paulc313

PV Panels for me?

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Sorry I know this has been done to death and the same questions have appeared in this forum but I thought I would ask anyway. 

 

I like the idea of PV panels, however after reading through this it appears that many people have said that if quotes are high - 4k - 6k PV it is not worth it financially. 

 

I'm about to do my loan application for renewables, getting an ASHP and potentially PV panels. We were thinking of putting them on our workshop roof which is much bigger than our new build. This is the quote I got:

 

 

 

 image.png.6fde836c78bcb5a10d77ffd8bddc6561.png

 

The workshop is in Aberdeenshire and faces directly south west. There are four of us in total and due to our circumstances it's likely that there will be one of us working from home every day during the week, most probably 2days both of us working from home. So could potentially get dishwasher/washing machine on etc mid day. Plus we will be using laptops/monitors/tv's on during the day as well. 

 

So I was wondering if you could tell me if it is financially worth it? How long will it take roughly to pay the sum back from savings? 

 

Thanks

 

Paul

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8 minutes ago, paulc313 said:

...

So I was wondering if you could tell me if it is financially worth it?

...

 

Is finance the only consideration? Because if it is, the answer is likely to be ... no... But if you take a wider perspective, then the answer may become ... yes. 

And thats the route we took. Yes, emotion comes into the calculation. 

 

Overall, if pay back is the only consideration, then self-building is one of the hardest possible routes to take. Unless you are already in the business.

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My view is you are very unlikely to use all you generate from an 8kW PV system.  Unless you are installing battery storage (another topic for debate) I see little point going beyond 4kW

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@ProDave So we have too many panels and too much electricity being generated?? Even with a south west direction and ASHP?

 

 

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4 minutes ago, paulc313 said:

@ProDave So we have too many panels and too much electricity being generated?? Even with a south west direction and ASHP?

Crudely, you're unlikely to be generating PV at the same time as your thermostat will be calling for heat. Most of the year you're using the grid as a giant battery with a round-trip "efficiency" (ratio import:export costs) of about 30% on one of the better tariffs, more like 0% on one of the Big 6 tariffs.

Views differ on what is worthwhile and isn't - personally I'd be reasonably happy with that system and cost, but I'd also be fine with a payback of >10 years and doing a fair bit of work on load-shifting and time of use tariffs. I certainly wouldn't consider it a good investment from a purely financial point of view however.

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Posted (edited)

First thing to do is run the setup through PV-GIS.

https://re.jrc.ec.europa.eu/pvg_tools/en/#MR

Then compare that to current usage (you can read a meter every hour to get a feel for what is going on.

Battery storage, at the moment, is a nice toy to play with, but probably not worth it.

But storing electrical energy as thermal energy probably is worth it. Especially if you can reduce the capital cost of an ASHP.

There will be times when you over produce, and times when you under produce, but that is just a calculation to find out the overall ideal system and storage size.

 

Look up the prices of DIYing a system. Probably much cheaper.

Edited by SteamyTea

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I have a 4kW system on an E/W split (hopefully to lengthen generation time rather than optimise total output)

 

I manage to self use about 90% of what we generate, by using the big appliances one at a time in the middle of the day (use a timer if you are out) and by dumping surplus to the immersion heater rather than let it export.

 

The small amount we do export is usually when there is no load to use any, and the generation is >3kW so more than the immersion heater can absorb.

 

In the shoulder seasons the ASHP will help use some but for all the summer that won't be heating the house.  I also time the ASHP so it only starts heating the DHW at 11AM when there is plenty of PV generation to use.

 

I assume the quote you had was from an MCS installer?  do you feel confident to install the panels on the roof yourself then just get an electrician to connect them?  That will be a lot cheaper.

 

Even my DIY installed system will have a payback of 6 years based on how much we are self using.

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