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Hi I’m new to the forum, My name’s John and I live in Gwynedd, North Wales.

My house faces West about 29 degrees NE, if that makes sense.
I’m planning to have a new, slate, roof fitted and figured it would be a good idea to have in roof solar panels fitted at the same time and upgrade the roof insulation, we have no loft.
The panels would be split equally on the roof, 6 on the East and 6 on the West.

As a total newbie to all thing solar I’d like to ask a few questions please.
I’ve had a quote from one company at the moment, waiting on another quote, and they have priced for the following:

Huawei Sun 2000 3.68kW HV hybrid storage inverter L1- DC compatible with 4.02kw system.

4.02kw solar panel system consisting of 12 No. JA Solar 335W including mounting kit and all accessories to grid connection. (The data sheet says the panels have a module efficiency of 19.9%).

Price to supply and install panels and inverter - £5,400

Supply and installation of Pylon US5000 4.8kWh Li-Ion Solar Batteries 48V - £2,400 each

I’d be grateful for any advice on the quality of this kit and if you think the price is reasonable. I winced at the battery price!

The quote says plus 5% VAT but I thought all this work including battery install, at the time of panel installation, would be zero-rated. Also, the roof insulation is quoted at 20% VAT which I understood would also be zero-rated. Any thoughts?

Finally, for now, the panel data sheet says; 12-year product warranty, 25-year linear power output warranty. Any idea what this means, please?


Thanks in anticipation for your time and advise.

Hi John,
Welcome to the forum. With demand being high and area fluctuations I would suggest seeking out a minimum of three quotes. There are companies online who will do a remote survey and quotes. Why not utilise this opportunity as well as local installer quotes?

I pushed my installer and managed to get a 5.12kW system installed and registered. Worth getting the largest amount of panels that you can in one fell swoop.

Having your PV up and on is more important than battery storage. As long as it is a hybrid inverter and batteries can be retrofitted you can easily get along without batts for a while as you learn the it's & outs of PV ownership. A surprising amount of solar pv can be utilised by timeshifting major appliance use to daylight and if you have a hot water storage tank of a decent size a ridiculous amount of solar power can be stored in the water. Look up solar hot water diverter and have a read.

Battery prices are high at the moment due to demand and scarcity. I'd address the aforementioned options first. On vat question, ask each individual installer who quotes for vat details and breakdown of the installation as we'll never know how each company interprets the rules to their own advantage?

I don't think anyone here ever thought 'damn I wish I had less panels'.
kWp(kilowatt panel) is critical as is quality of hybrid inverter as it will be doing the heavy lifting for years. I have JA PV on my second array and they are great. I also have Qcell.and Trina, also excellent. The 10th percent point in panel efficiency isn't that important but making sure you are not paying over the odds per panel is. It's a but like most tech. If you want the bleeding edge it will cost you. P.S 19.9% is a perfectly respectable figure and would gave been envied even just a couple of years ago.

More panels the better has to be the rule because such a large part of the installation is the fixed costs and a few extra panels is small beer. Also you need to future proof for the EV and the world of everything electric.

If you are reroofing have you considered in roof PV which negates the cost of the slates or are they particularly cheap in your area.

Until the recent energy price increases batteries were marginal but now and in the future i think they are essential to maxamise the use of the PV and cheap overnight leccy rates.

My understanding is everything is zero VAT

Thanks guys, that's helpful.
Ken, I am going for in roof to save the cost of slates, and it'll look more aesthetically pleasing. and your understanding is as mine that it should be zero rated.
Joeboy, thanks for the reassurance on the panels, I was only going for batteries at the same time as they will be zero-rated if installed at the same time as the rest of the installation, but VAT of 20% applies if installed retrospectively, but if prices drop it could be worth waiting.

Another couple of follow-on questions if I may:

1) I was told that if I go for more panels I'd have to upgrade to a 3 phase supply as anything over 3.6kW could not be fed into the grid, if I'm not using it, on a single phase supply. Is this not the case? If I am able to have more panels, I will.
2) Should the panels be evenly split between East and West elevations?

Thanks guys

Hi John , i can underline Kens words
If possible fit more Panels , and sure it feels strange too to get new natural slates and cover them up with PV after , Maybe there are alternative ways and cost savings

Supply and installation of Pylon US5000 4.8kWh Li-Ion Solar Batteries 48V - £2,400 each

Is it more than one battery-pack , i hope so , cause 4.8 kWh is not realy a good size in rimes when days get shorter

Billi

Oh was a bit late ...

Sounds to me you are talking to a guy who does not know what he is talking about and suggest you get other quotes.

When i suggested in roof i did not mean ordinary panels sunk into a tray in the roof but roof tiles that are also PV , my fault.

The 3.68kw per phase rule is the limit you can legaly fit panels and tell them afterwards. Usually the 3.68kw is taken as 4kw but if you ask the DNO (the co that owns the equipment eg meter and main fuse) they will frequently allow more. This has nothing to do with no/type of panels just plane and simple what is the max that will be exported. Whilst with a 4kwp E/W system you will not reach the 3.68kw even if you had no leccy loads. To achieve 3.68kw in Wales you would need my guess c5kwp panels.

However if you want more panels then just to make sure you do not breach your permitted export then the inverter is thus set to limit the export. This would not turn out to be problematic until you have a E/W system of perhaps 8kw. In your effort to maximise the no of panels make sure you do not have shading but if you do take the requisite steps to minimise.

The split does not need to be 50/50 and 60/40 should not cause problems, to go further requires calcs to ensure it is all within inverter limits.

East -West Pv also makes the" days longer " and avoid high peaks at lunch time , i would not think that the total production for the same Watt of installed panels per year, will differ much from a strict south facing array , but the benefits for self-consumtion and longer days in a battery supported system are quite significant , as one reduces the time frame the battery per day has to work .

Oversizing a PV array in relation to the single phase export limit is i guess just a matter of a clever system layout ...
But others here know more about that

Thanks guys, that help a lot.

JohnW wrote: ↑Sat Jul 23, 2022 8:00 pm Thanks guys, that help a lot.

Fair to say that we all refine our ideas multiple times. You'll do OK being here. A lot of RE experience hereabouts. Once again, welcome onboard.

Ken wrote: ↑Sat Jul 23, 2022 6:12 pm Sounds to me you are talking to a guy who does not know what he is talking about and suggest you get other quotes.

I would echo this, I have permission to export up to 5KW with my system and I am on single phase. I know there are others on here with much higher allowed export too.

I would have a good read around the forum and perhaps have in mind where you would like to get to so that you can make decisions now that will not limit you later (everything can be sorted but pre-planning is cheaper and faster)

Welcome to the journey