Solar panels and battery - any real world reccomendations?

DRZ said:
So the OcUK wisdom would be to up the inverter to ~8kW and pack as many extra panels as I can on the NW side of the roof? I'll see what the installers think - I know the DNO application paperwork has gone in already so they might not be too keen to change things at this stage but it is worth an ask.
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I'd say so.

Also don't worry about the ROI too much either as we just don't know what the export tariffs or import tariffs are likely to be. Do it for the fact that for 70% of the year with a system of that size you can almost be self sufficient. In summer NW panels do help a lot.
 
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Right, £2340 to add on an additional 11 panels (150*, 40* incline) and increase the inverter size. That brings the cost down to £1325/kWp...

They predict an increase in production of ~2350kWh annually which seems conservative vs the numbers Ron-ski is expecting from his 12, but that's OK. They have raised the likelihood that my DNO will want to cap my export, which may add slightly to the cost (they have a recent install of the same size with an additional DNO cost of several hundred quid for witnessing etc) but while irritating it isn't the end of the world...

I think this extra is a no-brainer, glad I asked here - thanks! :)
 
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My 4.62kW of NW facing panels (137 degrees and 35 degree tilt) have beat the PVGIS prediction in every month since I got them installed in January aswell. Since installation from 10th January to the end of May, they should have produced 976kWh but have actually managed 1135kWh. That's on an annual prediction of 2794kWh and the weather has not been great either.

You're doing the right thing getting them put in at the same time. I didn't do this as I was told by pretty much everyone it wouldn't be worth it so ended up paying more when I finally got it done.
 
Ron-ski said:
Mine are at 120 degrees, so less north than yours.

No idea where you are in the country, but for roughly around Derby PVGIS reckons around 2850 kWh.

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission

Photovoltaic Geographical Information System (PVGIS)
re.jrc.ec.europa.eu re.jrc.ec.europa.eu
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Wirral, between Chester and Liverpool basically, at the top of a tall hill.

reef said:
My 4.62kW of NW facing panels (137 degrees and 35 degree tilt) have beat the PVGIS prediction in every month since I got them installed in January aswell. Since installation from 10th January to the end of May, they should have produced 976kWh but have actually managed 1135kWh. That's on an annual prediction of 2794kWh and the weather has not been great either.

You're doing the right thing getting them put in at the same time. I didn't do this as I was told by pretty much everyone it wouldn't be worth it so ended up paying more when I finally got it done.
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This was my experience with literally every single installer I contacted. They all suggest it just is not worth it, you'll never get the return on it etc etc but yet the numbers suggest I will definitely benefit from these 11 panels. I wonder why? It can't be just an attitude of "South-facing good, North-facing bad" can it? Perhaps there's a perception that if they do size systems like this people just get upset at the outright cost when compared with someone else doing South-only quotes and they just keep it simple to compete?

Ah well, I'll take my newly-sized 12.76kW 8872kWh/yr SE/NW system and see if it does work out the way the thread suggests!

Just waiting on DNO approval now, hopefully get it installed while there's still some summer left!
 
It’s definitely a perception thing and working off old rule of thumbs which don’t account for better panel technology. Installers are still peddling cookie cutter 4kw systems they can fit without approval rather than considering current and future demand (EVs and heat pumps) on what is a 25+ year investment.

It wasn’t that many years ago when sub 300w panels were still a thing and NW panels wouldn’t have been worth it. Newer panels are so much better with low light.
 
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DRZ said:
I think this extra is a no-brainer, glad I asked here - thanks! :)
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Sadly too few people ask for advice from a group of people with many decades of combined data and experience. The key thing is we aren't after your money, or making an effort to profit from you, mostly the opposite, so the advice may be counter to the 'professionals' but they will be following guidance from MCS etc. and recommendations that are no longer optimal given how cheap solar PV now is.
 
Something I will need to tackle in time is to work out how to dump excess solar power into my hot water tank once the batteries are full. I have a vented cylinder at present, the contents of which are gas-heated by a system boiler which has some automated valves to switch between the hot water and the central heating as required. As far as I can see, there is no provision to heat this water using electricity. I'm not sure I can stand the thought of replacing things right now if its not a really simple fix, nor is it at all appealing to run a supply to where the tank is from the CU due to an absolutely moronic lack of future planning by both the previous owners and the electricians who re-wired the place in the mid-2000s.
 
I had an iBoost and i've now an Eddi. However, as has been said above, I now fully charge my car, batteries and water overnight @ 7.5p to maximise the amount of solar I can export @ 15p.
 
I wouldn’t bother with heating the tank on solar. The initial cost vs gas use/export at present shows it’s certainly not worth it. Perhaps in the future if export changes which I doubt.

I bought an expensive EV charger in order to divert my solar, pointless however when it’s 50% the cost overnight when exporting in the day.
 
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