# If I have a power cut at home will my solar panels just feed my house?



## Mrplodd (Mar 4, 2008)

I was just musing to myself earlier wondering that as I have solar panels on my roof that feed my house, and then feed any surplus into the national Grid, what will happen in the event of a power cut?
Will my panels JUST feed my house (hopefully) or will their output be pushed into (and get lost) in the grid. A curious question I know but I bet someone here knows the answer (hopefully)

Andy


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## Mrplodd (Mar 4, 2008)

Just asked Mr Google (should have done that first really) Seems the inverter needs mains supply to work it’s magic. No mains supply, no inverter converting solar panel output from DC to AC, so if I get a power cut I won’t get any benefit from my panels.
I tried to delete this thread but that doesn’t seem to be possible!

Andy


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## dghr272 (Jun 14, 2012)

As your home solar generates DC an inverter converts it to AC to feed the grid and your home circuit.

If your hit by a power cut your inverter will automatically shut down too, this ensures that self generators don't feed out into the network as engineers could be working on the lines.

Terry


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## TeamRienza (Sep 21, 2010)

A useful post ploddy, I have 4kw of panels on the roof of my home and did wonder about the scenario. Never worried about it as the Motorhome is beside the house, so we can decamp to there.

Thanks Terry for your comments. Makes perfect sense.

Davy


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## raynipper (Aug 4, 2008)

I guess it's like running a generator when you get a power cut. You can't just plug the house into the genny as it would try and feed the whole area. But you can trip all your breakers and only connect to one circuit. But again you don't know when power is restored.

Ray.


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## Pudsey_Bear (Sep 25, 2008)

I would have thought that unless it feeds a battery bank there is no way to take advantage of them, same as in a MoHo, I don't think that having a battery bank for home would be viable unless you set it up to run of that regularly, IE feed the bank and store, nice sunny day feed grid and run off the bank to earn more money, then you need to figure out if it is actually viable financially, which would depend on what you wanted to run, I'd consider anything less than 1000ah too little to do anything much, it'd run a microwave TV and lights for a while, would need to delve deeper, but my brain hasn't woken up yet


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## powerplus (Oct 6, 2014)

hi andy

thanks for asking the question

it is a interesting one and surprisingly i did not know the answer

but have learnt something


barry


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## icer (Dec 11, 2006)

Yes Ray

I wired my genny so that it feeds one separate socket
from that I run my central heating electrics, I have oil fired heating.
Could also use it for other things as well.

Had it two years but never used it

Ian


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## raynipper (Aug 4, 2008)

Yes Ian, we bought the genny after the last big snow storm here took out power for 4 days in 2013. Set up a dedicated extension to the freezers and fridges and never used it yet.

Ray.


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## listerdiesel (Aug 3, 2012)

Andy's unit and what it does really depends on how it was originally configured.

An inverter with battery support will run without mains power, that's the whole point of having an inverter, but if it is configured to only run on solar power without a battery, which is unlikely but possible, then in the event of a mains outage the unit may not operate as its controlling electronics are not powered.

If I was going to have any size of solar array and inverter on my own property, I'd not bother with the grid tie arrangement at all, and just use it for my own purposes, the amount of income that they generate in the UK is not that high and in my view simply not worth the hassle. I'd also have a decent battery bank attached so I could charge during daylight hours and run in the hours of darkness.

Peter


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## Mrplodd (Mar 4, 2008)

Peter

I think you would be surprised at the savings to be made with a solar panel. Don’t forget that I get paid for everything I generate, even if I use it all I STILL get paid for it. 

So I can use everything my solar array generates to power my dishwasher etc effectively for better than free.

I reckon to break even after about 9 years (and that’s just taking into account my FIT payment and ignoring what I save by using the panels output whenever I can) that’s an annual return in the region of 11%

I can see now that if I get a power cut I will be stuffed because the inverter requires mains supply to “work out” how to blend the sine wave of my output with that coming down the grid. I haven’t had a power cut here in years so it was an “Idle curiosity” question.

I have looked at installing a battery bank in order to soak up any excess electricity but the very cheapest is 2.5-3K and as my overall energy bill for the year (gas and ‘leccy) is just under £500 it simply isn’t financially viable (Yet) 

Andy


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## dghr272 (Jun 14, 2012)

Mrplodd said:


> Peter
> 
> I think you would be surprised at the savings to be made with a solar panel. Don't forget that I get paid for everything I generate, even if I use it all I STILL get paid for it.
> 
> ...


Your system reflects the majority of household solar systems I encountered when I worked for our local electricity network company, very few households fitted the battery storage option for the very reason you stated. The syncing to the network wave is critical and the reason why solar fitters have to be registered as competent.

Out of interest Andy who reads your import/export meter, is it your supplier or DNO ?

Terry


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## caulkhead (Jul 25, 2007)

Slightly off topic I know but there was a good programme on the Beeb last June called The Great Village Green Crusade. Actor Robert Llewellyn was looking at ways to try and power his entire village in the Cotswolds with renewable energy. It was a fascinating watch although sadly it doesn't appear to be available now.


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## Mrplodd (Mar 4, 2008)

dghr272 said:


> Out of interest Andy who reads your import/export meter, is it your supplier or DNO ?
> 
> Terry


Every three months I get an email asking me to submit my export meter reading online within 25 days, which I always do on the day the email arrives. Npower who are the people my FIT agreement is with, allegedly send someone every 12 months to carry out a "check" reading, but I have never seen them (but everything is in my external meter cabinet so there is no need for them to bother me)

I know Npower do not have a very good reputation for customer service (I moved from them because they WERE rubbish) but they never fail to pay me within a couple of weeks.

I had smart meters fitted a few weeks ago. It's fascinating to see what each appliance uses!! Even better I can now "fine tune" my usage when the sun is shining in order to use as much as possible from my solar panels without drawing anything from the grid.

Cheapskate, me???

Andy


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## Pudsey_Bear (Sep 25, 2008)

caulkhead said:


> Slightly off topic I know but there was a good programme on the Beeb last June called The Great Village Green Crusade. Actor Robert Llewellyn was looking at ways to try and power his entire village in the Cotswolds with renewable energy. It was a fascinating watch although sadly it doesn't appear to be available now.


He does have youtube channel on green issues, see if it's on there.


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