Solar Quote Validation

ForgotRafe

ABrass said:

Have you planned your battery size for winter use or summer use? Typically winter electricity use is significantly larger than summer. Which is also when you'd have the least solar generation.

You'll want to make sure you are avoiding as much of the expensive non E7 time slots as possible, which means over buying on batteries for the summer load 

As I mentioned, we've only been in two weeks and it's a totally new living arrangement, so not sure of usage. We're gas boiler and will have LED lighting throughout, so not sure how much different usage will be in summer. I think it really is down to one battery or two. I could buy one and see how we get on, but second one would then be subject to VAT. 

Bianchiintenso

Just so you have a price comparison, we had an 8kWh PV 8kWh inverter (sunsynk) and 10kWh battery (sunsynk) fitted recently total cost £15,500.
We do have an ASHP and charging the battery on E7 gives us from 7:30am till around noon before the grid kicks in on cloud days or 4pm on sunny days. The battery works for us, using between 25-50kWh per day whether the added expense of 2 batteries is worth it to you on your usage is doubtful, In your shoes I would go 1 battery.

yp70479

Or you could ask your installer to quote for a modular battery system  - like Pylontech - that way you could start small and add batteries if you find you need more (although just adding a battery is subject to VAT). I'm not sure if Pylontech is IP65 rated, so it may need to be installed under cover in a loft, garage or outhouse, rather than outside on a wall.

Screwdriva

Hi there! 

I was a bit surprised to see your quote as you have shared a degree of trust and faith in the installer. My thoughts -  I don't have much faith in the quality of the components in the quote. JA Solar 385W is an okay panel but you can do much better. The 5 year warranty on the Sunsynk inverter and batteries are, frankly, a joke.

Here is a comparable quote from my installer or your reference:

10 X Sharp 410W Panels (4.1 kW)
10 X SolarEdge Optimizers 
  1 X SolarEdge 3680 inverter

All with 25 year warranty (worth more than the paper it's written on). < £6K installed.

Battery can always be spec'd if needed but I suspect your usage is lower than needed for a battery to make financial sense (7-12 kWh per day tells me you don't have a heat pump or EV).

It may make more financial sense for you to sell your excess energy via Octopus Agile instead of paying thousands of £ upfront for a battery to store it in. This calculator should highlight this once you input your actual usage. I would instead investing some of that £ in Ripple energy to lower your incoming cost of electricity so that you can achieve an import/ export ratio closer to 1:1 without a battery. 

ForgotRafe

Screwdriva said:

Hi there! 

I was a bit surprised to see your quote as you have shared a degree of trust and faith in the installer

I didn't follow that bit I'm afraid.

Yes, I have an 78kWh EV. No heat pump - gas central heating. 

ForgotRafe

I hadn't included the EV in the daily energy usage as I expected that'd have to be charged using a cheaper overnight tariff. Suspect car usage is an additional 150kWh a week. 

Officer_Dibble

Officer_Dibble said:

As for the specific panels/inverter I've no knowledge of those but I'm sure someone round here will have strong opinions.

I did warn you  I think the suggestion is that any installer that would suggest installing a Chinese brand can't be trusted. Though actually it was Screwdriva's favourite installers (now back in my good books) who suggested my nasty Chinese Growatt inverter which is serving me very well so far. He has a good point on the warranties though - I have very little faith in Growatt sticking to theirs long term. At least Sunsynk don't even pretend to offer anything long term. Well worth trying LR with the spec Screwdriva suggests - they give quotes with and without batteries and operate on a straightforward take it or leave it basis. Just make sure you get all your paperwork from them before paying in full!

pcgtron

I was in the exact same situation as you, with an eV. Lots of people on here who question the payback from batteries, but I had a 4kw system installed with 13kwh batteries for 12.5k back in November. Due to having an eV, I'm on a very good cheap rate tariff. We fill the car and the batteries overnight on the cheap tariff then use the battery power during the day. Our usage excluding the eV was between 11 and 15 kW per day. With the battery, we're hardly ever need to energy from the grid in winter, so most of our electricity is at the cheap rate. 

December is was the first full month of having this system, and it reduced our energy bill by £100. I'm expecting a other winters months to to reduce the by more than this as we weren't home for Christmas and the battery didn't get through the day on a few days if we were cooking a lot. I look forward to summertime where the battery is being charged by the solar rather than the cheap rate electric. 

Whilst the two batteries might not be cost effective, only time will tell with that to be honest, due to inflation, the money was only loosing value, and there's nothing like only paying off peak energy pricing in the winter months. It feels great 

Screwdriva

ForgotRafe said:

I hadn't included the EV in the daily energy usage as I expected that'd have to be charged using a cheaper overnight tariff. Suspect car usage is an additional 150kWh a week. 

If you have an EV, then you'll need to decide if a EV charger like the Zappi is sufficient to charge your occasionally used EV during the day using purely solar. If not, you'll need night time charging via a EV tariff which is when a battery becomes much more viable. That said, I believe the Zappi can charge the EV directly using the EV tariff without the need for a battery, but you'll need to confirm this with them.

You can easily add a quality battery to the spec shared above. My picks are: Tesla > My Energi Libbi > LG > GivEnergy > SolarEdge in order of preference. (The Tesla, & Libbi come with their built in inverters, so if you decide on either, you'll save on the cost of the standalone inverter) 

Officer_Dibble said:

Though actually it was Screwdriva's favourite installers (now back in my good books) who suggested my nasty Chinese Growatt inverter which is serving me very well so far. He has a good point on the warranties though - I have very little faith in Growatt sticking to theirs long term.

PV installers will sell you anything they can if they can earn a profit. Atleast LR offer you quality options, unlike so many in their trade.