Thank you for your interest in solar energy! The information below is designed to make you a more knowledgeable solar customer. If there is something else you would like to know, please reach out to us at email@example.com.
How do solar panels work?
Solar electric panels are made out of photovoltaic (PV) cells. These cells convert light energy from the sun to electricity. An inverter then converts the electricity generated by the panels from direct current (DC) to alternating current (AC), which can be used by the appliances in your house.
What is solar water heating?
Solar water heating systems capture the sun’s energy and use it to heat water or other liquids that transfer the heat to water. Solar thermal systems use a solar collector to transfer heat energy into a water storage tank. This tank is similar to those used by a conventional water heater. Systems generally have a backup heater to ensure that you will always have hot water, even if the sun isn’t shining. The solar co-ops organized with DC SUN are for solar electric (PV) only. Click here to learn more about solar hot water heating.
How do solar panels attach to my roof?
Panels are attached to your roof using a racking system. There are a number of different racking system options depending on the roof type and roof condition. You can learn more about the different types of racking systems here.
The best racking system for your home depends on how your roof is structured and what type of roofing materials you have. Your installer will recommend the type of racking system most appropriate for your property.
This article provides a good explanation of the challenges of attaching solar to row-style houses commonly found here in the District.
Will solar work on my roof?
What if my roof isn't good for solar?
In some cases, your roof may not be suitable for solar. This could be due to the obstructions on the roof (dormers, lots of peaks, chimneys, etc.), the roof’s integrity, shading, or other factors.
If your roof isn’t good for solar you may be able to install a ground-mounted system. You’ll need enough space far away from trees or other objects. Most ground mount systems are made out of a combination of aluminum and stainless steel and are mounted in concrete footings in the ground.
What if I can't put solar on my roof and don’t have space for a ground-mounted solar system?
In 2013, the D.C. Council passed the Community Renewables Energy Act. This bill allows renters, homeowners with shaded roofs, tenants of apartment buildings, and others, to receive the benefits of solar energy by removing some of the remaining regulatory barriers to solar.
Sign up to be notified when a community solar project starts in your area.
How do batteries work with solar?
Most residential solar electric systems don’t have batteries–yet. Systems without batteries are less expensive. They are also more efficient in converting the sun’s energy to electricity. Battery systems lose a small amount of electricity as the current moves through and stored in additional equipment. Batteries probably don’t make economic sense if you have stable utility electric service. They also take up room in your home, can require maintenance, and will likely need to be replaced at least once during the life of your solar system.
If you do want to run some or all of your home when the utility electric service is down, you will need to include a battery bank and additional system components to your solar system to keep the batteries charged and ready for use when the power goes out. If you think you might want to get batteries in the future, tell your installer now.
Does D.C. get enough sunlight for solar?
Absolutely! This is an insolation map that compares the amount of sunshine received by the United States and Germany, respectively. Germany receives significantly less sunlight than the United States, but has nearly twice as much installed solar.
Solar operations and maintenance
How long will my solar system last?
The inverters, devices that convert the DC electricity produced by your panels into AC that is used by your home, have different lifespans depending on the type:
- Central inverters generally last for 10-15 years and will likely need replacement during your system’s lifespan.
- Micro-inverters generally last for at least 25 years and usually do not need replacement during your system’s lifespan.
Will my system need maintenance?
Solar systems have no moving parts, so you don’t need to do much to ensure your system functions properly. You don’t need to clean your panels regularly, since they are “washed” by rain. We don’t recommend that you remove snow from your panels. Your panels will heat up and the snow will slide off after a day or so.
Do systems come with warranties?
There are three kinds of warranties relevant to your solar system: product warranties, production warranties and installation warranties.
Product warranties guarantee the physical integrity of the modules and other system components. For example, if one of your modules has a soldered connection fail, causing it to stop producing energy, it would be replaced under the product warranty.
Most solar modules have a 10-year product warranty. Some high-end modules feature product warranties of 25 years or more.
Inverters, devices that convert the DC electricity produced by your panels into AC that is used by your home, have product warranties from 10 to 25 years. String inverters may need to be replaced after 10 to 15 years. Some manufacturers offer the option of purchasing extended warranties for your inverters.
The energy production warranty generally guarantees that a functioning module will produce at least 80% of its originally rated capacity for 25 years. While the details vary from manufacturer to manufacturer, this type of warranty provides assurance that your system will continue to produce power over its lifetime. In practice, identifying whether your system is experiencing a drop in performance that violates this warranty is difficult without the troubleshooting help of an installer. Despite that, production warranties are still a proxy for the expected performance degradation for your solar modules over time. Most solar modules have a 25-year energy production warranty. Some high-end modules feature warranties of 30 years.
Installation warranties cover the workmanship of the installer and includes such things as the roof penetrations they make to attach your system to the building and the electrical wiring work. The length of installation warranties will vary from installer to installer but generally range from three to 10 years. Some installers will offer warranties as long as 20 years.
What happens if my solar panel manufacturer goes out of business?
Most solar manufactures now offer 10-year product warranties and 25-year power production warranties. These protect you from system failures and guarantee your solar systems will produce 80% of their rated capacity after 25 years. But what happens when your panel manufacturer goes out of business?
Unfortunately, unless you take extra steps, your warranty will likely no longer be valid. This is because warranties are considered an unsecured liability under the law. However, there are a few things you can do to prevent a loss of warranty protection should your panel manufacturer go out of business:
- Buy an extended warranty: If the manufacturer goes bankrupt, extended warranties offered through the solar panel retailer are a contractual agreement between the retailer and the consumer, which makes them legally valid. However, you are still out of luck if your manufacturer and your retailer both go out of business.
- Buy from a warranty-insuring manufacturer: Probably the best way to protect yourself from a manufacturer going out of business is to buy panels from a manufacturer who provides third-party insurance for your panels (example). If the company ever goes out of business the insurance ensures that their warranties will still be honored by the insurer.
What happens when it’s cloudy?
When you install a solar system, you’re still connected to the electric grid. When the sun is shining, your panels generate electricity that is used in your home. At night or when the sun isn’t shining, you get your electricity from the electric grid (just like you do now). The process is seamless and happens automatically. You will always have power to your home.
How might storms or snow impact my system?
Solar systems are robust and engineered to withstand local storm conditions including hail, snow, and high winds. Installers design systems to withstand these conditions. Check out this neat video of testing solar panels to withstand stress.
Snow will block your panels from working, or severely decrease their production. We don’t recommend that you remove snow from your panels. The panels will heat up and melt the snow from your roof quickly. The annual production estimates you were given when you bought your system assume there will be snowy and rainy days.
What happens if the electric grid goes down?
If the grid goes down and you have a grid-tied system, you will lose power as well. This is a safety precaution for utility workers, since solar can send excess energy out on neighboring wires even if the local distribution system itself is not functioning.
- Some brands of inverter offer a backup power supply of 1,500 watts during a power failure and when the sun is shining. This would be enough to power small electronic devices or lighting via an electrical outlet connected to the inverter itself.
- You can also opt to pair your system with battery back up. Should the grid go down, you can power part or all of your home with the energy stored in your battery.
Will going solar impact my insurance?
A report by the National Renewable Energy Laboratory found that most rooftop solar systems should be covered as part of your standard homeowners policy. Contact your insurance company before you install your system to let them know about the addition to your property. You should be sure to verify that solar system replacement costs in the event of damage don’t exceed your current policy coverage limits. Adding solar should not increase your homeowner’s insurance premiums. If it does, you may want to find an insurer that provides discounts to customers that “go green”. The report does note that ground-based solar systems may not be covered and may require additional insurance.
How will solar effect my home value if I want to sell?
The answer depends upon your system’s ownership structure. The appraisal industry is training its workforce to accommodate the growth of solar nationwide. The Appraisal Institute now offers training for real estate appraisers on how to appropriately assess the value of solar and other energy efficiency measures add to a home. Make sure to request a real estate professional properly trained in evaluating the impact of solar when the time comes for your home to be appraised.
If you own the system, it will convey with the home and can help improve its resale value. A study by Lawrence Berkeley National Laboratory found that on average, a typically sized residential solar system adds $15,000 to the resale value of a home. The study included an analysis of more than 22,000 home sales across eight states – nearly 4,000 of which contained PV systems. The home sale data used spanned 2002 to 2013.
If you lease the system, you may have a few options depending upon your lease agreement. It may be possible to transfer your lease as part of the home sale. Or, you may have to pay off your lease before selling your home. You can then include the cost of this pay off in your home selling price.
To learn more about how solar is increasingly being incorporated in real property valuation, click here. If you are a licensed real estate appraiser and would like to learn more about including the value of solar in your appraisals to remain at the cutting edge of your field, click here.
Solar and your roof
Should I repair or replace my roof before going solar?
A solar system should last roughly 30 years. It’s important the roof underneath be in good shape. If your roof is more than 10 years old, we recommend having it evaluated to determine its remaining lifespan. You may want to consider repairs or replacement prior to installing solar. If you need work done to your roof after you install solar, you can pay a qualified installer to remove the system before the roof work and re-install it afterward. Costs for this vary, but typically range between $1,000 and $2,500.
Will I have enough roof space to power my entire home?
Most people don’t have enough space on their roof to offset 100% of their electricity needs. You can still offset a portion of your electricity bill with solar. Generally, a solar system on a typical house will produce about 30-60% of your electric needs (assuming an average consumption of 850kwh/month). But that percentage depends on how much electricity you use.
Your installer will estimate how much solar will fit on your roof. They will also estimate the amount of electricity your system will produce each year. These projections are very accurate, based on several decades of testing by the U.S. Department of Energy.
You can use the website, PV Watts, to estimate how much solar you could put on your roof. Then, you can compare the system’s estimated annual electricity production to the amount of electricity you used last year. This will tell you what percentage of your electric bill you could offset with solar. Click here for a tutorial of PV Watts.
What happens if my roof leaks?
What if my neighbor builds a pop-up?
The D.C. Zoning Commission has ruled (PDF) that home additions such as pop-ups cannot be permitted if the addition would interfere with the operation of an existing or permitted solar energy system on an adjacent home. Solar homeowners will have to demonstrate to the Zoning Administrator that a neighbor’s addition harms their system’s output through a shadow, shade, or other study.
What is the process to get my system permitted?
Getting solar installed
How long does it take to install a system?
It typically takes 1-2 months for your installer to design your solar system and then secure initial permits and interconnection agreements. Once they have secured the proper permits, installers usually only need a day or two on-site to put up your system. They will then need to get final approval from the local government permitting office and secure final interconnection approval from the utility. This can take an additional 1-3 months depending on the jurisdiction.
What should I look for in an installer?
When choosing an installer, you should consider their level of experience, competence, and the products they use. You will also want to weigh their ability to provide you the best service and support before, during and after your solar installation.
All installation crews should have at least one, if not all, of their installation staff be NABCEP or RISE certified. This includes their electricians. You should ask the installer how much experience they have with installing systems that are similar to yours.
You will also want to ask your installer what components they offer and typically install. This is helpful if there is a specific type of component package or offering (e.g., American-made, high-efficiency, ground mount) you value.
You should also research prospective installers by asking for references and looking at review sites such as Angie’s List.
What can I do if my homeowners association says it won't allow solar?
If you are encountering resistance from your HOA, join the DC SUN listserv and let us know. We can help you navigate the process. Often, if you get a number of residents from the same HOA together to go solar, you can overcome restrictive HOA rules.
What if I live in an historic district?
Solar installations in historic districts typically must go through an additional step in the permitting process to ensure the location and method of installation comply with local historic requirements. In some jurisdictions, this review is done within the standard permit review process. In others, it is handled by a separate historic review board. Your installer will be familiar with the requirements in your area. You should expect your installer to work with the relevant review body to secure the necessary permits. The cost for doing so should be included in the cost of going solar.
Paying for your system
How much will my system cost?
This answer will vary depending upon the size and type of system you purchase. A typical medium-sized system costs roughly $11,000. Please note, this figure does not include the 30% federal tax credit.
What type of pay back time can I expect?
Payback time depends upon several factors: size of system purchased, average energy usage, the price of electricity, and value of renewable energy credits. We advise solar customers to estimate a 4-5 year payback time.
What financing options are available for my system?
There are two ownership structures you can use to go solar, direct ownership and third-party ownership. Direct ownership means you own your system outright. Third-party ownership means another entity owns and operates the system. Both structures may allow you to finance your system.
Financing a system you own
Owning the system outright means you see an immediate reduction on your electric bills. You also retain the rights to all of the project’s solar renewable energy certificates (SRECs) and other local incentives. As the system owner, you can take advantage of the 30% federal tax credit if you purchase a system outright or finance it through a loan. Here is an example of a solar loan.
Direct ownership of a system makes sense if you are able to pay for the system in cash, and in many cases if you finance it through a loan. There are numerous loan products available ranging from 1 to 20 years in length. In most cases these loans are unsecured and there are no penalties for pre-payment. Standard solar loan products are available nationally and directly from companies like Admirals Bank and others. New solar loan products are coming on to the market regularly. The most attractive loan can often be a home equity line of credit leveraging the value of your home to improve it with the installation of a clean energy system. The interest rates on home equity lines of credit are often very low and the interest paid on them is usually tax-deductible.
Questions to ask about loan products
- What is the term of the loan?
- What is the interest rate, and is it fixed for the entire term of the loan?
- Are there penalties for pre-payment? (If pre-payments are allowed you can use the additional savings from your energy costs, your federal tax credit and your SREC payments to pay down the loan more quickly.)
- Is the loan secured against my property or unsecured?
- Will the combination of my loan payments and my remaining utility bill be higher, the same or lower than what I pay right now for electricity before solar?
Financing solar through third-party ownership
With third-party ownership, another entity (the installer or a third party) owns and maintains the solar system installed on your roof. You then pay for the power the solar panels produce, typically at a rate lower than what you are paying your utility. This arrangement is called a Power Purchase Agreement (PPA). A similar arrangement, called a solar lease, reduces what you pay the utility by leasing the equipment used to produce that power rather than buying the energy that comes from it. Leasing and PPA options are available from many local installers as well as large national companies such as Solar City, Vivint and Sungevity.
Questions to ask about leases and PPAs
- What is the term of the agreement?
- What is the cost of energy ($/kWh) for the agreement or the monthly payment?
- What assumption does the proposal use for how much my utility electricity costs will go up over time? (The assumption used is usually based on 10 or 20-year historic information, but can vary from provider to provider and even from proposal to proposal. The higher the assumed rate of increase, the better the economics will look in the proposal.)
- Is there an escalator for my monthly payments? In other words, will my monthly payment go up during the life of the agreement? If so, by how much and how often? (If your payment goes up over time, the cost of electricity from your utility has to go up at a higher rate than your solar payment in order for you to make money from the solar system.)
- What are my options if I decide to sell my house before the agreement ends?
- What are my options when the agreement ends?
- How long are roof penetrations warranted?
- Why is this important? An installation warranty describes how long an installer’s work is covered against problems encountered due to the act of installing components on the home (roof leaks for example). Does your agreement cover that for the entire term or for a period less than that?
- Will system components be covered for the life of the term or just for the manufacturer’s warranty length? Are there additional costs applicable if equipment should fail after warranties expire?
- Why is this important? Equipment warranties can range from 10 to 25 years. If you have a 20 year term on your agreement but the inverter (for example) is covered for 10 years what happens in year 11 if it fails? Do you incur additional charges?
- Is there any additional insurance coverage provided by the company in the agreement?
- What are my options if I decide to sell my house before the agreement ends?
- What are my options when the agreement ends?
What are the financial benefits of going solar?
Net metering. Net metering allows you to offset your energy consumption with your energy production. When your solar panel is producing electricity your electric meter runs backwards. When you’re more power than your system generates, your electric meter runs forward. At the end of the month, your final electric bill is your total usage minus the electricity that your solar panels produced.
Federal Tax Credit. This tax credit provides you 30% off the total cost of the system. This is calculated before other incentives. You still have to pay up front for the system, but when you file your taxes you will receive a 30% credit (not a deduction) from the federal government.
Solar Renewable Energy Credits (SRECs). When you generate solar electricity from your system you also generate an associated “green value” for your electricity. This is known as an SREC. Every time your system produces 1,000 kWh of electricity, you get one SREC. These SRECs have a variable monetary value, like a company’s stock or commodity product.
What does price per watt mean?
“Price per watt” is how installers price solar systems. As the name implies, this is the price you will pay for each watt of electricity your system is rated to produce. Each solar panel comes with a wattage rating. This rating is the amount of DC (direct current) power the panel produces under test conditions. So, a panel rated at 300 watts produces that much power output.
A solar system made up of ten 300 watt panels would produce 3,000 watts*. Let’s assume that system costs $10,000. Doing the math, the cost per watt of the system is $3.33.
When comparing different installers’ proposals, it is important to make sure you are making an apples to apples comparison. The price per watt should include the gross cost of the system. This includes all system components such as racking, inverters, etc. It should also include the installation and permitting costs as well. The gross cost does not include the 30% federal tax credit.
*Note: Systems are more commonly measured in kilowatts. One kilowatt equals 1,000 watts, so the above example refers to a 3 kilowatt system.
What if there are problems with my system?
If you find there are issues with your system you should contact your installer and work with them to get the issue resolved. You should have an online monitoring portal available to you. This will show you the amount of energy you generate. You can use this information to verify if your system is still producing energy in the quantity it did before. Keep in mind that energy production fluctuates from day to day, month to month, and year to year based on weather conditions and other factors. Despite those fluctuations, you should see a consistent curve of energy production over time.
What happens if I produce more energy than I use?
It is common for systems to produce more than a home uses during the day when you are not home, using electricity. Net metering is a billing system that ensures you receive fair compensation for the electricity your system generates. It allows residential solar energy generators to offset their energy consumption with their energy production. When your solar panels are producing more electricity than you’re using on site, your electric meter runs backwards. When you’re using more electricity than you system is generating, your electric meter runs forward. At the end of the month, your final electric utility bill is your total usage minus the electricity that your solar panels produced. For more information, check out our net metering page.
I love solar! Does anyone else?
Yes! You’re not alone. In addition to providing troubleshooting, the DC SUN listserv is full of solar enthusiasts, people who have gone solar, and folks that want to make more solar happen in their communities. Join the listserv and connect with other solar lovers!
How can I get more involved in solar in the District?
There are a number of ways to stay involved with solar in D.C. You can help other communities go solar by helping to start other co-ops, get involved in policy advocacy, or even offer your expertise to your friends and neighbors interested in going solar. The first step is to become active is to join the conversation.
You may also want to participate in the DC SUN advisory board to offer you input and voice in the direction in the issues and direction that DC SUN takes.
Solar co-op basics
What is a solar co-op?
A solar co-op is a group of homeowners in a defined geographic area who use their combined bulk buying power to save on the total cost of going solar. Solar installers face significant costs finding solar customers. By forming a group of interested buyers, co-op members can receive a significant discount because the group has done some of the work for the installer. Co-op members also have the benefit of working with a group and with DC SUN to help educate and guide them through the installation process.
How does the co-op purchase work?
DC SUN helps groups of neighbors form co-ops to get discounts on members’ individual purchase of solar systems for their homes. Once the group reaches a critical mass of members (roughly 30 good roofs), it puts out a request for proposals from area installers. Each bid contains a set price per the amount of solar the installer would install on co-op member homes. This allows installers to make individualized proposals to each co-op member. The co-op reviews all bids with the technical support of DC SUN. It then selects an installer to install systems on co-op member homes. Each participant owns or leases their own system and has their own contract with the installer.
What is the benefit of participating in a co-op to go solar?
Solar is a smart investment that lowers your energy bills and increases the value of your home. Going solar with a co-op will help you save money (typically up to 20%) on the initial investment. Most importantly, you will have the support of the co-op and DC SUN throughout the entire process.
Who is DC SUN?
DC SUN expands access to solar by educating District residents about the benefits of distributed solar energy, helping them organize group solar installations, and strengthening D.C.’s solar policies and its community of solar supporters. DC SUN is a project of the Community Power Network, a national network of grassroots local, state, and national organizations working to build, and promote locally based renewable energy projects and policies. The network runs similar state programs in Maryland, Virginia, and West Virginia.