Do you have battery backup for solar powered systems? Where are the batteries? That’s one of the most common question I get asked when I tell folks I have a solar powered system on my house. That was the first question a friend asked at a New Year’s Eve party this year. He was surprised when I said no, I have no batteries. He said he thought you needed batteries with a solar powered system. I said no. Batteries have a warranty of 10 years. In 10 years, I’ll be too old to worry about changing out batteries. He was surprised. I tried to explain to him that you don’t need batteries. Here’s why.
You can have a grid tied system without the batteries. You can still cut your electric bill. Depending upon where you live, you don’t need a battery backup system. It is better to use the power company as a battery. During the day when you are producing power and you are not at home (or not using it), it’s going back to your power grid. Then at night when you come home from work and start cooking and using lights, you are buying it back from them. Why not take advantage of that? That’s like money in your pocket. They are the battery. I am using them, the power company, as my battery in the evening hours. The idea is you want to break even. You want to be producing, over a 24 hour period, the same amount as what you are using.
If you decide to install a battery backup for your solar powered system, you do need a certain type of battery. Batteries can have different amp hour ratings. Some batteries have a 20 amp hour rating. I saw a battery the other day that was rated for a 100 amp hour. This battery for 100 amp hours was selling for $300 for 1 battery. It’s a good battery with a 5 year warranty.
How many hours does it take to drain 100 amps? That would be 5 hours at a 20 amp draw but you can’t drain it completely so that would actually be 4 hours. Let’s also say I can’t charge that battery because today was a cloudy and overcast day.
How many batteries do you think that system will need to charge? Let’s figure it out. How many hours are there in 3 days? That’s 24 hours times 3 days equals 72 hours. Divide that 72 hours by 4 hours a day equals 13. So you need 13 batteries at $300 apiece. That’s $3900. Would you pay almost $4000 for batteries? What if you were without sun for 3 days and needed to generate power? After 3 days of autonomy or without sun, you would be dead or without any power unless you had a standby generator to help. You‘ve got to have power coming from someplace. If I generate power from my generator it’s going to cost me more money than the grid. The grid is cheaper than a standby generator.
In emergency situations, some people like having a battery backup system.
Bottom line, grid tie is much cheaper than having batteries. If you really want to get away from the power company completely, then you need to get super-efficient with your house where you use little power. Today, I saw my power usage as 3 amps, but we generated 15 to 18 amps a day. So we are producing more than what we are using. That’s what you need to do. You need to decide if you need to install a battery backup system or use your power company as backup. Who should you use as a backup system?
What’s the best way to convert a small home to provide solar hot water. Or is this not cost effective. We are in AZ FL & TX
Like to have a system tjat provides hot water on demand backed by a hot water heater. Please advise. Are there govt monies for this. Thank You
Instant or on-demand water heaters do not store water. The only way to store is in a storage tank. Tank water heaters use electrical or gas backup. On demand requires instant power needed immediately.
I am not a big fan of on demand water heaters. The jury is still out. Thermal water heaters are energy efficient because it uses sunlight to heat water. It does need storage.
The government does pay you in the form of tax incentives on many energy efficient improvements. For more descriptive information, you can check out their site at http://www.dsireusa.org and just click on your state.
Dear Admin,
Neat Post, The size and weight of any laptop have great impact when it comes to considering using solar energy to power the device. Since most laptops will need about 70 watts of power to operate, any solar panels providing this amount of power would be way too heavy to carry about and use where there is no traditional source for household electric current. But, technology can now come to the rescue increasing the opportunity to meet small mobile applications for energy.
Keep up the good work