Learn what goes into making a home solar-ready, what a solar rough-in is and the ideal home design for solar panels.
If you are builder or homeowner and want to install solar panels or incorporate them into your new home or building, making it solar-ready will save a lot of money when you are ready to install the system, whether that is 5 weeks or 5 years in the future.
Minor investments now often pay great dividends in the future.
What is a Solar-Ready Home?
A solar-ready home is one that has been designed and prepared for a solar power installation to occur in the future.
Building a solar powered home requires a few quick changes from standard construction practices such as completing a solar rough-in, optimizing the roof areas for solar energy generation and of course making the array look good.
Solar-Ready Benefits
The steps required to make your home solar ready are very inexpensive when done during the planning and design stage of the home building process.
If you’ve had much experience with contracting services before, you’ll know that after-thoughts can be expensive.
Improve the Look
Designing a house with solar panels gives the option of integrating the array into the building shape in a complementary way.
Uniform shapes and large arrays can be more pleasing to look at than a patchwork of solar panels. Larger roof faces = larger arrays. Gables, dormers, vents and other obstructions will result in smaller arrays and may result in fewer installed solar panels.
Roughing in a home for solar will hide any exterior cabling by installing the lines behind walls with your other electrical wires. This creates a much cleaner finished product.
If you can’t make a large uniform face, we will still minimize exterior cabling and match the solar panels to the face shape as best as possible.
Better Performance
Building a home for solar panels can greatly improve the output of your system. Minor adjustments to the tilt and azimuth of your home can yield tremendous solar energy gains.
Alterations to roof faces can also make a world of a difference.
Gables, dormers, and ridge lines will all impact the available area for solar.
Prepare for the Future
Maybe you don’t want solar now, but you might in the future as technology improves and drop. Preparing in advance is a wise decision that can save you contracting related stress in the future.
Having a solar-ready home gives you the option of a simple installation whenever you want.
If done with adequate planning, the solar rough-in will also negate any outer wall penetrations that may need to occur otherwise, which is important not only for aesthetic but to minimize risks associated with holes in the envelope.
Even if you don’t wan’t to complete the project, selling a solar-ready home is an added feature that the next buyer may value.
How to Make a Home Solar-Ready
Below are a few solar ready guidelines and technical specifications to consider when designing a home for a solar.
- Design roof areas for solar placement
- Place mechanical obstructions (vents, plumbing stacks etc) away from solar area
- Install conduit
- Electrical panel size and space
- Consider roofing and attic type
If you want to set up a solar system for a home, follow these guidelines.
Design the Roof for Solar
Large rectangular unobstructed areas are ideal for installing solar electric systems. Designing a home and roof for solar is key to maximizing the aesthetic when it comes time to install the home solar panels.
Solar modules are rectangular which make better use of available space on similar shaped roof areas. It is possible to install panels on triangular faces, but there will be more unutilized areas on the face.
Steeper tilts and southern exposures will produce the most energy throughout the year. on this below.
Remove Obstructions
Vents, plumbing stacks, chimneys, satellites, skylights etc can negate the placement of solar panels in those areas or require additional costs to move the devices.
Placing the obstructions away from the solar face will allow more room to place panels. Ideally, the devices can be placed on faces that won’t have solar panels, but this is not always possible.
If obstructions have to be placed on the face, grouping them together and near the crest, eave or edge will maximize the available space for installing solar panels on a new home.
Install Conduit for Solar Panels
Conduits for solar power systems are simple to install and will provide the benefits detailed earlier. This is the primary work required for a solar rough-in. It doesn’t seem like much, but this simple step will save hundreds or even thousands of dollars when it comes time to install solar panels for your home or business.
At least 1 x 1.5 conduit should be installed from the electrical room to the attic. The conduit should be metal, rigid PVC, liquid tight flex or metallic tubing and be in a straight line if possible.
Larger homes may need larger or more conduits. When in doubt, increase the size of the solar conduit. The material cost for this is minor.
If a conduit is stubbed in the attic, ensure that the top is above the insulation and has a pull string. Installing an attic access hatch is required (hopefully that is obvious).
The solar rough-in process is very similar whether it is being done for a home or a business, each requiring conduit or cable from the electrical room to the solar panels’ location. The key difference between commercial and residential solar rough-ins is sizing the conduit/cable properly. Since commercial solar installations tend to be larger than residential solar installations, a larger cable/conduit will be required.
Electrical Panel Considerations
Providing a small area near the electrical panel will provide more flexibility should the homeowner want to install a string inverter in the future.
An area roughly 2′ x 3′ is sufficient for routing cabling and installing devices effectively.
Additionally, it is best to increase the electrical panel busbar size relative to the main breaker rating.
Your electrician will know what to do. The main service is protected by a main breaker, most often 100A or 200A. The panel itself has a different rating (determined by the size and thickness of the metal plate in the panel, called the ‘busbar’). It is best to make sure the busbar/panel rating is higher than the main breaker rating. This will allow one to maximize the amount of solar power.
For future planning, it may be safest to increase the service size as well from 100A to 150A or from 150A to 200A. This will come in handy if an electric vehicle, hot tub, AC unit or other high-draw device is desired in the future.
Remember, if you increase the service size to 150A or 200A, increase the panel size to 200A or 225A respectively.
Roof and Attic Considerations
What roof type is installed may impact how to make the home solar ready.
It is common practice to install a solar-specific junction box which sits on the roof, but is flashed/weatherproofed. Cables are routed through this junction box into the attic/home so no cables are visible from anywhere on the ground.
Asphalt shingles can easily be worked with at anytime in the future, but other roofs can be a touch trickier.
Standing seam, corrugated, and metal shingle roofs can often benefit from having a junction box installed prior to/during the roofing stage. It is possible to retrofit this in, but it will be easier and more cost effective during the initial construction.
Metal shingle roofs may require additional support from your solar company and roofing company to install the racking supports. Once again, this is best done during the initial construciton/roofing stage to ensure the roof is sealed and all warranties upheld.
If the home is to have a vaulted ceiling (no attic), then additional measures should be taken to make sure cables can be routed internally. Simply putting in a conduit will not suffice here. To rough in a home for solar with a vaulted ceiling, the roof-level junction box should be installed and the cables or conduit connected on the interior side.
Solar Ready Guidelines
Natural Resources Canada has produced a set of solar-ready technical guidelines. Use these specifications in conjunction with the tips we have laid out here and always contact us if you have any questions or concerns.
Ideal Solar Home
Planning for solar during the design stage of a build is the best time to do so. In the end, you will have a far more optimized solar power system if you plan ahead.
The ideal solar home will have a large (as large as possible) face with a southern exposure with little to no interference from vents, chimneys and other obstructions.
Solar panels on West and East faces are also applicable, but will result in a slight efficiency loss relative to their south-facing counterparts. Solar panels facing due East or West, will produce at approximately 80% of the energy that the same solar panels would if they were facings south. Other factors, such as tilt, play into the exact efficiency loss from the azimuth, but 80% is an accurate ballpark estimate.
The ideal tilt for solar panels are approximately equal to the latitude within 15 degrees. Designing your home as close to this tilt is ideal, but it is certainly not detrimental if it can’t be done. Most homes are built with a 4:12 pitch, or 18 degree tilt, which is still great for solar energy generation. Steep tilts are great for energy production but may come with added installation costs due to working at difficult angles.
Snow will shed better on steeper tilts which is ideal for off-grid homes or net-zero homes.
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New Construction
Modern technology makes it cost-effective and sensible to build a 100% solar-powered home, with no utility bills and minimal carbon footprint. At ReVision Energy, we’ve helped thousands of homeowners achieve their dream of living in a solar-powered home through new construction, whether we work directly with the homeowner, or with their builder or architect.
This guide is designed for those in the process of building a new home, though many of the concepts apply to existing homes as well. It will cover:
- The many benefits of going solar in New England
- Key considerations to build your new home better (it’s not just about the solar!)
- How solar can power, heat, and cool your new home
- Solar batteries and driving on sunshine (aka EV charging)
- An interactive worksheet to get you dreaming and scheming about your solar powered home
Solar Makes Sense in New England
Maine, Massachusetts, and New Hampshire offer key economic and geographic advantages that make solar a viable option for your new construction.
While most people know that powering your home with solar is better for the environment, many don’t know that solar is a powerful economic benefit too:
- New England’s solar resource is abundant. Each year, we receive the same amount of usable solar energy as Houston, Texas. Our bright, chilly spring and fall and long summers help make up for the dark days of winter.
- The cost of solar panels has declined sharply in the last decade. We’ve seen a steadying decline in costs, driven largely by photovoltaic (PV) module efficiencies (now 19.5%, up from 19.2% in 2019) and hardware and inverter costs. Since 2010, there has been a 64% reduction in the cost of residential PV systems, respectively.
- Solar electricity can be used to heat and cool your home. While it’s great to save money on your electric bill, solar really becomes a valuable investment when used to power heating and cooling equipment, such as modern cold climate heat pumps and heat pump water heaters. By building a tight, well-insulated home. you reduce the need to build an expensive monstrosity of a heating system, freeing up funds to pay for the heat pump and solar combo (more on that shortly).
- Solar panels are incredibly reliable. Solar panels come warrantied for 25 years and are expected to have a service life of 40 years. With no moving parts, a solar panel system is one of the most reliable, long-lived mechanical systems you can invest in.
Before Solar, Build it Better
Building a well-insulated and efficiently ventilated house will set you up for greater success when powering your home with solar.
The most important advice we have doesn’t even pertain to solar…it’s about the house itself. Build it better!
While building codes have gotten tougher around energy efficiency, we still think that a code-built home is far below the minimum insulation/air-tightness that any reasonable person would want. It really doesn’t cost that much more money to build a tighter, better-insulated home, and the effort to do so will result in huge savings down the road, in terms of energy bills you don’t need to pay and carbon pollution you’ll keep out of the atmosphere.
There are lots of nuances to this, but we’re generally fans of building at least to a “Pretty Good House” standard. Since this term was thought up, there have been numerous resources and guide published about how to build a Pretty Good House. We recommend you check those out!
Pretty Good House standards:
- Well-insulated (R20) basement or slab
- R30-40 wall system, such as 2×6 walls with dense pack cellulose for thermal resistance and 2 inch of rigid foam to eliminate thermal bridging (even better to do a double-stud wall system!)
- R60 attic insulation
- Better than average air sealing (easier said than done, as many trades on a jobsite need to have air sealing literacy for this to be successful. For example, choices in the framing process matter in terms of air sealing, and electricians/plumbers can screw up a really good air sealing job!)
- High-end double-hung Windows, or triple-glazed Windows
- Mechanical ventilation (without this it’ll be hard to breathe in your tight new house. more on this below!)
For context, a home built to this standard may command a 26% cost premium over a barely-meets-code build home, but will use roughly ½ as much energy. It’s worth remembering: A code-built house is literally the worst house you are legally allowed to build in your region… A far cry from the best! (Thanks to Emily Mottram for this particular line)
Ventilation is Crucial
New construction requires a mechanical ventilation strategy. The more air-tight and insulated a home is, the less energy needed to heat and cool it. Naturally, such a house will also “breathe” less; to be a healthy environment for people and pets, every house needs to be able to exchange stale air for fresh outdoor air.
Building codes in most states mandate that one third of the stale air inside a home should be replaced with fresh air from the outdoors every hour, also known as the baseline Air Exchange Rate (ACH) of.3 ACH per hour.
Older, draftier homes do this by leaking air from walls, doors, Windows, attics, and basements. However, as you might imagine, they lose an awful lot of heat in the process. The solution is to “build tight and ventilate right.” A Balanced Mechanical Ventilation system ensures that the right amount of potentially toxic indoor air is replaced with precisely the same amount of fresh outdoor air each hour. Energy Recovery Ventilation (ERV) and Heat Recovery Ventilation (HRV) systems improve on this concept by extracting heat from the outgoing stale air, keeping it inside the house. Thus, the needed air changes can occur with minimal loss of BTUs!
There are several configurations and brands of ventilation systems, which have varying levels of efficiency. The least efficient will only preserve around 50% of the heat from the exhaust air (and often even less if improperly installed). At ReVision, we only work with the best products in every technology, and exclusively install Zehnder Energy Recovery Systems.
Zehnder, based in Italy, is a leading manufacturer of ventilation equipment in Europe, where standards for energy efficiency have been higher than in the US for some time. The ComfoQ ERVs from Zehnder offer up to 90% efficient heat recovery – significantly more than most domestic ventilation systems.
Our team would be happy to guide you as you consider ventilation systems for your new construction.
Built it in the Right Direction
The location, orientation, and design of your roof is a key factor in building your solar powered home. if you’re planning on rooftop solar, of course.
The roof matters!! Some decisions around how you design and orient your home can have big impacts on solar. Some key considerations:
- Everyone knows that the sun rises in the east and sets in the west… But did you know it tracks along the southern skyline as it does so? This is why solar panels (in the Northern Hemisphere) get oriented to the south. The sun is relatively higher in the skyline during the summer, and relatively lower in the wintertime, as seen below.
- “True” south in New England is 195 degrees on the compass (slightly west of magnetic south). An ideal solar roof will be designed to face this true south.
- NO SHADE – Shade trees (or other obstructions) have a serious negative effect on solar production.
- A perfect solar array will be on a pitched roof (6/12 to 12/12) facing /- 15 degrees of true south.That said, solar panels will produce up to 90% of their rated output even at more east and west orientations, so if your future home’s site makes a southerly orientation impossible, it doesn’t mean solar won’t be a great investment.
- Simple roof layouts (minimum dormers, plumbing vents, chimneys, etc) are much better for solar. Put plumbing vents and chimneys on the north side of the roof, if possible.
- If you absolutely can’t design your roof in such a way that it is compatible with solar, you can install solar elsewhere! We have ground-mounted solar, dual-axis solar trackers, and solar canopy options available.
Powering your New Home with Solar
Finally, the good part! There are different ways to go solar (off-grid, grid-tied, etc.) but for this guide, we’re going to assume you’re going with a grid-tied solar options. Here’s why:
- 99% of solar installations in the US are grid-tied, meaning they still have a physical connection to the public utility grid, but can also produce their own solar power.
- Under this arrangement, you treat the utility like a gigantic battery – anytime the sun is out, your home produces and consumes its own solar electricity, but any excess you can send out to the grid. At night or during crummy weather, you use power from the electric grid like normal.
- Utilities are required by law to give you credits for any solar power you send out to the grid, under an arrangement called ‘net metering.’ In most places, you get a 1:1 credit, or 1 unit of exported solar = 1 unit of utility credit you can use later.
- The best of both worlds, is have a grid-tied solar array (which allows your solar to produce as much power as it possibly can with no limits) with battery backup (so that if the grid goes down you have source of backup power). ReVision offers modern battery backup solutions, such as the Tesla Powerwall.
In a grid-tied solar electric system, with or without battery backup, the goal is generally to achieve net-zero, meaning, at the end of the year your home will have produced as much electricity as it has consumed. This is not always possible (especially if you’re heating with solar and also running an electric car) but it’s a worthy goal!
“Plug Load” Electricity Estimate
Before we get into heating and cooling, we start with getting an estimate for ‘plug loads’ — the amount of power you need for your household appliances, electronics, well pump, etc.
This is tricky! No two families are alike, and two families living in the same home can have VERY different electricity bills depending on occupant behavior. Once you start to work with a ReVision Solar Design Specialist, we’ll do a more thorough analysis, and ideally get a professional energy designer in the mix to build a more complex model. Some useful terminology for you to know:
- Electricity is measured in units called kilowatts (1,000 watts). This represents instantaneous power – much like miles per hour measure the speed of a vehicle, but not its travel over time.
- Electricity is billed in units called kilowatt-hours. This is the amount of total energy as an expression of kilowatts and time. This is like measuring how many miles a car traveled, and averaging the miles-per-hour over that time period.
- Solar panel arrays are usually sold in kilowatts (the ‘nameplate’ rating of the panels in full sun) but its far more important to understand how much energy they will produce over time – or their kilowatt-hour (kWh) potential.
- Each 1kw of solar panels (roughly 3) = 1,200 kWh a year of solar production on a decent solar site in our region.
Heating Cooling your Home with Solar
Modern heat pumps are fundamentally more efficient than older technologies like baseboard heating and air conditioning and a great option for new construction.
Do you dread the idea of putting a noisy, fuel-sucking heater or boiler into your new home? Well, good news! Your solar-powered home of the future needs no oil or gas at all. Modern heat pumps, which can be powered by solar, are the best option for you newly constructed homes (old homes too, for that matter).
Cold-climate heat pumps work by using a refrigeration process similar to the way your home’s refrigerator works. Warmth is extracted from the ambient outside air (down to temperatures around.15F) and transferred into your home. Since the heat pump is moving, not creating, heat, it is highly efficient. Powered by solar, a heat pump can heat your home for the equivalent of around 1/gallon for oil!
Heat pumps also replace the need for air conditioning. In warmer months, heat pumps extract hot air and humidity from your home, for less than what a typical air conditioning unit costs to generate cool air.
While it’s possible to keep drafty old homes warm with heat pumps, they are far more effective when used in a tight, well-insulated house, hence our recommendation that you build one. If you build a good quality house, then you can heat primarily with heat pumps, and install a small backup system (say a pellet stove or electric baseboard) to supplement the heat pumps during periods of extreme cold weather.
Since heat pumps are powered by electricity, you can use solar power you bank in the summertime as your fuel source in the winter.
If you’re planning on building a new home and want to harness the power of the sun to create an energy efficient, climate friendly household, get in touch with ReVision! Use the Get Started button below to contact our Solar Advisor team.
Service
Need support for your existing system? Contact our Service Team: Reach us at (207) 747-0076 or open a Support Ticket.
Our Guide to Building a House with Solar
There are a lot of advantages to building a modern, efficient, and “Smart” home. Pairing efficient building design with the latest technology, like heat pumps, energy efficient appliances, solar, and battery storage can reduce your energy bill significantly, or (if you opt for solar) eliminate it entirely.
Building a new home?
Design with solar in mind!
Solar is a Smart addition for new homes, and SunCommon has years of experience working with contractors, builders, and architects to incorporate solar right into a home’s design. Orientation and design can have a big impact on the efficiency of the solar system, so here are some of the details to keep in mind as you start dreaming-up the plans for your new home. To download our complete guide, use the form at the bottom of the page.
SunCommon offers a classic roof or ground solar array, as well as the timber-framed Solar Canopy, any of which can be paired with an energy storage system.
Orientation to the Sun
An ideal roof for solar has a large surface facing south, southeast, or southwest. For a Solar Canopy or ground array. choose a sunny spot in your yard that’s flat or gently sloped, ideally within 150’ of your home’s utility room or meter.
Obstructions Shading
A wide-open roof is best. Obstructions like chimneys, vent pipes, dormers, and skylights can cast a shadow and limit the space available for your solar system. Tree shading will also factor in, so it’s best to have a shade-free roof from roughly 9 AM to 3 PM.
Roof Structure
To optimize solar production, a south-facing roof pitch between 30 to 35 degrees is recommended, though we can install solar on roofs up to 45 degrees. For east- or west-facing roofs, a pitch between 10 to 30 degrees is best. Any roof 10 degrees or less will require a professional structural review to verify the roof can accommodate the added weight of a system.
Roofing Material
Standing Seam Metal SunCommon only works with mechanical single or double lock standing seam roofs. These roofs are ideal because they will last as long as your solar system (25 years). Our design team can work with your roofing contractor to install junction boxes, which will allow the wiring to be concealed and hidden.
Asphalt Shingles We recommend a 30-year rated shingle. Talk to your contractor about using a minimum of 1/2” OSB or ⅝” plywood sheathing on the roof.
Corrugated Ribbed Metal Solar can only be installed on corrugated and ribbed metal when a minimum ½”sheathing (plywood/OSB) is present. Please get in touch with us before selecting corrugated and ribbed metal and we’ll discuss options that can accommodate solar.
Electrical
Arguably the most important element of any solar design. Please let your electrical contractor know right away that you are planning to incorporate solar into your new build. If SunCommon is involved in the process early on, we can work with your contractor to choose equipment that is preferred for solar interconnections.
There are several electrical components to consider as it relates to solar: service size, main service panel location, utility requirements and existing utility infrastructure. A main breaker is required in the main service panel—no exceptions. Additionally, all projects require exterior utility equipment, such a production meter and system disconnect. For roof mounts, we strongly recommend including a 2″ conduit chase from the attic to the main service panel. To utilize this, our installers need access to your attic, and must have a clear working area by the main service panel.
To learn more and view specifics, complete the form below to download our complete Building a House with Solar Guide, or give us a call at 802-882-8170.
Passive Solar Technology Basics
Passive solar technologies convert sunlight into usable heat and cause air movement for ventilating to heat and cool living spaces without active mechanical or electrical devices.
Passive Solar Design
A passive solar building uses south-facing Windows to collect heat from the sun and stores that heat in materials throughout the building known as thermal mass.
A successful design must include the following elements:
- Aperture —a large glass area through which sunlight enters the building, should face within 30 degrees of true south and should not be shaded between 9 a.m. and 3 p.m. during the heating season.
- Thermal mass—commonly concrete, brick, stone, and tile. These materials absorb heat from the sunlight during the heating season and also absorb heat from warm interior air during the cooling season.
- Distribution— a method by which solar heat is transferred from where it is collected and stored to different areas of the house by conduction, convection, and radiation.
- Control—devices such as roof overhangs used to shade the aperture area during summer months.
Passive Solar Heating
Passive solar heating systems capture sunlight within the building’s materials and then release that heat during periods when the sun is absent, such as at night. South-facing glass and thermal mass to absorb, store, and distribute heat are necessary in the design.
Passive Solar Cooling
Passive solar cooling systems use shading, thermal mass, and natural ventilation to reduce unwanted daytime heat and store cool night air to moderate temperatures.
Additional Resources
For more information about passive solar design, visit the following resources from the U.S. Department of Energy: