Solar Quote Validation

ForgotRafe

Hi all,

I've got a quote from a local solar company, who have come to the house. I'm very comfortable with them as a company, they're very local and seem very nice. What they say seems to make sense to me and, in general, I like what they propose but I'm far from an expert.

Obviously it'd make sense to get a second opinion, but I'm struggling to find another solar company that has the time. One even told me it could be months before they answer my enquiry!

So is there anyone here that's more knowledgeable than me who would have a look at the quote and see if it looks fair/reasonable? 

Thanks!

Magnitio

If you are happy to post the details on here (removing any personal information), I am sure you will get feedback.

Alnat1

Also good to mention where in the country you are, prices can vary from north to south.

ForgotRafe

Thanks.

Here's an image of the main details. The house has dormer windows in the south facing roof, hence the layout of the panels. We're in Oxfordshire. The price is actually £400 less than that due to a reduction in his purchasing costs (no pressure to buy, the discount applies for as long as he gets it).

We've only just moved in and we're a new household, so estimating usage is hard. Currently using between 7 & 12kWh per day though (lots of improvements to lighting to be made - loads of halogen still!). 

Their approach is not to export but to use/retain as much solar as possible, and use cheap night tariff for the rest. I have an EV. Charger being fitted soon & probably an OHME to take advantage of something like Octopus Intelligent. Then use that to charge car/top-up batteries as required. Effectively running entire house & car off cheap electric and solar. 

norsefox

How often is the car at home during the day?  EVs can both increase and reduce the benefits of a battery system depending on when they are used.

(i.e. if the car is at home often during the day, then a house battery has less value, as the car can effectively soak up the excess generated).

With the SEG from Octopus (15p per kwh?) you might also find that the economics of a battery just don't add up sufficiently over the lifetime of the system.

Officer_Dibble

At a glance that's a lot of battery for the amount of generation. It will mean you're using more of what you're generating and exporting less, but at what price? Compare the payback for 1 battery v 2 batteries (or no battery) using a calculator like this:

https://great-home.co.uk/solar-export-guarantee-seg-calculator/

The price doesn't look hideous to me in the current market and given the difficulty of finding an installer. It's worth getting a quote from Light Renewables in Maidstone if they'll do one as it'll give you a base price. They are willing to travel generally and I don't think I've heard of anyone undercutting them - their initial quote is done over the phone using google maps. They did my installation last March which is working wonderfully and while I had issues with them completing paperwork, their admin seems to have been sorted now.

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

Bianchiintenso

Given the layout and the use of Sunsynk inverter and battery, that  looks very that looks very much like a quote from essential homes via EDF? Unless most companies use similar software for Solar quotes, if it is I’ll happily comment?

ForgotRafe

Bianchiintenso said:

"Unless most companies use similar software for Solar quotes"

I think it's a generic SAAS package. It's a quote from a company called Honest Solar. 

ForgotRafe

Officer_Dibble said:

At a glance that's a lot of battery for the amount of generation. 

Thanks. The battery isn't just for generation, it's so we can store cheap rate electric at night. We can't generate the amount we use each day so it's about getting the rest as cheaply as possible.

ABrass

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 

Officer_Dibble

ForgotRafe said:

Officer_Dibble said:

At a glance that's a lot of battery for the amount of generation. 

Thanks. The battery isn't just for generation, it's so we can store cheap rate electric at night. We can't generate the amount we use each day so it's about getting the rest as cheaply as possible.

Fair enough. If you use the 2nd battery fully for that, that's 4.5kWh (usable, you don't want to fully discharge) a day - assuming 30p/kWh saved using night rates rather than day rates - £1.35 a day, about £500 a year benefit, minus inefficiency of going to the battery and back rather than drawing straight from the grid - nearer £400 a year from the £3k (ish) battery with a 10 year (approx) life. Almost worthwhile. Except you won't need to use it like that on a sunny summer day. The first battery will get you through to mid morning, you can live off what you're generating and there'll be enough in the single battery to get you through until cheap rate starts. That should be at least 200 days of the year I'd have thought. 

It all depends on the future price of electricity of course (though I can't see that assumed 30p/kWh price differential improving any time soon) and I see the appeal of storing as much as you can, but I'm not sure it makes sense financially.