How many solar panels do I need to run my two bedroom townhouse without electricity from the grid?

The issue is more complicated than you might imagine. You can learn how many kilowatt hours you use from your electric bill. This will be an average, but if you want to be off the grid, you will need a system large enough to deliver the maximum amount you use. This will not be practical, unless you have batteries on the system.

My 6 kW system delivers about 20 kWh per day, in an area where the insolation value (suns energy) is about 5. You can find your area’s insolation value on the Internet, under SOLAR INSOLATION.

My installation is situated for maximum utility, in that my ridge runs east and west, and the panels are on the south slope.

Using this information and your utility bill, you should be able to approximate the size system you need.

If your utility has net metering, you may be better off not having batteries, but spend the money on the largest system you can afford. This way you will maximize the amount of savings. Batteries cost money, have to be maintained, must be replaced every few years, and take away from the efficiency of the system.

There are many kinds of solar panels. Look them up on the Internet to learn their characteristics. Keep in mind that the system output will be only about 70 to 75 percent of the rated output. This is due to inefficiencies in system components.

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Ed says:

June 16, 2010 at 1:33 pm

The issue is more complicated than you might imagine. You can learn how many kilowatt hours you use from your electric bill. This will be an average, but if you want to be off the grid, you will need a system large enough to deliver the maximum amount you use. This will not be practical, unless you have batteries on the system.

My 6 kW system delivers about 20 kWh per day, in an area where the insolation value (suns energy) is about 5. You can find your area’s insolation value on the Internet, under SOLAR INSOLATION.

My installation is situated for maximum utility, in that my ridge runs east and west, and the panels are on the south slope.

Using this information and your utility bill, you should be able to approximate the size system you need.

If your utility has net metering, you may be better off not having batteries, but spend the money on the largest system you can afford. This way you will maximize the amount of savings. Batteries cost money, have to be maintained, must be replaced every few years, and take away from the efficiency of the system.

There are many kinds of solar panels. Look them up on the Internet to learn their characteristics. Keep in mind that the system output will be only about 70 to 75 percent of the rated output. This is due to inefficiencies in system components.

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How many solar panels do I need to run my two bedroom townhouse without electricity from the grid?

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