Solar Power FAQs

This is a database of frequently asked questions (FAQs) for homeowners about home solar electricity. Don't see an answer to your question? Submit your question. We'll send an answer and might even add your question to this page!

Solar Power Basics

How much sun do I need?
How long do solar electric systems last?
If the power goes out, will my solar system keep making energy?
Can I sell extra energy back to my utility company?
Can I add panels later?
Can you install solar on multi-unit buildings?
What's the typical voltage of a solar panel?

Solar for my Home

What size system do I need?
What if most of my utility bill is comprised of natural gas charges?
What if I just moved and I don't know how much energy I use?
Will solar increase my California property taxes?
Can my homeowners association (HOA) in California stop me from installing a solar electric system?
What happens if my neighbor's trees block my panels?
How does solar affect my home's value?
What kind of roof do I have to have?
How much roof space is required?
How much weight will the solar electric system put on my roof?
My roof has dormers/gables. Can I still install solar?

Costs, Savings, and Rebates

What is a payback period for solar?
Will the California solar rebates expire?
How long can I reserve the rebate before installing the system?
What's new for home solar electricity in the American Recovery and Reinvestment Act of 2009?

Solar Maintenance

What kind of maintenance is needed for a solar system?
How frequently should I clean my solar panels?

Solar and the Weather

What's the best weather for my solar system?
What happens in rain and fog?
What happens when it snows?
What happens to solar panels in hail?
What happens if lightening strikes a solar panel?

How much sun do I need?
The more sun your solar system gets, the better return you'll get on your money. We can often tell by looking at a satellite image if your roof gets enough sun to make solar cost-effective. Other times you have to get an onsite consultation to have someone check out your roof in person.

How long do solar electric systems last?
Most solar systems are predicted to last anywhere between 25 and 35 years. Most manufacturers guarantee that, in 25 years, your panels will make 80% of the electricity they did in the first year.

If the power goes out, will my solar system keep making energy?
No. For safety reasons, your solar system will automatically shut off if the power goes out. You can get around this by having a battery backup or a generator, though they aren't usually recommended.

Can I sell extra energy back to my utility company?
Yes and no. 44 states have net metering policies which means you can get "roll over credit" if your system makes more energy than you use. But, very few utility companies in the U.S. will cut you a check if you make more energy than you use over the course of a year.

Can I add panels later?
Adding panels is possible but it can be complicated. Inverters and solar panels are designed to "fit together" like puzzle pieces. Because there's an ideal number of solar panels that should be hooked up to a specific inverter, a whole mini system - solar panels and inverter - would most likely need to be added if you want to add panels. And, you'd probably need to add at least 2kW. In many cases it's better to oversize your system a bit if you think you'll need more electricity in the next few years.

Can you install solar on multi-unit buildings?
Yes, but it may be too complicated to make financial sense. Each utility meter needs a separate solar system. So, if the units are small and each has a separate electricity meter, it may not be cost-effective.

What's the typical voltage of a solar panel?
The voltage of a single panel is usually between 20 and 60 volts. When solar panels are wired together in a high voltage string they have an open circuit voltage between 200 and 400 volts.

What size system do I need?
The solar system size you need depends on how much electricity you use.

What if most of my utility bill is comprised of natural gas charges?
Solar electric systems offset only the electricity part of your utility bill - it won't help reduce your natural gas bill. If you're paying over $100 or $150 per month for electricity only, then solar makes a lot of economic sense for you.

What if I just moved and I don't know how much energy I use?
If you can wait just two or three months to see how much electricity you use, that helps us figure out what size solar electric system you need. Sometimes having the old homeowner's electricity usage can help too.

Will solar increase my California property taxes?
No. Section 73 of the California Revenue and Taxation Code provides a property tax exclusion on most types of solar systems, including home solar electric systems.

Can my homeowners association (HOA) in California stop me from installing a solar electric system?
No. The California Solar Rights Act says that homeowners associations (HOAs), governments, and other organizations can't stop you from installing a solar system.

What happens if my neighbor's trees block my panels?
In California, the Shade Control Act prevents others from blocking your access to the sun.

How does solar affect my home's value?
Solar can significantly increase the value of your home. An ICF Consulting study concluded that saving $1 every year on energy costs adds $20 to a home's value.

What kind of roof do I have to have?
You can put a solar system on almost all roof types including composite, wood shake, cement tile, S-tile, tar & gravel, and metal. It may be more expensive to install a system on some roof types than on others.

How much roof space is required?
For every kilowatt (kW) installed, a solar system takes up about 100 square feet, so an average solar system takes between 300 and 600 square feet.

How much weight will the solar electric system put on my roof?
Solar electric systems usually add less than four pounds per square foot.

My roof has dormers/gables. Can I still install solar?
It depends on your roof and your electricity bill. A solar system can be built next to gables if there's enough room but the panels have to be far enough away so they don't end up in the shade.

What is a payback period for solar?
The payback for your solar system depends on lots of variables. Your payback could be anywhere between 5 and 15 years depending on how much energy you use and how much sun your roof gets.

Will the California solar rebates expire?
Although the rebates aren't set to expire at any specific time, the money is being used up. The California solar rebate program began in January 2007 and is funded for $3.2 billion of solar rebates. This money was supposed to last ten years but it's being used faster than expected. Plus, in California, rebate amounts decrease as more solar electric systems are built. So, unfortunately, the best time to install a solar system has historically always been "yesterday."

How long can I reserve the rebate before installing the system?
In California, you have a one year window to install your system. This means your system needs to be up and running within one year of when you originally submit paperwork. If you're building a new home, you get a year and a half.

What's new for home solar electricity in the American Recovery and Reinvestment Act of 2009?
The economic stimulus bill signed by President Obama in February 2009 is unlikely to affect the vast majority of homeowners looking into solar electricity. The bill includes two main provisions that affect the solar electricity industry. First, it allows businesses to receive a cash grant instead of the federal investment tax credit. Second, it confirms that homeowners who go solar using municipal financing can receive the federal solar rebate. To learn more, read our post on Sweet Solar Home, the SunRun blog.

What kind of maintenance is needed for a solar system?
Many homeowners think that solar systems are maintenance-free, but this isn't true. Most solar electric systems have no moving parts so they don't have many mechanical problems, but there's regular maintenance that needs to occur and plenty of other things that can go wrong during your system's 25-30 year life. For more, read our solar maintenance section.

How frequently should I clean my solar panels?
With home solar, the solar power your panels produce will vary depending on the season, weather, and how clean your panels are. In certain situations, dust and debris can decrease your solar production by 5% to 15%. This would most likely occur in special situations, such as a forest fire near your home. Most debris that gets on your panels isn't going to severely limit solar production. It's best to clean your panels when you notice a significant drop in electricity production.

What's the best weather for my solar system?
The best weather for making the most solar power is a sunny but cool day.

What happens in rain and fog?
It doesn't have to be sunny for your panels to work because it's the UV rays that do the trick. In fog or on a cloudy day, your system will produce 25%-30% of what it normally would.

What happens when it snows?
Right after a snow storm, when your panels are covered, they won't produce power. But because solar panels are installed where there's the most sun, that's where the snow will melt first. Plus, snow easily slides off of panels and the reflection off the white snow can even increase how much power your system makes.

What happens to solar panels in hail?
Most solar panels are guaranteed to withstand 3/4 inch hail balls at 120 miles per hour.

What happens if lightening strikes a solar panel?
Almost all solar panels are designed to withstand lightning.

More Information

• Read about all the advantages of solar.
• Find answers to your questions about SunRun's home solar solutions.
• Contact SunRun to find a solar solution for your home.