How can I store my solar generated electricity to use at night?
Posted by Cathy Debenham on 18 December 2014 at 10:24 am
Q: How can solar power produced in the summer during the day be stored for use at night or in the winter? Converted to hydrogen or stored in batteries?
A: There are a number of options that you can take to use more of your solar generated power. Some are (relatively) cheap and cheerful. Others will be serious investments.
First, the free option. By making a few changes to how you use electricity you can ensure that you maximise your usage while the solar panels are generating. Things that use lots of electricity include the vacuum cleaner, washing machine and dishwasher. Always aim to use them while the sun's out. If you're out at work during the day, you could get timer plugs so that they start up when there's most sun (well not the Hoover, unless you've got one of those clever robot cleaners!).
You could also invest in a monitor that both tells you how much electricity you are using in the house and what you are generating. The one I use displays it in both digits and coloured lights, so I know that when it's shining green we are exporting, and it's a good time to use electricity. When it's red, we're using more than usual (and it might be possible to turn something off).
Next up price wise are switching devices which divert excess electricity generated by your solar panels to your immersion to heat the water in your hot water cylinder. They monitor the amount of electricity generated as well as the amount that your home is using. When there is a surplus this energy is diverted to your immersion instead of being exported to the grid. You can read more about this here.
Inverter manufacturers are now combining storage systems with their inverters. Some are also offering whole house management systems with the inverter. These are interesting options if you haven't yet installed, but very expensive if you have a functioning inverter already. One example was launched this year from SMA & other manufacturers are doing similar things.
However, prices are still high, and unless you're very keen to be self sufficient, self-storage is not cost-effective for most people. Even if it were, not everyone thinks it's a good idea.The Centre for Alternative Technology (CAT) says "the cost of battery storage generally outweighs any savings from storing your own electricity". It also points out that there are environmental reasons not to do it too. Hazardous substances are used in batteries such as lead and acid. Also, if excess renewable energy is fed into the grid then it can replace electricity from fossil fuel power stations, meaning a power station somewhere burns less fossil fuel.
CAT also argues against the use of immersion switches for similar reasons: "In fossil fuel power stations two or three usinits of heat energy from coal or gas are required to produce a unit of electricity. So be feeding a unit of renewable electricity into the grid you replace two or three units of fossil fuel primary energy, whereas by heating water you only replace one unit of heat energy from gas."
Photo: Rob Baxter
More information about Energy Storage on YouGen.
Need help with any Jargon?By Cathy Debenham
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