What Size Solar System Do You Need?
If you are in the market for solar, you’re probably thrilled with the idea of zeroing out your energy bill. But you can’t just tack a few solar panels on your roof and expect to reduce your bill to nil.
That’s why many customers ask us: what size solar system do I need? The size of your solar system comes down to how much energy you use on a daily basis and how many solar panels it takes to produce that amount of energy.
Some people are surprised to learn that the size of their home is not the main factor in determining the size of their solar system. It’s all about your energy needs.
It’s a common misconception: the size of your home is not the deciding factor in the size of your solar system.
A retired couple that lives in a 3,500 square foot home is likely to use less electricity than a family of four that lives in a 2,500 square foot home. In this case, the family of four would need more solar power to cover their energy demand.
When we are approached by a customer wondering what size solar system they need, we always ask how much electricity they use. You could live in a mansion in Beverly Hills yet your average electricity usage might be less than a suburban family of four.
If you think “my house is small, so I only need a panel or two,” you could be wrong. Same goes for those with larger homes who fear they’ll need a massive, expensive solar system.
Calculating your average daily energy usage is the determining factor in how much solar you need.
To calculate daily energy usage, refer to your past 12 months of energy bills. If you don’t have them handy, log in to your PGE. SMUD. or other energy provider’s account to find your statements online.
Let’s assume that you used 10,000 kilowatt hours (kWh) of electricity in the past 12 months, or an average of 833 kWh per month. Divide 833 by 30 to calculate your average daily energy usage. 833 divided by 30 equals 27 kWh. You can even take the calculation one step further by finding the average energy you use during the summer months, the time of year in which you use the most energy. This value will give you the maximum average energy you use, so you won’t have to deal with energy bills when your usage is more than normal.
But let’s return to our assumed average daily energy usage of 27 kWh. What size solar system do you need in that case? There are a number of factors that come into play. For one, you want to make sure the system you purchase is capable of producing at least 27 kWh of electricity per day. But that’s not all: how much power is generated by your panels depends on where you live and how much shade your home or business gets, since solar panels are rated on the number of kilowatts of energy they produce given 24/7 direct sunlight. Obviously, more shade will knock down the amount of energy your panels can produce.
The chart above shows what a typical day might look like. The yellow bars represent the energy produced by your solar panels. Notice that at midday, when the sun is directly overhead, energy production peaks. As the afternoon progresses and the sun goes down, total energy production decreases. While this is just an example, it’s a good way to visualize solar energy production throughout the day.
Say you’re looking at a solar system that is rated to produce 5 kilowatts (kW) under ideal conditions. In our example, divide 27 kWh by 5 kW and get 5.4 hours, or the amount of time a 5 kW system charging at maximum capacity would need to charge up. If you get 6 hours of sunlight in one day, and your panels produce at peak efficiency, then a 5 kW solar system is large enough to cover your energy needs.
The more intense the sunlight, and the longer you receive direct sunlight, the fewer solar panels you need. But if your roof is partially shaded for much of the day, or much of the roof is at an angle where it does not receive direct sunlight for much of the day, then you will need more panels to compensate.
Compare solar models to find the exact number of solar panels that you need.
Once you figure out the system size you need, you can actually determine the exact number of solar panels that are equal to this energy output.
There are many solar manufacturers with different models. Each solar system model is rated differently. At Ilum Solar, we sell only premium solar systems from reputable manufacturers such as REC. One of our most popular solar models is the REC Alpha 370. a system with a rated power of 370 watts. Divide the system output that you need—in our example, 5,000 watts—by 370 to get 14. In other words, you will need 14 REC Alpha 370 panels in order to generate the desired energy output we previously established.
Go one step further and you can calculate the space that 14 REC Alpha 370 panels would occupy on your roof.
REC Alpha 370 panels measure 5.6 feet long and 3.3 feet wide, or roughly 18.5 square feet. Multiply 14 by 18.5 to arrive at 259 square feet. 14 REC Alpha Panels occupy 259 square feet of space.
Calculating the size of your solar system is not all that difficult. Once you establish the average daily energy that you use, you can pretty quickly work out what size solar system you need in order to generate this power.
Can the right size solar system reduce your energy bill to zero?
Energy are only increasing—rising more than 40% since 1995. The good news? You can completely avoid rising energy costs with solar!
It’s become very clear that solar-sourced energy costs less than traditional energy from the grid. But for some, significant savings is not enough. You might want a zero dollar monthly energy bill, and think solar is the way to achieve it.
Solar will reduce your energy bill. However, only in those months with particularly high energy production relative to energy demand will you see your bill reach zero. Even with the right size solar system, most months your energy bill won’t quite be zero.
That’s not to say your monthly energy costs won’t significantly decrease — they will.
As we mentioned above, peak solar production can only occur with direct sunlight. Sure, if your solar panels had direct sunlight for 8 hours a day, you should expect no monthly energy costs. The reality is that you might get an hour or two of direct sunlight per day, which means an hour or two of peak production.
Most homeowners use electricity during the evening after work. Lights, kitchen appliances, TV, laundry machine, and air conditioning might be running at the same time. But because it is now 6pm and your panels are no longer receiving direct sunlight, you might have to tap into the energy grid to meet your energy demand. That’s why your monthly bill is not zero, even though your solar system is sized correctly.
You can cover at least some of your evening time energy demand to shave off more money from your energy bill with a battery storage system. which is a great way to store and use the excess energy that your panels generate.
The bottom line: solar will decrease your monthly energy costs. How much depends upon your system’s production versus your energy demand. Installing the right size system will get you as close to zero dollar bill as possible.
Determining the size of your solar system is the first step in the solar buying process. While you’re shopping around for a solar company and looking for system quotes, you can make more informed decisions if you calculate what size solar system you need. Once you engage with a solar company, they will also run some calculations to figure out how much solar you need, to ensure you get the perfect system for your home or business.
Have more questions? Contact Ilum Solar! Our staff of engineers can help you determine the size of your solar system and answer any other questions you may have.
kW Solar System UK: Price, How Much Does It Produce, How Big, and
An 10 kw solar system for the right home or business should save around £54600 over the course of its expected 25 year lifetime. That’s based on grid electric costing £0.34/ kWh (last updated October 2022). That’s roughly £2183 per year in savings, without taking into account inflation or rising electric (which both add to your savings if you invest in solar soon).
Rising Electric Costs
The cost of electricity in the UK has consistently ‘outperformed’ inflation. You can see the last few seasons of price rises in this chart of Ofgem’s price cap rises:
The amount that electricity costs continue to rise will have a large impact on whether you decide if solar is worth it for you in the UK.
Smart Export Guarantee
The Smart Export Guarantee replaces the older Feed in Tariff scheme. It allows you to get paid for excess energy that your 10 kw solar system produces but you don’t directly use yourself, for example if you’re out during the day when it’s sunny.
Currently you can expect to get up to 15p per kWh of electricity you ‘export’, so for a 10 Kw solar system, with typical usage patterns, you could expect to receive around £765 per year in payments under this scheme. This rate is available at the time of writing from Octopus Energy.
One of the main reasons to consider getting an 10 kW solar system is to save money by directly using the electricity it produces during the day, instead of paying the utility company. The more of your own ‘self generated’ electricity you use instead of buying it or paying for petrol if you’re also buying an electric car, the higher your savings.
With a properly sized 10 kW solar system, you can expect to save around £1418 per year by using your own solar energy.
kW Solar Panel System Price
An 10 kW solar system (without a battery) typically costs around £12000 in the UK. That’s including installation and VAT.
You can get a free quote from Honest Quotes to get an exact price. They offer a Zero Upfront Cost option for those that qualify.
Get a quote for solar and or battery installation across the UK from our partners Honest Quotes.
How Much Power Does A 10kW Solar System Produce?
One of the most common questions asked by customers is, “will a 10kW solar kit be enough to power my home?” For the average home in the USA, the answer is probably yes, but it will depend on several factors.
So first let’s understand how a solar system is sized and what that means. We’ll look at four topics to answer this question:
- How power is measured in kW vs kWh
- How is the size of the solar system calculated
- What does the solar system produce
- How to work out the benefits and savings
Now let’s take a look at each topic in more detail.
What is the difference between power kW and energy kWh?
A KiloWatt, or kW, is the power used by an appliance or produced by the solar kit. 1kW is one kilowatt or one thousand watts. Most homes can accept from 24,000 watts to 48,000 watts of power from the utility at any moment. For example, if your home has a 100 Amp electrical panel that can handle up to 240 Volts, then the house can accept up to 24,000 watts (100A 240V) of power from the utility at any moment. 10kW is 10,000 watts. If a microwave oven requires 1,000 watts, then 10kW would power 10 microwave ovens running at the same time. That is probably more power than you’ll need at any one time.
Now, a KiloWatt Hour, or kWh, measures energy as kilowatts are used over an hour. 1kWh is one-kilowatt hour, or one thousand watts for an hour. Your utility bill is measured in kWh every month. The average home uses 30kWh per day or 916 kWh per month or 11,000 kWh per year.
kW and kWh is the difference between power and energy. So when you buy your energy from the grid, you buy the kWh.
How is a system size calculated?
Solar Panels are established by their power rating. However, this does not mean they will produce that power at all times. The rating is established in a factory environment under ideal conditions. Throughout the day, as the Sun and seasonal factors change, the amount of power (kW) generated by the solar panels will vary.
To estimate your solar system size, you will need three pieces of information to calculate the solar kilowatts.
Your utility power bill for the last 12 month.
Some power bills have a summary chart. You might find your kWh there. The summary chart may show the average daily kWh used for the past 12 months. If so, you can enter the total kWh for the year. If no total is provided, then add the kilo-watt hours for each month.
The solar hours per day for your location
See our Calculate Solar Page to find your state and nearest city for the solar hours.
The percentage amount of the power bill you want to be covered
The amount of your electricity bill you want to cover. 50%, 80%, 100%, 150%; It’s up to you.
Our Calculate Solar Page has the power calculator ready for you to use with just a few simple steps!
What will the system produce for my home?
Your solar array will produce energy based on what the environment is providing. If we use the 10 kW solar kit example, sometimes the kit will produce less than 10 kW, and other times, it may provide more than 10 kW.
You buy your energy by the kWh, which is important to remember when looking at what the solar kit will produce for your home. The energy produced at a specific moment in the day is less important than the kWh produced over the course of the month, season, or year.
Looking at a 10 kW solar kit, you can expect it to produce 30 to 45 kWh daily or approximately 11,000 to 17,000 kWh over a year. The energy produced will vary with the weather (sunny vs. cloudy day), the season (summer vs. winter), and the location (Florida vs Ohio).
Is a 10 kW Solar Kit the same in Florida as in Ohio?
The average solar hours per day in Ohio is approximately 4.68 hours, while in Florida, it is 5.77 hours per day. Therefore, residents in Florida experience longer solar hours each day, giving them more time to capture solar energy. While residents in Ohio have a smaller window of time for solar hours each day, they need to maximize their potential to capture energy within a shorter time frame.
Living in Cleveland, OH, there are 4.68 solar hours in the day. If the home uses 13,000 kWh per year, then a 10 kW solar kit will meet this home’s needs to cover 100% of the power bill.
However, living in Miami, FL, there are 5.77 solar hours in the day. If the home uses 13,000 kWh per year, then an 8 kW solar kit will meet this home’s needs to cover 100% of the power bill.
This means that in Florida, homeowners can use an 8 kW solar kit to capture the same amount of energy that a home in Ohio needs a 10 kW solar kit to capture. When determining the size of a solar kit, your location and energy requirements are major considerations.
If you buy a smaller solar kit than you need, your solar kit won’t meet your needs. Conversely, the excess energy will be lost if you buy a solar kit that is too large for what you need. You can add a battery storage system to provide power on demand and serve as a backup source in the event of grid outages. The peace of mind will go a long way.
A free way to determine your solar kit needs is to visit our Calculate Your Solar page and follow the instructions. We also have a helpful video to show you how to complete the solar calculator. However, the best way to determine what size of solar kit will work best for you is to purchase a Solar Consultation and Design. The consultation cost is credited back to you with the purchase of a 5kW solar kit or greater. Our experts will assist you by working out all the details to find the best solar kit for your home and budget.
How will my home benefit from the system?
In the perfect scenario, if you use the energy you produce at the time the energy is generated, you would have a zero energy balance. However, what is more likely, is that you are either using less energy than you are producing, in which case you sell energy back to the grid, or you use more energy than you are producing, in which case you buy energy from the grid. Your electricity rate schedule establishes the rate you sell your energy to your electricity company.
If your kit produces 40 kWh per day, this is 14,600 kWh/yr. If you pay 20 cents per kWh (14600 x.20), you will save 2,920 per year having solar. If you pay 30 cents per kWh (14600 x.30), you will save 4,380 per year. If you don’t use half of the energy you produce, and your rate schedule sells energy for 10 cents per kWh, you would receive 720 per year.
The reality is that no one uses all of their solar energy, nor do they sell all of their solar energy. Energy buying and selling are averaged over the course of a year. This is why energy companies reconcile all the cumulative energy charges, credits, and compensation for an entire 12-month billing cycle once a year. So instead of focusing on what your solar kit produces each minute or hour, it is best to see what it produces over a season or a year.
Solar Panel Size Weight: A Comprehensive Guide
Have you ever wondered how big solar panels are? Solar panel size range in a variety of sizes, factors such as solar cell type, total wattage and the type of panel all affect the overall size.
In this article we are going to lay down the foundation and give you all the factors that dictate solar panel size weight. Additionally, we have created tables which give you examples of solar panel size based on wattage and solar cell type.
How Big Are Standard Solar Panels?
Standard residential solar panels, the ones you would have installed onto your homes roof, measure on average 65 inches by 39 inches, or 5.4 feet by 3.25 feet, covering an area of 15 square feet. There are slight measurement variations depending on the solar panel’s manufacturer. For large scale solar installations like the ones built onto warehouses you could expect solar panels to measure up to 6 feet (these are known as commercial solar panels). To understand solar panel size, you need to first understand the general makeup of the panel. Solar panels are made up of smaller individual solar photovoltaic (PV) cells. PV cells always come in the same standard size:156 mm by 156 mm, which is approximately 6 inches long and 6 inches wide. The majority of small scale solar installations, like the ones you are likely to get on your home, are made up of 60 solar cells. Commercial solar installations on the other hand, are made up of 72 cells, and can go up to 98 cells or more.
Solar panel size. residential and commercial panels
|Average Length (inches)
|# of Solar Cells
|Average Width (inches)
|Average Depth (inches)
Essentially, the number of cells found in a solar panel is directly responsible for its length. See below a comparison of residential panels VS commercial panels: Most setups, whether residential or commercial usually do not comprise of a singular solar panel. So what sort of measurements are we looking at with a full blown solar installation, say something like a 10 kW solar system? Let’s assume you use 34 average sized solar panels each with a 300 watt power rating and stack them up vertically next to one another making two rows of 17 panels each. Your 10 kW solar system will measure 55,25 feet by 10.8 feet, covering a total of 596 square feet. Of course, these overall measurements assume that you place each said panel closely next to one another, leaving minimal space in between each panel. In reality however, you will need factor in slightly more area, as you need to take into consideration the unique shape/orientation of your roof.
What is the Average Area of a Single Solar Panel?
Therefore, the average area of a modern single solar panel measures 17,6 square feet.
What Factors Determine Solar Panel Size?
When it comes to the factors that determine solar panel size, you need to consider the following criteria:
Solar Panel Type
As you may well be aware by now, solar panels come in 3 main different types: monocrystalline, polycrystalline and thin-film.
Each one of these different types have their own unique advantages/disadvantages.
Here is a quick table to give you a basic understanding of the differences:
Solar panel type dictates size because of the different materials used inside each of them.
For example, monocrystalline and polycrystalline both use cells made of silicon wafers.
However, the composition of silicon in each type of solar panel varies.
Monocrystalline solar cells are always cut from a single, pure crystal of silicon.
Whereas polycrystalline solar cells are made up of smaller fragments of silicon crystals (which are melted together in a mould before being cut into sheets of wafers).
This difference in composition/makeup of the solar cells themself create slight inefficiencies.
In this case, monocrystalline solar panels are more efficient than polycrystalline solar panels and because of this vary in size.
Take for example two solar panels capable of producing the exact same wattage (take note of the difference in size):
Monocrystalline solar panel dimensions weight – 365 watt
Polycrystalline solar panel dimensions weight – 365 watt
- Dimensions: 2000 mm x 992 mm x 35 mm. Area = 6.56 x 3,25 = 21,32 square feet
- Weight: 49 pounds
Clearly solar panel type has an affect (albeit small in the case of mono vs poly) on the overall size of the solar panel, the more efficient the makeup, the less big the actual panel needs to be.
Solar panel wattage
Solar panels are made up of series of single solar cells, all of which are connected in parallel circuits to form the entire solar panel.
Of course, the higher the solar panel wattage, the more solar cells it needs to achieve that rating.
So ultimately, the more wattage a solar panel produces, the more solar cells it will require. Thus, the bigger the overall panel size.
Are Solar Panels Too Heavy for A Roof?
Let us assume you are installing an average residential solar system on to your roof.
The average weight of a 365 watt monocrystalline solar panel is 45 pounds.
To establish a 10 kW system you will need a total of 28 solar panels mounted on top of your roof.
We know that one 365 watt solar panel weighs 45 pounds and takes up an area of 20,7 square feet.
Therefore, 28 solar panels will take up an area of 580 square feet and will weigh a total of 1260 pounds.
1260 pounds ÷ by 580 square feet = 2.17 pounds per square foot. When you take into account mounting equipment, you can raise the weight per square foot to about 3.5 pounds.
This means a 10 kW solar system (with mounting equipment) will weigh 3.5 pound per square feet.
A modern roof with concrete or clay tiles should be able to support 27 pounds per square foot.
As you can see by these calculations, a 10 kW solar system should have little to no affect on your homes roof, that is, your roof is strong enough to support some of the biggest types of solar panels.
(Please note, our advice should not take the place of a professional solar installation company.)
Here’s another video: What would happen if all the houses were covered with solar panels?
How Much Weight Do Solar Panels Add to a Roof?
This all depends on what sort of solar system you are looking to install onto your roof.
Let us assume you want to install a 5 kW, 10 kW or 15 kW solar system onto your residential home.
First things first, you need to distinguish hoe many watts make up a kW.
The calculation is easy, 1000 watts makes 1 kW. Therefore, you simply have to times the kW by 1000 to figure out the total wattage.
To understand how much weight solar panels add to our roof, we need to decide on what wattage solar panel we want to install. The average residential solar panel produce 300. 420 watts.
For this example let us use a 365 watt solar panel, we already know that they weigh about 45 pounds per panel.
The calculation is as follows: 5000 watt ÷ by 365 watt panel means you will need 14x 365 watt solar panels to make a 5 kW system 14 solar panels x 45 pounds = 630 pounds.
- 5 kW solar system will add 630 pounds to your roof.
- 10 kW solar system will add 1,260 pounds to your roof.
- 15 kW solar system will add 1,845 pounds to your roof.
(Please note, these amounts do not include mounting equipment.)
Examples of Solar Panel Sizes
Average size of solar panels
What Can a 10kW Solar Power System Run?
A 10kW solar power system is one of the largest residential solar power systems you can install in your home. You will need a big roof to fit all the solar panels and an even larger electricity bill to save.
A 10kW solar power system produces 40kWh of electricity per day on average and can run the appliances of a very large 5 bedroom home, including all lights, televisions, laptops, refrigerators, washer, dryer, central air conditioning and a pool pump.
Below is a breakdown of the watt usage of each individual household appliance, its average daily usage in hours and total watts consumed. All of the below can be handled by a 10kW solar system.
What Can You Run With a 10kW Solar Power System?
With the 40kWh per day produced by this system, you can run many electrical appliances in a 4 to 6 bedroom house.
|Lights for 5 bedroom home (10 x 7 watt LED lights [60W equivalent per globe])
|2 x LCD televisions
|2 x Laptops
|Central air conditioner
Note: Daily hours are calculated by taking the average weekly usage and dividing by 7 days. For example with clothes dryer use, 71.8% of households own a clothes dryer, and 74.4% of people use the clothes dryer for every load. With the average house doing 2.5 loads per week and time per load being 1 hour each time, average 2 hours per week and 0.3 of an hour per day. Also, in the chart above, 1 hours is represented as “1”, where 30 minutes is represented as 0.5 hours. Daily watt figures sourced from energyusecalculator.com.
How Much Power Does a 10kW Solar Power System Produce?
A 10kW solar power system produces 40kWh of electricity per day, enough to power two average-sized homes or one large home. An average household in Australia consumes 20kWh to 22kWh of power per day. Therefore, a 10kW solar system is fit for a large house with numerous appliances or a small business of any kind.
If your home is connected to the grid, you will be able to take advantage of a feed-in tariff to send excess power to the grid during the day and draw on it at night. An oversized system will further reduce your power bill as the excess power produced may be more than you draw again at night.
How Much Roof Space Does a 10kW Solar Power System Require?
To install a 10kW solar power system on your roof, you need at least 51 square metres of north-facing roof space.
To produce 10,000 watts of power, you need 30 x 340 watt solar panels on your roof. The dimensions of a typical solar panel is 1m x 1.7m which is 1.7m².
Roof Space needed: 1.7m² x 30 panels = 51m²
Is a 10kW Solar Power System the Best Size for Me?
Choosing a solar system for your home depends on how much power you consume or are likely to consume in the future. For instance, if you are planning to buy an electric car, you will have a higher electricity consumption since you may install a charger for it at home.
If you have a large house with a pool and central air, then you may consume a large amount of power. In this case, the 10kW system may be right for you. If you have low power needs, or have children who will be leaving home in the next few years, 10kW might be overkill.
The best way to calculate the correct size system is to take your last quarterly power bill, divide by 3 to get your month’s power usage in kiloWatts (which you can find on your power bill) and then divide by 30 days. This will give you your average daily usage. If this is around 35. 40kWh, then a 10Kw solar system might be for you. If it is closer to 20kWh, then a 5kW system might be best.
Can You Go Off-Grid With a 10kW Solar Power System?
You can go off-grid with a 10kW solar system whether your daily electricity consumption is equal to or less than the power it produces, and you have enough battery power to store 3. 5 days worth of power.
When choosing to go off-grid with this system, there are some factors you need to consider. First, location. Does the location of your house receive sufficient sunshine for your solar system to produce power effectively and efficiently?
Second, also related to location, is the placement of your solar panels. Are they shaded, or are they in the open to receive sunshine freely?
Invite your chosen solar panel installer to your home before any installation for a free inspection and solar quote. An inspection allows them to identify the layout of the house and available roof space. They can also identify where to place the solar panels for efficient production.
When going off-grid, the most expensive part is the battery storage. As battery technology is still developing, it will come down in cost, but at the moment, you will be paying a high price, and they only come with a ten-year warranty, at which point they will need to be replaced.
There are rebates on batteries in some states like Queensland and South Australia. Still, if you can stay grid-tied for a backup, you will save a lot of money as you will only need to purchase a battery backup to store 70% of your daily usage and draw on the grid if it rains for a week straight.
How Much Does a 10kW Solar Power System Cost?
A 10kW solar system costs from 9,000 to 15,000 with the average Australian paying 10,750. How much you will pay will depend on the solar installer you use and the type of solar panels and accessories you buy. The higher the quality of the solar system, the more you will pay. The skill and installation price charged by your solar installer may also cause you to pay on the higher end of the price range of this system.
How Long Does It Take for a 10kW Solar Power System To Pay for Itself?
It normally takes 3 to 5 years to recover the amount spent purchasing and installing the system. Use this calculator to calculate the payback period of your system here quickly. This is a great ROI as most systems come with a 25-year warranty, so you can enjoy cheap power for years to come.
Is The Solar Rebate Reducing?
The solar rebate reduces by 1/15 every year until 2030, when it will be phased out. Similarly, the price of solar systems is also reducing. The price of the 10kW solar system provided is inclusive of the rebate.
Buy your solar system now to enjoy high rates of rebates and faster payback periods. The longer you wait, the lower the rebate goes. Additionally, the longer your payback period will become.
Does the Location of Your Home Determine How Much Power You Produce?
Yes, it does. Depending on where you live, a 10kW solar system may produce more or less than the expected power. In Perth, a 10kW solar system produces 44kWh, while in Melbourne, it produces 36kWh. At the same time, a 10kW system is expected to produce 40kWh of electric power.
How much electricity your 10kW solar system produces depends on your location and the season. In areas that enjoy more hours of sunshine, the system will produce more electric power than in colder locations. During winter or on days with less sunlight, the system will produce less electricity.
If you’re considering purchasing a 10kW solar power system in 2022-23, you will need a good amount of roof space to mount the solar panels, and to make it worthwhile, your power bill would also need to be considerably high. Perhaps you already own an electric vehicle or are considering purchasing one.