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Battery Backup/storage off PV Array

madswitcher
Grafter
Posts: 257
Thanks: 2
Registered: ‎01-08-2007

Battery Backup/storage off PV Array

Hi Folks

has anyone had a battery back up/electricity store added to their PV solar array?  I am toying with the idea, but it appears to be  limited in what it provides when the mains fails.  For example, it can only run one circuit when the mains fail, or you can have a dedicated circuit that only runs off the BBU, and that only comes on when the mains drop out.

I would be interested in the views of anyone that has had one installed and how they got on with it.

Cheers

Mike

3 REPLIES
Baldrick1
Aspiring Hero
Posts: 2,001
Thanks: 848
Fixes: 67
Registered: ‎30-06-2016

Re: Battery Backup/storage off PV Array

I have a PV system and looked into it some time ago. We obviously have different ideas as to the purpose.

My understanding is that they are used to store electricity generated in excess of your usage during the day to use when the sun goes down or when the household demand exceeds that generated, hence using as much of the PV energy yourself rather than exporting it for peanuts then paying full price for imported power during high peak usage periods or the evening. We have very few power cuts so the expense just for this purpose would not be justified, I have no idea if they have this UPS capability without the incoming supply being isolated.

When I Investigated installing a battery system I looked at the cost of the installation, ongoing maintenance and the lifetime of the batteries. My conclusion was that at present it is not a viable option for me.

In my case I divert as much excess generated electricity as I can to my immersion heater. During the summer I still export some electricity, my next move will be to fit a destratifying pump to the hot water tank so that the whole tank gets up to 65 degrees C rather than just the top. I have a friend who has done this who tells me that this provides enough hot water for two days.. For at least 6 months of the year I export nothing and save on water heating. During the summer I have all my hot water most of the time for free.  

 

Marksfish
Aspiring Pro
Posts: 471
Thanks: 35
Fixes: 3
Registered: ‎22-11-2014

Re: Battery Backup/storage off PV Array

It's something I have considered, but it doesn't seem to be cost effective, with the batteries costing almost as much as the panels. The most we generate on a sunny summer day is around 20kwh. We use 16kwh on a average day throughout the year, so not sure if there is any real benefit to the system for us (we have a 3kw system).

Mark

madswitcher
Grafter
Posts: 257
Thanks: 2
Registered: ‎01-08-2007

Re: Battery Backup/storage off PV Array

Hi again,

Thanks for the replies: they are in line with my present thoughts in terms of cost effectiveness and limits on what you can do with the power once you've stored it.

We also use a diverter to use up excess power to the immersion heater to save money on the gas bill, so I think we will stick to that for a while until the cost of energy storeage comes down. Let's hope Teresa May's promise of greater UK reserach into batteries bears fruit.

Cheers

Mike