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Storage system for domestic solar electricity launched

Posted by Cathy Debenham on 16 October 2012 at 9:48 am

With a large discrepancy between the cost of buying and selling electricity, the owners of domestic solar PV systems are always asking how they can use more of it on site. So it was exciting to speak with the inventors of the first fully integrated storage system for domestic Solar PV at Solar Power UK earlier this month.

SunBat stores electricity when it is produced during the day, and allows homeowners to use it when the sun isn't shining. The makers estimate that it will enable domestic users to meet around 75% or their electrical needs from solar PV.

The system comes in a range of storage capacities from 9.6kWh to 15.8kWh. It has a 6kW inverter which means that it can cope with high demand when running on battery mode. For example, if you have the oven, TV and lights on in the evening, you will still be able to boil a kettle.

The idea is not new. Systems like this have been available in Germany for some time. However, there domestic electricity supply is 3-phase, whereas here it's single phase. SunBat is the first single phase system.

The SunBat will also act as a standby power unit if there is a power cut. This is useful because solar panels automatically shut down when there is a power cut, to ensure the safety of people working on the lines.

The system has an intelligent energy management controller, which lets users control how their stored energy is used, by giving priority to different appliances (for example you could prioritise the immersion). Users can monitor it through a web server. If there is a power cut, these priorities are over-ridden, and the power goes to whatever needs it.

The SunBat comes with a choice of batteries. Standard is a 9.6kW lead-gel battery. This can be discharged to 50%, which means there is up to 4.5kW of energy to use in the evenings. There also is an option to have a more expensive lithium-ion battery. This can be discharged to 70-75% making 6kW of power available for evening use. It also lasts significantly longer. The controller also manages the charging cycles to prolong battery life.

I was interested to hear that in Germany the more expensive lithium-ion battery is fitted as standard, with the cheaper alternative as an option. An interesting illustration of our focus on price in the short term, rather than value over the long term, perhaps.

The SunBat can be fitted to new and existing solar PV installations. As it was only launched at the beginning of the month it's not clear yet what price it will be marketed at. The SunBat stall at Solar Power UK was constantly busy over the three days, and if all the interest turns into demand, the manufacturers hope that they will be able to produce them more economically. Watch this space.

More information about solar electricity from YouGen

How to store your solar generated electricity for use in the evening

Using solar PV to heat your domestic hot water

Solar electricity information page

How easy is it to use renewable energy 'off-grid'?

More blogs on energy storage

Find an installer


If you have a question about anything in the above blog, please ask it in the comments section below.

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5 comments - read them below or add one


michaelmaloneyComment left on: 10 March 2014 at 7:14 am

I think this personally depends on how much is being used in each different household. And of course it's dependant on where the storage unit will actually be distributed. Countries like Australia and in the South East Asian regions where there's lots of sunshine all year round, they could definitely use an energy storage system for the amount of energy they can potentially produce.

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s ward

s wardComment left on: 7 April 2013 at 6:01 pm

how do the solar panels deal with the solar electricty when the batteries are full

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Cathy Debenham

Cathy DebenhamComment left on: 5 November 2012 at 9:18 am

Hi Fabeco, I don't think there's much likelihood of it being financed by Green Deal in the short run - it's certainly not on the initial list - but who knows in the long run. I works in power cuts too, so may be attractive to people living in rural areas that get more of them.

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FABECOComment left on: 3 November 2012 at 2:56 am

An average of 6Kw per day would mean nearly 6Kw for most people to store as they are not home to use it during the day and 6 Kw is more than I would use on an average evening. Yes cost will be an issue but perhaps this could be one aspect of solar pv that could be financed by Green Deal?

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richmcComment left on: 31 October 2012 at 4:19 pm

Fine if you want to add £6000 to £130000 to your PV install costs!

And hopeless in a month that has just passed with an average of 6KWh per day, mostly used so nothing to store.

More snake oil I think.

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