Solar Panel Quote

Essex_Jim

Just been recommended to post here for wider answers from the Energy section

We are looking to get solar panels installed. We drive one EV and looking to purchase a second. Presently averaging 1100 kW electricity usage per month. We are out during the day so there is only 'tick over' electricity usage during working hours.
One initial question. Speaking recently to a retired surveyor, he was negative about panels that are an 'after fit' on a roof sitting above the roof rather than in it. His concerns were bird nests (Have seen a thread about pigeons which I will read), debris building up under the panels and also impacting the 'water tightness' of the roof after been fitted. Anyone have thoughts, comments on this?

On the quotes we have three so far.

Panels quoted were JA Solar and TrinaSolar (370 - 385W)

Inverter Growatt and Solis (5G and Hybrid - may be the same)

Battery Pylon and Growatt. Targeting 6.5kW

Anyone have comments / thoughts / experience on the brands / makes?

Thanks in advance of replies.

Grumpy_chap

QrizB said:

You'll get more replies (and more info) on the "Green and Ethical" bit of this forum, there are a lot of PVers and EVers there.

Some people have problems with pigeons but most don't. Pigeon netting is only a few hundred if it proves necessary, or you can ask the installer to include it in the quote. Roof leaks seem to be uncommon-to-rare.

Those brands and makes are all recognisable! Pylon batteries are well thought of by their owners.

You've not mentioned how big a PV system you're looking at. Systems have grown as panels have got cheaper and more efficient; if I was installing today I'd be able to fit 4kWh in place of my 2.7kWh, and for less than half the price I paid in 2012. Aim for a price of £1/watt for the panels and £500/kWh for the battery. Be aware the battery is unlikely to pay for itself within its lifetime unless there's a serious adjustment to grid electricity prices.

Check out PVGIS to see your likely generation. Here in the central south each kilowatt of panel gives me around 123kWh in June but only 33kWh in December.

OP - I don't (yet) have solar PV, but I am interested exactly what is meant by the comment you made (or passed on):

Essex_Jim said:

a retired surveyor, he was negative about panels that are an 'after fit' on a roof sitting above the roof rather than in it. 

As I understand it most (possibly all) solar system in the UK are retro-fit sitting on / above the roof rather than "in it".  By "in it" I assume you mean like the Tesla Solar Roof, which I understand is not yet available in the UK and I am not aware of an equivalent from alternative manufacturers.  Is that what you referred to, or have I mis-understood?

QrizB

Essex_Jim said:

On the quotes we have three so far.

What were your quotes and the associated system specs, out of interest?

Is your 1100kWh/month pretty uniform throughout the year, or is it biased to the winter (heating) / summer (aircon)? 13000kWh/year could be an all-electric 3-bed semi or the electric half of a dual-fuel bill for a 5-bed des res with pool and hot tub.

Will your electric vehicles be at home during the daytime, and so able to charge while the sun is shining, or will they be away in eg. a workplace car park? A 4kWp solar PV system will generate you 25kWh on a good day. If you've got a thirsty EV you should be able to store most of it, but if you can't use it then once your 6kWh domestic battery is full you'll only earn the SEG export tariff (so 5p or so per kW).

Exiled_Tyke

Thoughts....

1. Yes most installations are 'add-ons'/retro fit. But what's wrong with that?  Ok so not quite as pleasing on the eye but they perform better as they get better airflow keeping the panels cooler.  For the record there's a new(ish) build estate a mile from me which only got planning permission with integral panels.  They look like a poor excuse for climate saving, I'm guessing less than 2kW per house and being integrated won't perform great. 
2. If you want advice here we need specifics: size, location and cost are a good start
3. Don't worry about the pigeons just yet there are far more urgent issues. 
4. Only consider batteries if you want to do the right thing more than get the best financial return. There are plenty here who have them and don't regret paying for them but they are realistic about the financial consequences. 

Hexane

A couple of hundred pounds worth of anti-pigeon mesh completely solves the pigeon/bird problem. I've never heard anyone have problems with "water tightness" caused by solar panels.

370W panels are probably a good price per watt at the moment. Worth paying for more powerful panels (400W are available but still pricey) if you're short of roof space.

I don't believe the brand or make of the panels is particularly important. As for inverter, I and others have Solis inverters and haven't encountered problems with them. (Mine's not a hybrid inverter though).

If you're looking to end up with two EVs then you may want to go for as large and powerful a PV system as you can get.

Solarchaser

Panels mounted on roof afterwards, in my opinion better than mounted in roof.
More airflow means more power on warmer days, can't see how they would compromise the roof integrity as they are fitted using a railing system which sits under the roof tiles. 

Pigeons, yeah they are a problem,  so get pest netting fitted as part of install.

Solar is great, especially if you are at home to use it, but not so much if you are not.

If your high usage is down to EV charging I'd suggest looking at octopus go tarrif for electricity which gives 4 hours of 5p electricity overnight to being down your charging cost. 

My experience with growatt was very poor I'd recommend avoiding their inverters and their batteries.

Pylontech batteries experience has been very positive,  id recommend them personally. 

Reed_Richards

Essex_Jim said:
....We are out during the day so there is only 'tick over' electricity usage during working hours....

This is the worst-case scenario unless one of your EVs stays home whilst you are out.

If not then a 6.5 kWh battery is tiny compared to the batteries in an EV so it will barely put a dent in your EV charging requirement.  You'll quickly fill the battery on a sunny summers day then you'll be relying on timers, home automation and remote controls to try to use some of the spare electricity you will generate.  You can reheat your hot water cylinder and run the washing machine and dishwasher but I think you would be disappointed by how little impact the system had on your overall electricity bills.   

Essex_Jim

Thanks all for the comments. Very helpful.

@Grumpy_chap 'in it' means integrated. my poor terminology. Either incorporated when the roof it first built or renewed. I have been following a person on an EV Forum and FB who is renewing his roof and get the panels incorporated.

@QuirB house is a 5 bed semi three years old. Heating via Gas boiler. The 1100kW  usage is pretty uniform. No AC. EV's are out during the day for work commute. So charge late evening / over night.

@Solarchaser Looking to switch over to Octopus. On a penalty until October with Pure Planet so working to get a Smart Meter (painful!). My Rolec 7kW charger also needs to be 'fixed' to allow timed charges. Will not commutate with the app.

In terms of prices, I have quotes for 8 panels (370 -385W) with inverter and battery ranging from £5800 - £7300. Battery is about £3500 - £4000 of that.

I have an elderly very active relative in the house during the day. Maybe a alternative may be to take less panels, no battery and cover 'tick over' electricity and time washing machine / dish washer / tumble.

Thanks again for all the feedback

Solarchaser

A hybrid inverter (with batteries) will cost roughly double what a normal one will, (from say £500 to now £1000) but that still wouldn't account for the cost jump.
Pylontech batteries work out around £350 /usable kwh, so 6kwh usable (7.2kwh) would be around £2100, so definitely paying too much for that.

You may be able to make good use of the batteries due to your high usage,  but its a long roi for batteries right now, 12-15 years roughly.

The solar won't help you too much during the week, but could charge your EV's at the weekend ready for the week ahead.

Reed_Richards

Solarchaser said:

...The solar won't help you too much during the week, but could charge your EV's at the weekend ready for the week ahead.

That's a good point but if you want to do this perhaps you should try to match the output power from your panels to the maximum input power that the cars will take?

Hexane

8 panels seems a very small number - are you limited by roof space? I'm completely over the top with 23 panels, but to me it always seems that if you're going to the trouble of cost of getting the scaffolding installed for fitting and the electrical work and so on, it's worthwhile getting the maximum generation capacity you can. If it were me and I were roof space limited to that few panels, I would definitely be looking at 400W panels.

Regarding the "in roof" versus "on roof" fitting, in-roof (integrated) panels cost a lot more to install but look a lot nicer; as someone else mentioned, they may also be somewhat less efficient due to less cooling airflow.