Generic solar query

Stubbsy11

Hi all

I wondered whether it's possible (and cheaper?) to source panels/batteries/inverter myself, or if it makes more sense to go through a company.

I only ask as I'm finding it hard to actually get a quote back from a company, and also figure if I can do it myself then it will cut out the middle man who will add their margin on top (although not sure whether their trade prices may make the whole thing cheaper).

Would appreciate insight into this.

Failing this, I'd be grateful if someone could recommend what spec I should go for (model/wattage of panel, battery type etc) so I can know at least what I'm looking for when I do eventually get quotes back.

Appreciate any help on this - thanks in advance.

Bab

Screwdriva

Hi there! 

May I ask where you are located?

Most installers now quote for low end component brands at high end prices. Sadly, this practice is getting worse!

A quality 400W panel (Sharp, Hyundai, Solarwatt, Sunpower, REC, Panasonic, Aleo) will cost from £250. 
A quality Inverter ( GivEnergy, SolarEdge or Enphase) will cost from £1300 upwards with 20+ year warranty.
A quality optimizer (SolarEdge or Tigo) will cost from £50 each. 
A quality battery (GivEnergy, SolarEdge, Tesla or LG) start at £3300 and rise dramatically. 

Bird netting, scaffolding and transportation are always optional extras. For a quality 4kWh system (any mix of the above brands), without a battery, you shouldn't be paying a penny over £6K installed in this market. If your installer deviates from these brands or the prices are dramatically higher, I'd suggest walking away. With a bit of patience and luck, you can & will do better. 

Stubbsy11

Hi Screwdriva

Thanks for the advice, much appreciate!

I'm located in South Wales. The only quote I've actually received back so far is for £17.4k which includes;

20 x JA Solar 370W Mono Percium Half Cell Panels
2 x 5kwh Puredrice AC coupled batteries
1 x 3.5kw Solar Edge inverter

This seems incredibly steep to me - not that I'm going to go with the company, the quote they put together was so amateur (screenshots of the products from different websites, cut-off screenshot of the quotation itself). However, this is the only quote I've had back so far.

Do you know if I'd be able to source the equipment you posted myself? I guess I could then find a local installer to carry out the works and avoid paying a premium for the product itself.

Thanks again!

Bab

ABrass

If you buy the bits separately then you'd have to pay 20% VAT on it. If it's installed for you then it'll probably be VAT free. Plus your local installer won't be that interested. Some people do it but it's a very niche activity.

The quote is indeed awful. For a start it'll probably blow up the inverter if your panels tried to push 7.4 kW through a 3.5kW inverter.

Stubbsy11

Aaah ok that makes sense, thanks ABrass!

So as I understand it, the inverter has to be able to handle the output of all the panels (so should be equal to or higher than the array output?), but the battery being around half the output of the arrays sounds about right?

Thanks

ABrass

Not quite, the opposite is more normal. It's very common to have more panels than your inverter can handle. I have 8kW of panels and a 6kW inverter.

Some do it because they have a limit on their export from the DNO (not common anymore as there are alternatives now).

Others have split arrays so the panels will never all be working at full power at the same time, I fall into that category.

Some do it because panels are cheap and nealr all the time they won't be performing at 100%, so under normal circumstances you get more usable power. Plus inverters are slightly more efficient when they are smaller.

ABrass

As for batteries, there's a range of approaches.

Big batteries mean you can last most of a day or more on the power they hold. They don't make sense financially for most people but they are cool. If you have Economy 7, or Octopus Go then you may be able to charge them on cheap overnight power, then use Solar to top up during the day and never buy peak rate power.

Small batteries will not last the night, or might just on a good day. They get charged and discharged daily and will probably pay for themselves.

More panels is a better financial investment than batteries and a smaller array. Some people think, very strongly, that batteries are a bad idea and shouldn't be touched.

Don't forget this is a forum and this is all just a random person on the internets opinion.

Alnat1

People who do have batteries tend to really like them. It's a great feeling to draw almost nothing from the grid for around 7 months of the year. My average was 0.5kWh a day Mar-Sep, usually made up of lots of little "leaks" of a few watts when appliances get switched on and the inverter takes a few seconds to respond. Now there's less generation, the battery can get topped up when Octopus Agile has cheap slots.

Have a look at this great-home.co.uk/solar-export-guarantee-seg-calculator/ and you can try out a few possibilities and get an idea of ROI.

70sbudgie

The issue with installing yourself is that you need an MSC approved installer to get a SEG (export) tariff.