light bulb to a refrigerator, in your house comes with a power rating. For example an LED bulb may be rated 15W while a refrigerator may be rated 150W.
To calculate the actual energy consumption, you need to multiply the power rating of an appliance with the number of hours the appliance is in use, A 15W LED bulb switched on for 5 hours would consume 75Wh of energy.
To estimate the energy requirement of your home, you will need to estimate the usage time of each appliance, multiply that by its power rating and then add up all the energy consumption estimates across every appliance.
Rating of Solar Power System
This can be very tedious. An easier way is to check your electricity bill for the last 12 months. Utility bills will give you the energy consumed in kWh along with the amount.
It is best to take a 12 month period as the energy consumption will have a seasonality. For estimating the required power rating of the solar power system, use the maximum, rather than the average, monthly consumption.
Just For Your Information
In 2019, the average annual electricity consumption for a U.S. residential utility customer was 10,649 kWh, an average of about 877 kWh per month.
If the maximum monthly consumption is 900 kWh then the daily consumption would be 30 kWh. Assuming that the solar panels on the detached garage can get direct sunlight for 5 hours in a day, the power rating of the solar power system on the detached garage should be 6 kW.
This calculation assumes 100% efficiency. In reality, efficiencies are lower and you would probably need a 8kW system.
The amount of sunlight you can get is location dependent. You would need a much larger system in Alaska as compared to one in Texas, for example.
A solar panel takes up about 20 square foot of roof space. If it is rated at 300 W, then a 6 kW (that is 6000 W) solar power system would use 20 panels (6000 W divided by 300 W) and would need 400 square feet (20 X 20) of roof space.
Keep in mind that these are simplistic calculations, just to illustrate the method.
In reality, many other factors such as roof pitch, panel efficiency, location etc. have to be incorporated in the calculation.
Which is Better? Grid-Tied or Off-Grid Solar Power System?
An important decision that you will need to make is whether your Solar Power System will be Grid-Tied or Off-Grid.
In a grid-tied system the energy generated is stored in the power grid, whereas in the off-grid system the energy generated has to be stored in batteries.
- Lower initial cost as storage battery is not required
- Can sell additional energy to the grid
- Assurance of power from the grid if your requirement is higher
Often even a grid-tied system has a battery storage as a backup, in case of unexpected power outages or extreme weather.
If your house is far from the grid then an off-grid system may be more cost effective and better for you.
How Much does a Solar Power System for a Detached Garage Cost?
The cost of a Solar Power System for a Detached Garage depends mainly on the power rating and whether the system will be grid-tied, grid-tied with battery backup or off-grid.
Solar Power System cost should include all costs; that is solar panels, inverters, panel mounting, circuit breakers, wiring, storage batteries, etc., labor costs, permits inspections.
can and do vary across locations. This is partly based on the amount of sunlight a state gets. The more the sunshine hours the less the number of solar panels required for the same kWh energy generation.
also depend on quality and the guarantees that manufacturers give. It is not advisable to go for the lowest price as it is a long term investment.
The good news is that the initial costs of solar power systems have been steadily declining. It has dropped from 6.00 per watt in 2010 to 2.50 in 2020.
How to Get a Building Permit for a Solar System?
Before you can put up a solar power system on your detached garage you need to get a building permit from the local authorities.
The solar permit is only granted after submission of drawing sets for rooftop installations. Engineering drawings with detailed measurements for obstructions, fire setbacks, array locations, conduit path, junction boxes, mounts and rails, must be submitted and an approval obtained.
DISCLAIMER: I am not an employee or affiliate of Go Green Solar or SUNPOWER. I will not have any financial or other benefits if you buy their products or use their services. The information presented here is to better inform my readers and to be help them in their decision making.
If your home is in California or a nearby state, why not check out Go Green Solar. Their solar kits come with a guarantee that you will receive a permit to install your system or your money back.
They will make sure you have all the necessary components and instructions to get your system up and running. They have thousands of satisfied customers and hundreds of testimonials!
Check out Solar Reviews to get an idea of the cost by state, by brand and by system size. The site also has a solar panel cost calculator, that you can use for your specific requirements.
Are there Tax Breaks for Installing Solar Panels?
Here is a link that can be super helpful for understanding and claiming the Federal Tax:
Federal Solar Tax Credit (What It Is How to Claim It for 2023)https://www.ecowatch.com/solar/incentives/federal-tax-credit
In addition to the Tax Credit from the Federal Government, most states have incentives that can further lower your cost or provide some other value. For example New Jersey allows 100% exemption from Sales Tax.
Please check for your state and location.
What is the Best Way to Finance Solar Panels?
Some companies offer integrated solar power system solutions. This includes features like a 25 year guarantee on all components and a financing option with 0% down payment. They can also adjust your eligible Tax Credit from the initial price.
- The SunPower Equinox® system with SunVault™ Storage is the only home solar storage system designed by one company. From record-breaking panels to seamless energy storage, every component is designed to work together perfectly.
- The warranty covers your whole system (not just the panels). They have got you covered for 25 years – including performance, labor and parts.(conditions may apply).
- The SunPower Equinox® system features unrivaled performance with the most efficient solar panels on the market.
- Their experts do the legwork. They are a national brand with a large network of dealers installers.
- SunPower offers three flexible payment options, so you can choose what’s right for you—cash, lease or loan. And you may qualify for federal solar tax credits with a cash purchase or our popular loans.
Why put Solar Panels on a Detached Garage Roof?
Solar panels can be placed anywhere, as long as they get maximum exposure to sunlight. The detached garage may often be a good choice for a residential solar power project.
Quite often the location of a detached garage is ideal. The roof may not be under any shade. This ensures that the panels are exposed to the sunlight for longer periods.
The electricity produced by a solar panel is directly proportional to the time it is exposed to direct sunlight. Put another way, the size of the solar power system can be reduced if the exposure time can be reduced.
Roof Style Pitch
A building roof can be a gable roof, a gambrel roof or a hip roof. Generally detached garages have gable roofs with a low pitch of 3/12 or 4/12. The main house usually has a hip roof with a higher pitch ranging from 4/12 and 9/12.
For the same floor area a gable roof will offer more space to put panels than a hip roof. A standard 2 car garage has a floor area of 400 (20’X20’) square feet. Each of the gable roofs will have an area of around 206 square feet, enough to put 10 solar panels. That can power a 3 kW solar power system.
Now that may not be enough but it helps. Other panels can be put on parts of the house roof.
If you think that solar panels on your roof reduce the curb appeal, then putting some of the panels on the detached garage roof will certainly help. Since the garage doors will likely face the street, the garage roof will be perpendicular to the street.
The solar panels will be less visible. It also helps that the garage roof is both low and at a lower pitch.
Read my earlier blog post The Best Location For Detached Garage Next To House (Practical!) if you are planning on a new detached garage.
Convenient Battery Location
The batteries of the solar power system can be conveniently located within the garage. Quite often it is difficult to find a convenient place for them inside the house.
Add a Carport
Is your garage so full of stuff that your cars need to be parked outside? Why not add a carport attached to the detached garage and place some of the solar panels on it?
You will be killing two birds with one stone.
Check out my earlier blog post What You Need To Know About Carport Attached To The Garage for more information on carports.
DISCLAIMER: What Is the Safest Way to Handle Electrical Wires?
This post is for information only. I strongly recommend that all electrical work should be entrusted to licensed professional electricians. In case you do decide to do some of the work yourself, make sure that:
“Treat all electrical wiring, even “de-energized” ones as if it is live, unless it has been locked out and tagged”
- Use protective eyewear, especially when drilling or grinding metal
- Wear insulated rubber gloves when working on any circuit or branch circuit
- Always use insulated tools while working with electricity
- De-energize the electrical wires on which you will be working. Tag the circuit breaker to prevent someone from switching it on accidently
- Electrical wiring in wet or damp locations or underground must be within a PVC conduit
- Underground wiring conduits should be at least 18 inches below grade as per code
- All receptacles for equipment that could be in wet or damp locations should be equipped with Ground Fault Circuit Interrupter (GFCI)
- Never use old frayed cables, damaged insulation or broken plugs
- High voltage equipment should be properly grounded to insure electricity flows directly to the ground and not through the person in contact with the live wire
The bottom line is that solar power systems installed on a detached garage (and other parts of the house) can result in enough savings to offset your electricity bills. You will really appreciate its usefulness when the grid breaks down in a storm.
Solar power is earth friendly and will reduce your carbon footprint. The Federal Government will give you Tax Credits too!
The initial setup cost is substantial but you will recoup your investment much before the warranty on the system expires. You can also avail of financing options.
So what are you waiting for?
Thank you very much for reading the post. I do hope you found it informative and useful.
DIY Solar Garage
About: Ordinary guy with no special skills, just trying to change the world one backyard invention at a time. See more at: http://300mpg.org/ On @300MPGBen and at Ecoprojecteer.net About bennelson »
Welcome! In this Instructable, I’d like to show you how I installed my own grid-interactive solar array, so that you can too!
To start with, this is a Grid-Tie or Utility-Interactive solar system. That means that I’m WORKING WITH my electric utility to be a producer of energy with them. (Off-Grid is great too, but it’s not what we are talking about today!)
GRID-TIEIn a grid-interactive system, a home is already connected to the power utility and remains connected to the utility but also has the ability to create and use solar energy. If more power is still needed, it can be brought in from the power utility. If MORE solar is being created than is being used, it gets exported to the utility, and the producer of the energy gets credited for it!
FULLY-PERMITTEDMy dream was to be able to produce all the electricity my home uses, and in the summer when solar production is at a peak, actually EXPORT renewable energy to my neighborhood! This is a FULLY PERMITED system, inspected by my local building inspector and approved and working with my local power company. It has plenty of safety features and a legal agreement with my power company regarding how power is bought and sold from each other.
My house also happens to be on a busy road, with plenty of traffic going past. Even though I’m a Do-It-Yourselfer, I wanted my solar to look GOOD! One of the more common arguements I hear against solar is that people don’t like the look. I wanted to do a good job, as my solar would basically be a billboard for renewable energy due to how many people would drive past it every day!
This solar was also part of a larger project. the complete demolition, expansion, and rebuilding of my garage. My old detached garage was falling down and needed to be replaced. My Dad, brother, and I built a new garage, complete with insulation, heated floor, loft storage space, electric car chargers, and a roof designed to hold solar panels. New construction is an ideal time to plan for solar!
This Instructable will cover the design and installation of the Photovoltaic Solar system.If you would like, you can get started by watching this extensive video I made on the solar aspect of the project.
- 24 Helios brand 260 watt panels (6.24kW)
- Enphase brand M215 micro-inverters
- Iron Ridge brand racking system
- S-5! brand clamps for metal roofing
- Final cost of 6,523.70
- A simple economic ROI of 6.5 years or less
- Fully Licensed and Permitted
- Saves 1,000 per year
To see live and historical power production of my solar, please visit the public information link at: https://enlighten.enphaseenergy.com/pv/public_sys.
Step 1: Planning
The first step is of course TO PLAN!
I usually start almost any project by learning all I can about the subject. That means hitting the library, reading through the web, and taking classes.
I already had some experience in electricity from working on DIY Projects such as building a Solar Powered Kids toy car and a full size street-legal electric car. I had also taken a non-credit electricity class through my local technical college, and a course on Photovoltaics through the Midwest Renewable Energy Association. Although you don’t need to be an electrician to work with solar, you do need a general knowledge of AC and DC electricity and safety.
This particular project will be a net-metered, grid-tie system using micro-inverters.
NET-METERINGNet metering is the process in which you can export power to the grid and get credited for it. The power company bills you only for the difference in how much power you create versus how much power you use. Most the United States has requirements that the power utility MUST allow you to sell power to the grid. Hawaii does NOT allow export back to the grid (although you can have solar and be connected to the grid at the same time, just not export) and several States have other specific local rules. For details please visit here and contact your local power provider. If laws or regulations are ever changed, existing solar installations are typically grandfathered and continue operation under the original contract with the power utility. Before beginning a grid-tie solar project, contact the power utility to find out what requirements they will have. They may specify a maximum size, safety equipment required, or other specifics.
One of the first things you want to know is how much electricity you actually USE.
ELECTRIC USEA great place to start is to look at your utility bills. On an electric bill, there will be a usage listed with the units being in kWh or kilowatt-hours. A kilowatt-hour is a unit of ENERGY, a certain amount of power used for a certain amount of time. If you have a 100 watt light bulb and you leave it on for 10 hours, that’s one kWh of energy. (100 watts x 10 hrs = 1,000 whrs = 1 kWh)
The United States national average home uses about 900 kWhs of electric energy per month. We tend to use less than that, as confirmed by looking at my monthly bill. Some bills also show historical use. That’s nice to know, as you can compare your energy use this month versus the same month last year.Many homes tend to use the most electricity in the summer (do to air conditioning) and solar is a good match, as it produces the most energy in the summer as well.
We are typically using around 600 kWh of energy per month, and ideally I would want a solar array that would produce that much power. At 30 days in a month, that’s 20 kWhs per day that I would like to produce on average.
HOW MUCH SOLAR?How much sun a certain location gets in a day varies quite a bit depending on location and weather. Fortunately, that information is only a click away, thanks to the internet. How much sun a place gets, per day, on average, is called Solar Insolation. Take a look at a map to see how much sun you get where you live! In my area, we get 4 to 4.25 sun-hours per day. If I want to create 20 kWhs per day and divide by 4, I get roughly 5kW. So, I’ll want about a 5,000 watt solar array. But that’s only if everything is PERFECT! In the real world, the solar panels might not face perfectly south, get dirty, or have shading issues. So, I’d really like at LEAST a 5,000 watt system.
RESOURCESHere are some resources which I found extemely helpful when researching and designing my system.
- Non-Profit Renewable Energy groups, such as the Midwest Renewable Energy Association. Training, classes, and great educational resources.
- Technical or Community Colleges. Non-credit classes can be very useful at low cost!
- PV Watts. Online solar calculator to help you predict how much power you can create.
- HOME POWER magazine. Print and online renewable energy magazine for professionals and DIY alike.
- Renvu.com System Designer. Mail order supplier of solar components has a fantastic tool to help you design a system and create a parts list and total cost estimate
- Iron Ridge Design Assistant. Racking manufacturer has a great software tool to help you calculate not just which parts you would need, but also calculates wind loads and snow loads.
- Solar Design Tool. Software for permiting including single line diagrams. They have a free trial. I used the free trial to design my system, and didn’t pay anything at all.
- YouTube. YouTube can be a great source of information, but sometimes the hard part is finding the right source! I found that Webinar style videos from equipment manufacturers were very good. Videos by do-it-yourselfers could be inspiring, but often didn’t show best practices or details of the systems. There’s also some great videos by equipment dealers. The altE store sells solar components, but also does a great job helping EDUCATE the public about solar.
- Renvu.com. Best overall internet mail-order for solar components. They also have that great design tool that helps you create your own system and export a parts list and budget from it. I bought many of my components from them.
- Werner Electric. This is a local electric distributor in my area. These are the types of companies where electricians buy their supplies and materials. They sometimes have a small retail store or walk in parts counter. I bought all my racking through them and was able to get shipping from one location to another for free. Although the local branch didn’t carry any solar components, they always have trucks going from one location to another. The racking is 14 feet long, and normally would have a special freight fee if shipped by Fedex or UPS. By ordering it through a local branch of an electrical supplier, I could just pick it up at will call and save all shipping costs. They also had a salesperson there who specialized in renewable energy, who I could ask a few questions of. Look to see which electrical supplier is in your area who can get you solar related components
- e-Bay. If you know exactly what you are looking for, e-Bay sometimes has great deals. I purchased 24 brand-new micro-inverters from an e-Bay seller. They were brand-new, exactly the number I was looking for, and exactly the number the seller was clearing out. I got a good price and a great transaction. Always to your due diligiance and check the seller’s rating and reviews to make sure they are trustworthy and that you get exactly what you are looking for.
- Local Hardware or Home Improvement Store. For basic electric items, nuts and bolts, and all the other items you are forgetting, it’s nice just to run to the local store to get them. It’s also nice to NOT pay shipping and be able to return any items not used.
- Local Solar Companies. You might have some solar companies right near you which may be an excellent resource! I ended up buying my solar panels from a local solar company, and just picked them up on a trailer to save on shipping charges. Shipping solar panels from out of state may have cost me up to 600.
After taking a look at my own electric use, learning all I could about solar, and even finding some good resources and places to buy the solar equipment, I still needed to know exactly how well my site would work with solar.
So, let’s do a Solar Site Assessment.
Step 2: Site Assessment
You need to know if your location is appropriate for solar or not.Not all locations are.
A site assessment is really just a good look at your location of where you are planning to put the solar and seeing if it is a good match or not. Concerns are typically shading, lot lines and set backs, roof condition (if solar will be mounted on a roof,) locations of underground and overhead utilities, and location and distance to connection to the grid.
PUT SOLAR PANELS IN THE SUNSolar doesn’t work everywhere. You can’t put a solar panel under a rock and expect it to produce power. Neither can you place it in the shade. Ideally, solar needs a clear, unobstructed view of the sun for as many hours of the day as possible. In the northern hemisphere, that means solar panels should face south. They should also be on an angle to match the height of the sun in the sky as much as possible. Make sure you mount your solar panels someplace sunny! My yard is pretty shady, and the only really sunny spot is my garage. My plan was to mount the solar on the south face of the garage roof. In designing the garage, we made sure that anything that broke up the roof (sky lights, chimney, vents, etc.) was on the north side, leaving the south side to be a large blank slate for the solar.
SOLAR PANEL ANGLESolar panels are commonly tilted to the same angle (or at least with 15 degrees of that) as the latitude of your location. For example, I’m in south-eastern Wisconsin in the United States at about 43 degrees north latitude. Having my solar panels mounted at 45 degrees would be pretty much ideal. In the summer, the sun may be higher than that, but in the winter, it would be lower. On average, I’d be producing an ideal amount of power.(In a location closer to Equator, a flatter or lower pitch arrangement is great. The further north you go, the steeper you want to mount your panels.)
In my case, I built the garage with the plan to install the solar directly on the roof. We designed it with a sturdy structure to support the weight of the panels, and had it roofed with metal (instead of asphalt shingles) for long-lasting durability. If you plan to install solar on your roof, make sure the roof decking and shingles are in good condition. If neccessary, re-roof or complete other repairs BEFORE installing solar. I was surprised to learn that a metal roof with solar weighs LESS than a plain roof with just asphalt shingles! If you have concerns about the load-bearing ability of your existing building, consult a professional roofer or engineer.
My roof is a little less than 7:12 pitch. That’s not as steep as I would like it to be for ideal solar access, but I was limited by local building codes. (A steeper pitch would have meant my height would be taller than a legal 18′ limit for a garage.) Although not a perfect angle to the sun, it’s still a GOOD angle, and the garage otherwise faces due south.
For a grid-tie system like mine, we want the angle to give good average year-round production. In off-grid setups for charging batteries, solar panels should be angled for maximum gain in the month of the year that uses the most energy compared to what the panels can produce. That’s typically (but not always) a winter month like December or January.
SHADEMy property is somewhat narrow and runs north-south. My next-door neighbors have a row of nice large maple trees right on the property line. Clearly, these would shade the solar panels at some point during the day at least part of the year. I also have a pine tree in the front yard. Late in the year (near the winter solstice) the shadow of that tree might reach all the way to the garage.
But how would I know if these shadows would effect my solar system or how far they would reach?
A great tool for this is something called a Solar Pathfiner. I borrowed one from a friend, and used it to check how shading would effect my system. The device itself is a reflective dome with a compass and tripod legs. A person inserts a piece of black paper inside which is printed with the angles of the sun through the year based on their latitude. By looking at the reflection of trees, buildings, and other obstructions in the reflection in the plastic dome, a person can trace those out on the paper and see how much of the sun will be blocked at any time during the year. The paper is also printed with numbers representing what percent of solar energy is created during that hour of the day. By counting the sections blocked by obstructions, a person can figure out what percent of solar power is blocked for each month of the year.
In my case, I definately had some shading, and it was the worst in the winter months. The upside of that is the winter months are when there’s the least sun, and thus the least solar power production anyways!
Overall, I still had a very good view to the south from 9 AM until 3 PM every day. That’s the solar window when most of the power production is going to be created. Power production is less outside
Besides using a tool like a Solar Pathfinder, you can also simply observe your property at different times during the year. When building the new garage, the roof was in place before this last year’s winter solstice. I set up a small camera on a ladder to create a time lapse. That way, I could see how the roof was shaded and when.
MICRO-INVERTERS HELP MAXIMIZE POWER IN PARTIAL SHADE SITUATIONS
Because I knew that I would have some shading issues, I chose to use micro-inverters for my system. An inverter is a device that takes Direct Current (DC) from the solar panels and converts it to Alternating Current (AC) as is typical in most homes from the power utility. In traditional inverter systems, solar panels are connected in series (one to the next to the next to the next) to get to higher voltage and is then converted to AC at the inverter. One limitation of that system is if one solar panel is shaded, it becomes the weak link in the chain, and reduces the current from ALL the panels in series, limiting total power created.Alternatively, a micro-inverter is a small unit mounted right at the solar panel. It converts the power of one panel to AC, and then that AC power is combined (in parallel) to feed the home. If one panel is shaded it does not effect the power production of any of the other panels.
Besides considering shading, you will also want to measure and sketch the area you plan to install solar. If it’s on a roof, confirm the construction and quality of the roof, and make sure the roofing material is in good condition. Also measure the distance from the solar array location to the point it will connect to the grid (often the main Utility Meter.)You will also want to inspect your main electrical breaker panel, see how many spare spaces are available and the capacity of the panel and bus bar capacity if known. You will need to know this information for designing the solar system and filling out paperwork required by the utility and building inspector.
Step 3: Proposal and Permitting
I live in an area where building permits are required from local authorities before home construction or remodeling. I also needed my utility’s permission to connect with solar. The utility would properly credit me for any energy I created and exported to the grid. The system also needed to be shown that it was safe and within other parameters required from the power utility.
Because of this, I needed to create a proposal for my power company and get an electric permit from my town.
To plan my system, properly design it, including using the right size wire, etc., and create paper-work to present to the AHJ and Utility, I used the following software tools:
- PV Watts online solar calculator
- Renvu Instant Design and Quote
- Iron Ridge Design Assistant
- Solar Design Tool
These are all free online tools available to anyone.
I used the Solar Pathfinder to know how much loss I could expect from shade, and I used PVWatts to calculate how much power I could expect to produce in my location during any given month, and in total over a year.Here’s a video showing how to use the PV Watts solar calculator from the National Renewable Energy Lab.(Please view the software demonstrations FULL SCREEN and in HD to view all computer monitor text.)
(After six months of solar electric production, I checked the estimates from PV Watts versus my real world energy production. As long as I including the shading information from the Solar Pathfinder, the predicted energy production was almost dead-on!)
Since I knew how much power I used (from my electric bills,) and how much power I COULD expect to create (as calculated with PV Watts,) I could start deciding what components I might want to use.
I found that one of the places with the best mail order was Renvu.com. That web page also has a great software tool to help DIY’ers design their own system.I used Renvu’s design tool to help me decide that I wanted a system with 24 solar panels (maximizing how many fit on the roof) using micro-inverters (to help with the shade.)
Here’s a video showing how to use the DIY Kit Designer on Renvu.com
I also wanted to double-check the materials I would need to mount the solar panels. The Iron Ridge Design Assistant is a free tool which helps you design the racking system to mount the solar. This includes information on snow loads and wind loads, ensuring that your solar panels neither collapse a building nor get blown off the roof! Your building inspector will appreciate seeing those numbers and know that some engineering thought was put into your system.
The last really great online tool I found to help me plan my system was at SolarDesignTool.com. This is full-blown solar design software for professionals. The best part is that there’s a FREE 30 day trial. I used the free trial to design my system and export a professional report in PDF format to give the the Building Inspector and Power Utility.Here’s a walk through of the SolarDesignTool software:
Since I now had my plan, I could get the ball rolling with the Power Company.
INTERCONNECTION AGREEMENTThe Utility would end up having me fill out two forms: PSC 6027 and PSC 6029. These are both part of the Distributed Generation Interconnection Agreement. The first form being an application, and the second being the completed agreement itself. I would have to specify to the utility what equipment I would use, the total power of it, and other details, including proving that I have appropriate levels of property insurance. I filled out and submitted the PSC 6027 form and also attached an application packet which included a map of my property, proposed location of the equipment, a single-line diagram of how the equipment would be wired, and PDF spec sheets of every piece of equipment I would use. I was told that an electric utility engineer would review the proposal and get back to me. Most of what I gave to them (particularly the single-line diagram) was generated in the SolarDesignTool software. I manually created my own map of my property, using a screen grab from Google Maps, to show the proposed location of the solar panels, AC disconnect, and other key pieces of equipment.
The total paperwork that I submitted to the Utility was:
- Cover Letter
- Site Plan (map showing property, property lines, solar equipment, etc.)
- PSC 6027 (Interconnection Agreement Application)
- Solar Array Diagram
- System Summary
- Electrical Single Line Diagram
- Individual PDF spec sheets of all equipment to be used
- Equipment Grounding Technical Brief
The Distributed Generation Interconnection Agreement is actually a CONTRACT. It specifies the relationship between the Power Utility and the Distributed Generator (which is now me.) While it’s always possible that rules or regulations of grid-tie solar power change in the future, this contract guarantees your particular arrangement.
ELECTRIC PERMITI also needed to get an electric permit. In the solar world, there’s something called the AHJ. that’s the Authority Having Jurisdiction, and it varies from one area to another, but commonly, it’s the local building inspector. Ahead of time, I sent the building inspector the same packet of information that I sent to the utility. I had already worked with the building inspector for the general construction of the garage, so he knew who I was, what I was doing, and that the solar was part of the plan from the start. I met with the building inspector and asked if he had any questions/Комментарии и мнения владельцев/changes on what I was planning to do. He did not, he simply asked that I get an separate electric permit specifically for the solar, which cost me 100. On the electric permit, the licsensed electrician doing the work must be listed, along with his/her liscense number. It’s usually the contractor who pulls permits, not the home owner. I had already contacted the electrician who did wiring in my garage, got his liscense number, and arranged for him to come out sometime in the future when I was ready to wire the solar.
ANY QUESTIONS?After about two weeks, I heard back from the power utility. They approved my proposal with no changes, questions, or Комментарии и мнения владельцев. Putting in the time on the paper-work was well worth it. It felt great to know that I had planned everything out correctly from the start.
I know that this entire step has felt like a LOT of WORK and a lot of PAPERWORK. Keep in mind that MOST of this information needs to be known in the first place to properly design and install a solar system. Actually providing that information to the power company isn’t all that difficult. Likewise, whatever you have for construction requirements in your area, you want to make sure your system is safe and properly installed, whether or not a building inspector will be looking at it.
NET-METERING/DUAL-METERINGThe utility would later come out to reprogram my Utility Meter. In my area, we have Smart meters which communicate directly back to the utility. They are digital and designed to read only for power PULLED from the grid. The utility made a software change to my meter so that it could read and track separately the power pulled from the grid AND power created from my solar and back-fed to the utility.
LOAD-SIDE CONNECTIONI would also be allowed to make a load-side connection. A load-side connection is the simplest and most cost effective way to connect solar power in to a house. An additional circuit-breaker is added to a panel and AC power is fed IN through that breaker. There are some limitations to this. For example, the total input breakers can’t add up to more than 120% of the bus bar capacity. (Read this to learn more.) The input breaker also needs to be placed at the far opposite end from the main breaker of the panel. I double-checked and confirmed that my power and bus bar capacity was appropriate.
It’s VERY important to work with your AHJ and Utility to understand how they require connections to be made. Also, make sure you understand the agreement with the power utility in terms of how electricity is billed and credited.Some utilities may require that a second meter is added. The original meter will show energy you use, and the new second meter will show power exported to the grid. Adding a second meter should be performed by a professional electrician.
During a web search, I found a PDF file from another utility company which gives VERY specific instructions in how they want distributed generators to connect to their system. (Please see the attached Alliant DG Specs.pdf file.)
HOW DO I GET PAID FOR MY SOLAR?Power utilities vary in how they pay for electricity that the homeowner exports to the grid. In many cases, the home-owner buys at retail, but is only credited or paid for the avoided cost of energy exported. Avoided cost is the cost at which the utility would have had to purchase the electricity from somewhere else. In essence, it’s the wholesale cost. In my area, that’s 3 or 4 cents per kWh.Some utilites may also have an annual tally-up. Credits from overproduction of electricity may only be carried over for up to a year, and then a check is written out for the credits, or in some cases, they are just cancelled out. Sometimes the month at which you begin to produce solar power can can be important. For example, you wouldn’t to produce excess energy all summer, hit your annual cut-off, and then have to pay for electricity all winter.I’m fortunate in that my local public utility credits me the full value of any electricity I export. In the summer, I can create and build up a credit. In the winter, I will use more electricity than I produce, and will draw down that credit. I have no electric bill in the summer, and may only have a relatively small electric bill in the winter
Step 4: Racking
So how do the solar panels get attached to the roof? They don’t. The panels are actually mounted to a racking system which attaches to the roof.
All components used in a racking system should be either aluminum or stainless steel. materials that can hold up to a life-time of the elements. A few non non-structural components can be plastic, such as rail end-caps. If plastic zip ties are used, they should be of the UV resistant type and under the solar panels where they are protected from the sun.
I chose the Iron Ridge brand of racking components. I had seem samples of their materials and spoken with a representative while visiting the MREA’s Energy Fair. Their system looked good, and it was carried by my local electrical supplier. The Iron Ridge components were also certified to work with the integrated ground system in the Enphase micro-inverters. By electrically bonding the racking, frames of the solar panels, and the micro-inverters themselves, the entire system is properly grounded WITHOUT requiring a separate heavy copper cable. (This was one thing I wasn’t sure if the utility or building inspection would allow or not, but neither took any issue with it. Grounding this way saved material cost and labor.)
I chose the Iron Ridge XR-100 racking. This is their flagship material. It’s a sturdy aluminum extrusion with slots to accept bolt heads. It’s available in stock several lengths. I chose the 14 foot length. My garage is 29 feet wide, but the solar panels wouldn’t be going all the way to the edge. Two pieces of 14′ racking with a splice between them creates a 28′ long piece. I would have three rows of solar panels. Each row requires an upper and a lower piece of racking, so I would need 12 pieces total. I ordered them in through my local electrical distributor and picked them up with my car and trailer to save freight charges. I now drive an electric car, and it felt pretty good to use that vehicle to pick up the materials that would eventually power that car straight from the sun!
I have a metal roof on the garage, so I would use special attachments to connect the racking to the roof itself. I chose S-5! brand clamps. There are quite a number of different styles of metal roofs, and the clamp must match the roofing style. Mine is a Nailing Strip metal roof, the profile of which looks something like a capital letter A. The N type S-5! mini clamp was the one I would need for my roof.
Typically, a person needs to calculate home many points of connection there are between the racking and the roof itself. That is based on wind and snow load of an area, the sturdiness of the racking system, and the structure of the roof. Fewer points of attachement saves time and money, as well as fewer HOLES in a roof! points of attachment means more cost of materials and time spent to install them. One thing I loved about the S-5! clamps is that they are NON-penetrating. They do NOT put holes in a roof, rather, they pinch onto the standing seam of the metal roof.
The roofing material has a seam every 16 inches, and the clamps can ONLY go on the seams. So, my choices for spacing the clamps was easy. 16, 32, 48, 64, or 80 inches. 16 inches would be every seam. complete overkill. 80 inches is 6’8, that was just a little longer than the maximum span listed for the product based on my wind and snow loads. I sketched out several layouts and found that going to every 48 inches made things nice and easy for me in terms of how the seams of the roof layed out. It was easier to center the panels and space them out, while only using a few more clamps. I could then make a sketch of which seams of the roof would have a clamp.
Using the Iron Ridge Design Assistant, I now knew how big my solar array would be, and I essentially centered it on the roof. I used a tape measure and pencil to measure from the bottom edge of the roof up, and made a mark. I did that on both ends of the roof. Next, I installed an S-5! clamp on the two ends of the roof. Then, I stretched a string taught between the two. That gave me a nice straight line so that I could arrange all the clamps in a row. (I could have also snapped a chalk like, but my yellow string was nice and bright. Blue chalk on a green/blue metal roof would never show up!)
For each clamp, I loosened the set screw all the way, placed the clamp against the seam, pushed against it, and gave it a smack with a rubber mallet. This would snap the clamp into position. I then tightened the the set screw. The first few, I used a torque wrench to make sure those screws were to the correct tightness. Once I had done a few, I had a sense of it and simply drove the screws.
With the clamps in place, I then added the L-foots, and bolted them in place with the included hardware. The L-foot is exactly what it sounds like, an L shaped piece that connects the S-5! clamp to the racking.
Next, I was finally ready to attach the racking itself. I simply set the racking over the bracket, put a bolt from the racking to the L-foot, and tightened down the nut. I actually ended up using two different types of bolts. There is a square-head bolt, which slides into the racking from the end, and can’t fall out, and there’s a T-head bolt, which can slip right into the groove on the racking, but can also accidentally fall out before it’s properly tightened. The T-head bolt was easier to use, as I didn’t have to plan ahead sliding the right number of bolts into the end of the racking before installing it.
I also needed to create a splice to connect one piece of racking to the next. This was very simple. I just slid the splice component in, drove in two self-tapping screws, slid the other piece of racking on, and drove in two more screws. Easy-peasy.
The metal roof was steep and slippery. I literally could NOT stand on it without sliding down. However, once I had the first piece of racking in place, that gave me a place to stand and prevent me from sliding off the roof. From there, I could install the next row of racking. I did this one row at a time. When the row was finished, I moved up onto it and worked on the next row up. In this way, I got to play a real-world Donkey Kong game, building my way up the roof. I spend most of that time sitting on my butt. I also always had a cardboard box with me. That gave me a place to hold the S-5! clamps and my tools, and it stayed nicely against the racking. I was also rock-climbing harness, which I hooked to one of the fully mounted rails as fall-protection. I later purchased a full fall harness and auto-retractor.
Once the racking is otherwise installed, I also added plastic end caps to the rails. Those are mostly cosmetic and give a finished look.
Note: The S-5! metal roofing clamps are difficult to remove and reposition. Always confirm their location before installing.
Step 5: Micro-inverters
Advantages of Micro-Inverters:
- DC to AC right at the panel
- NO HIGH VOLTAGE DC POWER
- Rapid Shut-Down. In case of a power failure, ALL current is cut all the way back up to the solar panel. A great safety feature and a future requirement for all solar arrays.
- Wiring Simplicity. All required wiring is just 240V AC wiring. stock and trade of any electrician
- Distributed. If one micro-inverter fails, all the rest still function
- Shade-Tolerant. Each panel is independent of the rest. One shaded panel does not reduce production of other panels
- Plug-and-Play, just plug into trunk cable
- MPPT. Each inverter automatically maximizes power output, regardless of voltage
- Easy Expansion. additional inverters can be added in the future with no other special equipment
- Panel-Level Data. Micro-inverter systems can tell you how much EACH INDIVIDUAL panel is producing. Great for data-nerds and for trouble-shooting
- Integrated Grounding (specific to this brand/system) No additional heavy copper cable/lugs/ground-rods.
DIS-Advantages of Micro-Inverters:
- Cost (typically cost more than a plain series string inverter)
- Cost of Accessories. The trunk cable and required communications gateway are not inexpensive. Communication gateway is required no matter how few or many micro-inverters are in the system
- Hard to Access. Micro-Inverters are on the roof. If one needs to be replaced, one must climb the roof and remove a solar panel. Series inverters are usually mounted at working height on a wall, easily accessible.
- NO SOLAR POWER WHEN THE GRID IS DOWN. This is a safety feature, but it also means that the solar panels create ZERO power during a blackout. If you specifically want solar to charge batteries when power is otherwise NOT available, you do NOT want to use micro-inverters.
Because I have a reliable power company (power outages are extremely infrequent) and I have some shading issues, I dedided to go with micro-inverters. I also like how I only needed to deal with AC power (not high-voltage DC) which meant that any electrician could help me with the project, without any solar experience at all.
The micro-inverters use a proprietary trunk cable. This is special AC wiring with quick-connects for the micro-inverters every 40 inches. Those quick connects are commonly called drops and the cable is ordered based on how many drops you want. I ordered 24. I cut the cable into three sections, each with 8 drops on it, and attached the cable to the rail with plastic clips and zip ties. (This will all be under the solar panels, so sunlight degrading the plastic is less of an issue.)
Each micro-inverter is plugged in to the quick connection on the cable. Those connections have a gasket and are weather-tight.
The trunk cable has two ends. The west end will go into junction boxes to connect the wiring together. The east end is simply cut and hanging there. Each of those three cut ends gets an insulated termination on it. It’s important to make sure that’s a good weather-proof connection. If the system isn’t working, that’s a common point to check and troubleshoot.
The overall process of installing the micro-inverters is very simple. I just laid out the trunk cable, zip tied it to the racking, and bolted the micro-inverters near their connections and plugged them in.
The micro-inverters also have removable stickers on them with their serial numbers. I peeled those stickers off as I installed the inverters and placed them on an included sheet of paper which showed the locations of the inverters. This would later be used for mapping, showing individual inverter stats, and troubleshooting if necessary.
Step 6: Solar Panels
The solar panels for this project are Helios brand 6T series 60 cell 260 watt solar panels. Each one produces about 30 volts. These are mono-crystalline panels with a silver aluminum frame. Each one weighs about 50 pounds and is 6.5 feet long by 39 wide. That’s small enough for one person to carry on his shoulder or two people easily set in place on a roof.
Every solar panel manufactured has a spec sheet available. (Please see the attached 6t-255.pdf) Those sheets will always list all of the details of the panel including its electrical and physical characteristics. Using that information, a person can plan out their system. For example, by knowing how wide each panel was, I could know the width of the racking material I would need to mount them.
The cost of solar panels can vary quite a bit. Always make sure to consider shipping costs as well. In some cases, a loading dock might be required as a pallet of panels might come in a very large truck without some other way of unloading.
Ideally, I wanted to buy American made panels, save on shipping, and get a good deal.
There was a company called Helios, which was a U.S. manufacturer located only about 30 miles from my house. Unfortunately, they are now out of business. I located a small rural solar company which had a stock of new Helios panels available for sale. We drove to that business, bought the panels, loaded them on a trailer, and brought them home. I paid 150 per panel. For general solar panel purchasing, I’d recommend that you take a look at what’s in stock and on sale at Renvu.com.
A few years earlier, I had gone to Helios to buy a single large solar panel which I used on my daughter’s playhouse. While there, I got a few shots of inside the factory. It was neat to be able to purchase locally made solar panels and actually see the panels I use being made.
Here’s my brother and I taking the trip to go get the solar panels for the garage.
Step 7: Wiring and Conduit
Before wiring, a person needs to know where the wires are going and what type and gauge to use!
Circuit calculationsOne of the first steps is doing circuit calculations. Because I was using Enphase micro-inverters, I first consulted their materials. (Please see attached PDF files.) The trunk cable uses 12 awg wiring, which can only handle a certain amount of current. The Enphase PDF lists that up to 17 micro-inverters can be used on a single circuit. Since I have 24 micro-inverters, I would need two circuits. Due to the physical layout of the panels (3 rows of 8 panels each) it seemed to me that the best way to divide up the panels was for one row of panels to be a single circuit and the other two rows to be the second circuit. I would simply have one section of trunk cable on each of the three rows, going to the west side of the roof, and meet in a junction box. The Enphase materials specify how to do a calculation to make sure you are using appropriate wiring, and that thicker wiring is required if the wire run is long, has too much current going through it, etc. I did those calculations and confirmed that I could use 12 awg wiring.
JUNCTION BOXES:One thing I had a bit of difficulty in finding information on was Junction Boxes and how to make and install them. I couldn’t find much good information in online videos, and they aren’t main components, like solar panels, where the manufacturers provide installation materials. I eventually found that most solar installers are using basic off-the-shelf outdoor rated plastic electrical boxes. I would need three boxes, one for the end of each of the three rows. For the top box, I used a two-gang outdoor box. For the other two, I used a 6x6x4 outdoor box.
I drilled holes in the boxes for 3/4 conduit and for the trunk cable to enter the box. That cable went through a weather-proof cable-gland which tightens down around the cable. I drilled through the plastic boxes into the aluminum racking with self-tapping stainless steel screws. I mounted the boxes so that they would not stick up above the racking to interfere with the solar panels. There’s enough room at the bottom of the boxes for the conduit to travel UNDER the racking to run down the roof. All the boxes, wiring, and conduit are up off the roof.The junction boxes and conduit will all be UNDER the solar panels, where they will be protected from the heat and UV damage of the sun.
CONDUIT:I made use of PVC conduit as it is easy to cut and glue. perfect for a do-it-yourselfer. I had no experience bending metallic conduit. The 3/4 conduit travels down to the lowest piece of racking where it makes a 90 degree turn to the west edge of the roof. At this point, I supported the conduit by binding it to the racking with large stainless steel hose clamps. Unlike plastic zip ties, stainless steel won’t degrade at all with exposure to sunlight.
AROUND THE EDGE:I wasn’t sure exactly of the best way to make the conduit go around the edge of the roof and make the transition of going down the wall. I purchased a large bag of assorted PVC elbows, 45 degree angles, and LB pulling bodies so that I could experiment with going around that edge. In the end, I decided that two LBs allowed me to get the conduit as close to the building as possible, which looked the best. This was also part of the solar system easily viewable from the house. I made sure to get my wife’s opinion on how the conduit looked before permanently gluing and mounting it. Once she liked it, I completed the work.
COMBINER/DISCONNECT BOX:Most Power Utilities, including mine, require an external AC Disconnect. This allows utility workers and emergency personnel (Firefighters!) to disconnect the solar array if the need arises. Because I had two circuits, I also needed to COMBINE the two circuits into a single larger one. I chose a box which would both combine the circuits AND allows for AC disconnection. This box was the Midnite Solar AC Disco. It has space inside it for up to three 240VAC circuit breakers, and is lockable in the OFF position. I purchased the enclosure with two 20A circuit breakers. I put the box on the wall, marked the location, and then drilled a hole through the wall. I pushed a short section of conduit through the wall. This connects into the BACK of the disconnect to pass the power from outside the building to inside.I installed the two 20A breakers and finished running the conduit down the roof and to the disconnect box.I really like this combiner/disconnect. I think it looks nice and it does it’s job properly. Some utilities or building inspectors may require that you use a dedicated AC disconnect and a dedicated Combiner. Make sure you know exactly what they want before beginning the project.
ELECTRICIAN AND WIRE PULL:I hired the same electrician as did the general wiring in the garage. I did as much of the electrical work myself as I could, before he came over to save time and cost. I already had the junction boxes in place on the racking and the conduit running down from them. The electrician supplied the wiring, and had several different colors on spools. He put them on a roller stand to unroll. I got on the roof and the electrician stayed on the ground. We pulled wiring from the spools, up to the first junction box. I ran a fish tape from the top box to the middle box, and then used that to pull the wiring to the top box.
Inside the top box, I made the connection from the four wires of the trunk cable to the four wires we just pulled up through the conduit. This was simply stripping the wires, twisting the matching colors together, and completing the termination with a wire nut. At the middle box, I repeated the same process, this time with the other bundle of wires. The two groups of wires were bundled together with electrical tape to make sure I could keep track of which was which. We also used a different color wire (purple instead of red) for one of the hots to differentiate the two groups of wires. (Yes, purple wires are to code! Red and black are the most common, but other colors can be used, although not white or green!)At the bottom box, I cut the wires of the second bundle, stripped them, and then combined both ends of the cut wires with the bottom row of solar trunk cable. This electrically combined the middle and bottom rows together into one circuit.
While I was working on the roof, the electrician finished installing the combiner/disconnect box and fed 10 awg wiring from it to the breaker panel. That wiring goes through a 30A breaker into the panel at the end opposite of the main fuse.When I was finished making connections on the roof, we pushed the end of the wiring down through the conduit to the disconnect box and made the connections at the two 20A breakers.My total fee for the electrician and materials (mostly the wire) was 431.92. I had done very little household wiring before and NO serious solar wiring. It was nice to have a professional there to look over my work and confirm that I was doing everything correctly. I was also required to have a licensed electrician to do the final hook up and get the electrical permit in the first place.
FIRST SOLAR PROJECT:When I asked the electrician how many solar projects he’s worked on before, he said None, this is my first, but it’s just 240VAC wiring, that’s what I do all day.One of the reasons why I wanted to use micro-inverters is because all of the wiring is the same type generally used in households. Electricians and building inspectors are already used to it, whereas they might NOT feel knowledgeable or confident with high voltage DC.
How Much Roof Space Is Needed For Home Solar Panels?
When it comes to residential solar panels, your home’s roof is the most obvious place to put them. But it’s easy to get confused about how much roof space is needed for solar panels in order to install a home solar power system. Not all roofs are constructed to the same size or specifications, and some homes have roofs with steeper pitches, while others have roofs with more faces or odd shapes.
We’d love to tell you a simple formula for the exact amount of square footage that is required for a certain number of panels, but it’s not quite that simple. Each residential solar panel array is custom designed to match the homeowner’s needs and the unique size, shape, and dimensions of their roof, so the square footage that’s needed is going to depend on a number of factors.
If you’re wondering, “How many solar panels will fit on my roof?” then here are a few things to consider.
How To Calculate The Solar Potential Of Your Roof
There are a few rules of thumb you can follow that can offer a general idea of how much roof space is needed for solar panel installation. These guidelines can also help determine how much roof space you have available to put solar panels on.
Generally, every square foot of roof space has the potential to generate about 15 watts of solar energy. Thus, a solar panel installation on a small home might only need around 200 square feet of roof space, while a larger home can require more than 1,000 square feet of roof space to properly offset electricity usage.
To offset an average amount of energy usage by the average American home, you’ll typically need around 18 to 24 panels to be effective. That is, of course, if everything about those panels is ideal, where the positioning is optimal, the panels are of a standard rating, and the location gets adequate sunlight year-round. If you change any of those variables, the number of panels you need is going to change as well.
If you want to get a sense of how many panels a roof can support, you don’t need a fancy solar panel square footage calculator. Here’s an easy calculation you can do: Multiply the square footage of your roof by.75 to account for the required solar setback. ( on that below.) Take that number, and divide it by 17.5, which is the average square footage of the standard solar panel size. The resulting number is the maximum number of solar panels you can fit on your home’s roof.
If you’re not sure of the square footage of your roof, there’s another relatively easy calculation you can do: First you need to know the dimensions of your roof from ground level. You can measure two sides of your roof from the ground, and then multiply those numbers together to get the square footage. If your roof isn’t flat, you need to account for the angle of your roof as well, so measure the angle from the ground (most smartphones have angle measurement apps that you can use) or just use 35 degrees to get a rough estimate if you don’t have an unusually steep or shallow roof. Then take the square footage that you measured from the ground and divide it by the cosine of your roof’s angle to get the total square footage. If you need a solar panel square footage calculator, you can click this link to get a sample calculation for a roof that measures 400 square feet from the ground, and has a 35 degree angle, and then just change those values to match the measurements that you take.
How Close Can Solar Panels Be To The Edge Of The Roof?
Most roof-mounted solar installations will need a “solar panel setback” for safety. This is one of the most common roof requirements for solar panels in local and state building codes. This setback is the open space between the edge of the solar array and the edge of the roof, and it provides an unobstructed pathway around your rooftop for emergency responders like firefighters to get better access to your home in case of an emergency.
The minimum solar panel setback varies from state to state, but generally, the setback will take up about 25 percent of your roof’s usable space. This accounts for two roughly 36-inch wide pathways that run along the edge of your roof, on a roof with just two basic faces. If your roof is more complicated than that, with multiple faces, or different shapes that come together at odd angles, your setback requirements may be different, which is why it’s important to work with solar professionals when designing your home solar power system. Palmetto’s team of solar designers not only make sure your roof space is optimized for power production but that it also meets the requirements of all jurisdictions as well.
Factors to Consider When Determining How Many Solar Panels You Need
When determining how many solar panels you need, it’s important to start by thinking about what your goals are and why you want to go solar in the first place. Do you want to maximize your return on investment? Do you want to save as much money as possible? Do you want to reduce your upfront costs? Do you want to have the biggest environmental impact and reduce your carbon footprint as much as possible? Most people want a balance of these goals, and may have other priorities as well, so it’s helpful to get a clear idea of what your specific end goals are before you start designing a solar power system.
Once you have your goals in mind, then you can determine how many solar panels you need to get there. This calculation is going to depend on how much energy your family uses, how much roof area you have available for solar panels, the location of your home and the angle of your roof, how much sunlight shines in your part of the country, the efficiency of the solar panels you’re using, and if your local utility offers net metering. Plus, you also need to consider your budget, because a large solar power system might produce more energy, but it’s going to cost more for the initial installation as well.
Here are a few things you should think about when determining how many solar panels you need for your roof.
How many solar panels you’ll need, and thus how much roof area for solar panels you’ll need, starts with an estimate of how much power you use in a given year. There are plenty of ways to determine your annual energy usage, but the easiest is to simply take a look at your current monthly energy bill. It should tell you how many kilowatt-hours of energy you use in a given month, then just multiply that number by 12 to get an annual estimate. If you don’t know your own estimated energy usage, a good starting number is that the average American home uses about 11,000 kWh of energy every year.
You should also consider any potential changes to your family’s energy usage in the future that you might want to account for. For example, if you buy a new electric vehicle that you plan to charge at home, or if you start working from home more often, or if you expand your family with a new child, your energy needs might change pretty significantly from the previous year.
Location (How Much Sunlight You Get)
Different parts of the country get different amounts of sunlight. For instance, Arizona is famous for intensely sunny days. On average, Arizona gets 300 days of sunshine every year. Conversely, Juneau, Alaska, spends more than two-thirds of the year in darkness.
This impacts how much roof space is needed for solar panels, because depending on where you live, you’ll need more or fewer solar panels. So if you live somewhere with lots of sun, you might only need enough roof space for a few solar panels. But if you live in Juneau, you’ll need lots of solar panels on your roof to harness the available energy.
The direction of your roof also determines how many solar panels you need, as southern-facing roofs in the northern hemisphere are ideal, as they receive more direct sunlight and can use that sunlight to create more energy. If your roof does not face south, you may either need a more complicated installation to get your panels facing the right direction, or you may need more panels to make up for the difference in energy-creating potential.
Size and Rating of Your Solar Panels
Solar panels can vary in size and rating, leading to different sized systems for the same amount of energy output. Some panels might be smaller but have a higher watt rating, which means they’re more efficient than a larger panel with a lower rating. That’s why you must consider the efficiency of the panels when determining the total solar panel system size for your roof.
While the efficiency of solar panels might vary, solar panel sizes typically don’t, as most companies have a standard solar panel square footage to make installation easier. The standard solar panel size dimensions are about 65 inches by 39 inches, which is roughly 17.5 square feet.
Your Solar Budget
Generally, larger systems are a great way to quickly offset your current electrical and fossil fuel energy usage. However, larger systems are naturally more expensive. While you may have the roof real estate for a large array, you might not have the financial budget for it, and vice versa.
Another thing to consider when figuring out your budget is whether your local utility offers net metering, and what rate they offer for that net metering. If you’re not familiar, net metering is when your utility company offers you credits for the extra energy that your system produces and feeds back into the grid. These credits can then be used to offset the cost of power that you might need to draw back from the grid, such as at night or during storms if you don’t have a battery storage system. If your local utility offers a generous net metering policy, it may allow you to expand your initial budget and then make up that difference over time.
Is It Possible To Install Too Many Solar Panels?
Believe it or not, it’s not always beneficial to install as many solar panels as you can possibly fit on your roof. Adding extra panels that aren’t needed just increases the cost of your initial investment, and if you don’t have a way of capturing or getting credit for the extra energy that you’re generating but not using, then you’re not getting a good return on that investment.
A good solar installation should offset as close to the exact amount of energy that you use as possible. That’s why we typically ask for samples of previous power bills when designing a system. These power bills help us estimate your power requirements, and design a system that matches your specific needs. Some months you might use more energy than your system produces, and some months you might use less energy than you produce, but at the end of the year, the goal is to generate about the same amount of energy as you use.
That said, there are some instances where it makes sense to install more solar panels to generate more energy than you plan on using. The first is if you plan on installing an energy storage system to capture that excess energy. Solar battery storage lets you use the energy you generated during the day to power your home at night, and also gives you a backup source of power in case you have a blackout or other issue.
Another time that you might want to generate more power than you plan to use is if your utility offers a strong net metering benefit. Net metering is when the utility gives you credit for the extra electricity that your solar power system produces and then feeds back into the grid, and this can help offset the cost of any electricity that you pull from the utility when your system isn’t generating electricity, like nighttime or during large storms.
In general it’s not possible to install too many solar panels (as long as your roof has space for them) but there just might not be a significant advantage to doing so.
How To Put Solar Panels On Your Roof
Your home’s roof space is just one of the factors that determines the optimum solar power system for your family’s needs. The arrangement of panels and the difficulty of the installation is determined by your roof, but you also need to consider your family’s energy needs, any future changes that your family might expect, your local incentives and net-metering programs, and a variety of other factors. Fortunately, Palmetto can help figure out the precise number and type of panels that will work best for your roof, and make it easy to get a system that’s perfectly matched to your family’s needs.
To find out how many panels you can put on your roof, get started with a free solar estimate, and a Palmetto solar expert will help design a system that’s just the right size to meet your energy goals.
Is My Roof Strong Enough for Solar Panels?
Installing a solar system on your roof is a great way to take advantage of underused space. While roofs provide the obvious benefits of keeping us safe and dry, we can’t use them for much else. With a solar system, however, you can use the space to create cost-free and emissions-free electricity.
If you’re considering installing a solar system, you may be questioning whether or not your roof can actually support the additional weight. That’s a valid concern, and we’re here to help.
How Much Do Roof-Mounted Solar Panels Weigh?
When it comes to the exact weight of a solar panel, it will vary from brand to brand and model to model. While solar panels are not extremely heavy, they’re built solid to withstand all kinds of environmental pressures.
Most 60-cell PV solar panels are somewhere in the range of 35 to 45 pounds, with the majority settling around the middle of this range at 40 pounds. This weight is spread out over the full surface area of the panel. At roughly 5.5 feet by 3.25 feet, a solar panel ends up being around 2.3 pounds per square feet.
72-cell panels will weigh a few more pounds, but because the weight is spread out over a larger surface area, the weight-per-square-foot is about the same. The average weight of a 72-cell solar panel is just over 50 pounds. With a rough dimension of 6.6 feet by 3.25 feet, which ends up being 2.4 pounds per square feet.
Typically, either 60-cell or 72-cell solar panels are used for residential solar installations, but only 72-cell panels will be used on commercial installations.
At Paradise Energy, we offer our customers three brands of solar panels we’ve found to be the best combination of performance, quality, manufacturer warranties, and cost. These panel manufacturers are AXITEC Solar, Hanwha Q CELLS, and LG Solar. Here’s a quick look at how much these manufacturers’ 60-cell and 72-cell solar panels weigh:
|Solar Panel Brand Size||Total Weight of Panel||Weight per Sq. Ft.|
|AXITEC Solar 60-Cell||40.8 pounds||2.28 pounds|
|AXITEC Solar 72-Cell||51.8 pounds||2.39 pounds|
|Q-Cells 60-Cell||43.9 pounds||2.27 pounds|
|Q-Cells 72-Cell||51.8 pounds||2.39 pounds|
|LG Solar 60-Cell||38.6 pounds||2.08 pounds|
|LG Solar 72-Cell||44.8 pounds||2.01 pounds|
LG Solar offers the lightest options and they are among the industry leaders in efficiency and quality. However, they will be one of the more expensive options.
In addition to the solar panels themselves, there will also be mounting equipment installed on your roof to ensure the panels stay in place. This racking adds a small amount of weight to the solar system.
Can Your Roof Support the Added Weight of Solar Panels?
In the vast majority of solar installations, let’s say 95%, the existing roof can adequately handle the additional weight of the roof-mounted solar system.
However, we need to be sure your roof falls within that 95%. To do this, a third-party architect or structural engineer will evaluate your building and the solar system that’s been designed for your property. If they find that the roof can adequately support the weight of the panels, they’ll provide a certified letter stating their approval.
If they find that the roof cannot support the added weight, they’ll recommend what changes need to be made in order to safely install the panels. These could include things like repairing or replacing the roof or adding additional support to the rafters or beams
You and your solar installer will review these changes to see if they fit your goals for the project. If they do, the changes will be made and the revamped structure will be reevaluated. If the structural engineer deems the structure safe, they’ll give their letter of approval and the solar installation can start.
How Will the Weight of Snow on Your Panels Impact Your Roof?
The next question for those of us that live in areas with heavy snow storms is what about the added weight of snow? You can rest assured the structural engineers will take into consideration the average snowfall amounts for your area when they evaluate your structure and the proposed solar system.
Your solar panels and roof will not be affected by snowfall except for rare extreme cases. Solar panels are assigned a pressure rating that measures the amount of pressure a panel can handle before the added weight will hurt the panels. This rating is 5,000 or more Pascals (Pa) for most panels, which allows for the accumulation of two to four feet of snow.
Pro tip: We do not recommend cleaning snow off your panels. Here’s how to take care of snow on your panels.
What Will the Panels Do to Your Roof?
As long as a structural engineer signs off on your solar system, you can trust that the panels overhead are safely mounted to the roof and will not have adverse effects on your roof or building.
Your roof should not leak, assuming the solar panels are installed according to industry-standards. Solar panels can be installed on all types of roofs. Depending on your roofing type, penetrations may or may not be necessary. If roof penetrations are required, extra care will be taken to prevent any leaks.
For asphalt shingles, a piece of flashing is installed beneath the shingle so the lag bolt can be set into the rafter with no potential for leaking.
For corrugated steel roofs, a specifically designed bracket with the same galvanized roofing screws used by roofers in the installation of the roof is used to mount the panels.
For standing seam roofs, no roof penetrations are required. Instead, the panels will be held in place with a clamp that attaches right to the roof’s seam.
For flat roofs, you can opt for a ballast roof mount, which uses the weight of cinder blocks to hold the panels in place. This method does not require roof penetration either.
How Long Will My Roof Last with Solar?
When it comes to the longevity of your roof below a solar system, solar panels should not have an adverse effect. They may actually have a positive effect. If you have a warranty on your roof, your solar installer should double-check with your roof contractor and/or manufacturer to ensure the solar attachments won’t void your warranty.
The solar panels will be installed a few inches above your roof and can act as shields for the roof, bearing the brunt of the elements, from rain to hail to snow. This may help extend the lifespan of the roof.
Solar panels are meant to weather the elements, and manufacturers back this claim up with generous warranties. All solar panels should be guaranteed against specific weather occurrences, like hail up to a certain size and winds up to a certain speed.
However, solar panels aren’t indestructible. Superstorms, hurricanes, and tornadoes can produce extreme weather that falls outside of the manufacturer’s warranty. In this case, your insurance should cover damage to the solar system.
Are Solar Panels Safe on My Roof?
Solar panels can be safely and securely installed on the vast majority of roofs without the need for additional support. However, no solar system should be installed without an architect or structural engineer first evaluating the proposed system and the structural integrity of the building.
Once they have signed off on your installation, you can rest assured that the solar panels won’t interfere with the long-term health of your roof or cause any leaking.
Traditional lighting in your garage consumes energy and leaves behind a hefty monthly bill. With solar installation in Florida, you can reduce your monthly energy expenditure and fully enjoy the comforts of electricity without worrying about skyrocketing bills.
Installing solar panels in your house is the best way to save money and ensure a more comfortable life for you and your family. Read to learn if you can power your garage with solar panels.
Can You Power a Garage with Solar Panels?
You can power a garage with solar panels. First, figure out how much energy the garage uses and what kind of energy it uses. Then determine how many solar panels will be needed to meet the demand. Finally, determine how much it’ll cost and how long it’ll take to pay off your initial investment.
A basic garage needs at least 24KWh of electricity per month to power its machines and 45 KWh to power a detached garage. Solar panels of 300 watts can provide enough energy to operate a detached garage if exposed to sunshine for 6 hours daily.
Solar panels are made of photovoltaic cells (or PV), which convert the energy in sunlight into electricity. You can mount solar panels on rooftops, integrate into Windows, or install them on large-scale ground arrays.
The following steps are how solar panels operate:
- Sunlight hits a solar cell, and photons of light knock electrons loose from their atoms, knocking them into a higher state of energy.
- The electrons flow through the semiconductor and create an electrical current.
- Wires carry the current through an inverter that changes it from direct current (DC) to alternating current (AC).
What Do You Need to Consider Before Installing Solar In a Garage?
Installing solar panels reduces your carbon footprint, but it’s not as simple as just buying some panels, putting them on your roof, and calling it a day. You’re going to want to consider a few things before you start installing solar panels.
- Have the funds available to pay for them before making any commitments; if not, there are ways to finance the purchase through local banks or your bank if they offer loans. It helps spread out payments so that the initial cost doesn’t seem overwhelming.
- The kind of roof. Not all roofs are created equal—some are flat, while others are sloped or curved in some way or another. You’ll need an installer who knows how best to work with whatever type of roofing material yours has so they can install your panels securely and safely without causing damage or leaks.
- The energy amount. Solar energy systems produce a certain amount of energy. If your garage doesn’t need much power, installing a large system with big panels and many batteries might not make sense.
- Condition of the roof. Ensure the roof of your garage can support the weight of the panels. If your roof is older or damaged, it may not be able to hold them.
- The direction of your roof. Solar panels that face south receive the most sunlight, so if you want to maximize your energy production, install them on the south side of your garage.
Advantages of Solar Panels In Your Garage
Here are the best reasons to install solar panels in your garage:
- Energy savings. Solar energy is free, so you can enjoy all the benefits once you’ve invested in solar panels. Not only does it save money on the utility bill, but it will also reduce your carbon footprint.
- Self-sufficiency. With solar panels in place, it means that if there’s an outage or other disruption in service.
- Reduces maintenance costs: Solar panels require very little maintenance since they don’t use moving parts that need replacement every so often; just let them sit there for years without any problems.
- No air pollution: Solar panels do not produce harmful emissions. They do not require any fuel or electricity to operate, so they don’t pollute the air around them.
- Durable: Solar panels withstand extreme temperatures and weather conditions. You can install them in various locations without worrying about damaging them. They can last for 30 years.
- Rebates: Many utility companies offer rebates for installing solar panels on your home or business property. It helps offset some of the costs of installing the panels in your garage.
What Equipments of Solar Panels Do You Need to Run Your Garage
If you want to run your garage on solar power, some equipment items will help you get the job done.
- Solar panel. The panel converts sunlight into electricity and stores it in the battery. A good-quality solar panel can produce up to 30 volts.
- Charge controller. The charge controller regulates the power drawn from the sun and when it gets used by your battery bank or inverter. It also prevents overcharging and discharging of your batteries, which could permanently damage them and render them useless for future use.
- Cable. Cabling connects each panel and runs from each panel to an inverter or battery bank (if you have one). This cable should be rated for outdoor use and be UL listed for safety reasons.
Solar Panels: How Many Fit a Garage?
First, measure your garage’s dimensions: length, width, and height. Know how many hours of sunlight are in your area during the summer months and the amount of energy those hours generate daily. It gives you an idea of how many panels will fit in your garage.
Averagely you need 10–12 solar panels to provide 4000 kWh of electricity annually. The required roof area is 200-240 sq ft facing south.
Solar power is a viable alternative to your standard utility provider if you want to save on your energy bills and prevent pollution. Yes, it was more expensive. Yes, figuring out how to collect the power takes a bit of effort, but the payoffs could be great. There are plenty of solar-powered homeowners that can attest to that. You have to decide whether or not it will work for you. Visithttps://westbayenergy.com/solar-panel-installation/ for reliable solar solutions.
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