Solar Backup Power - Will My Solar Panels Work in a Grid Blackout

By Jay Ibric
March 09, 2017
Will Solar Panels Keep Working If the Power Goes Out.png

Solar photo-voltaic panels are created to absorb the sun’s energy and convert it to usable AC energy in your home. You may be wondering then, do my panels work when there is a blackout? It’s a great question. The sun is up so my system is producing. Thus, I have energy, don’t I? The answer is? It depends.

All solar systems are tied into the utility grid. The benefit of this is that your system will receive net metering credit. During the day, your panels will produce energy. The excess energy will go into the utilities grid and you will earn credits for this production. Your panels will not produce energy at night but you will be using the credits that you generated during the day. The downside of being connected to the grid is that if there is a blackout your solar system will not work. All grid tied solar systems are installed with an automatic shutoff switch which turns off your solar system is a power outage. This is done as a safety precaution to protect you, your neighbors, and the utility employees from any live wires that may be touched.

Operating Once The Power Goes Out

There are things that can be done if you want your system to operate during a blackout. Because your solar system produces direct current (DC) energy something will need to convert it to the alternating current (AC) that is used inside homes. There are string inverters and micro-inverters that accomplish this task. The SMA SunnyBoy with Secure Power Supply (SPS) is a string inverter that does this AND features a plug-in option. This plug-in is designed to operate under blackout conditions. However, it will only work while your solar system is producing energy. The plug-in will not produce any energy at night if there is a blackout.

This secure power supply will provide up to 2000W of energy. For comparison, a 60W light bulb will use 60W in an hour. Five lights would utilize 300W in an hour. The secure power supply would be able to keep the power running for five lights for six hours (300 * 6 = 1800W) under blackout conditions. This should give you a general understanding of what the secure power supply can handle.

Battery Backed Solar

But what if you want to have more security and energy capability if there is a blackout? There is a solution for that: batteries! A solar system that has batteries will work during a blackout. The reason for this is that the solar system and battery will be wired independent of the grid. There will be no danger to utility employees and your home will have usable energy.

Kyle and Andrew compared the top battery brands: Tesla Powerwall, LG Chem Resu, and Sonnen Eco on Pick My Solar LIVE.

To size the battery properly we will need to know which critical loads you’d like to have backed up. Your solar system will operate during the day and if it not being used to full capacity the excess will go into the battery to be used at night when your system is not producing. Depending on the size of the battery and the energy consumption you may be protected for the entirety of the blackout!

There is also the chance that your power lines may suffer a brownout. This happens when there is a drop in voltage in the electrical power supply. Basically, there is not enough electricity available for everyone. It can be intentional by the utility to avoid a blackout, or unintentional. A brownout may last a few moments or a few hours. Your lights may flicker, some appliance may have reduced performance, and some electronics can be damaged or destroyed due to the irregular voltage. If this is common in your area, or if you want to protect yourself from them batteries provide that level of protection. Batteries will protect the critical loads that are connected to the battery.

So, if one of your main needs to go solar is to have power during a blackout, then there are a few solutions. If you want something that will work but will not add much cost to your array, then the SMA SunnyBoy with SPS is the way to go. If you want true 24-hr backup protection and a larger capacity, then a battery will be your solution!

Jay Ibric

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Jay Ibric

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