Solar PV System Specification, Components, Quotes & Suppliers

[Phaedrus]

I can get up to 18 panels on the south facing roof of my self-build and I'm looking to finalise my solar pv system specification and pricing.

 

Below is the first quote I've received for supply of a 6kW system in response to my outline specification (i.e. up to 18 panels, all black, in-roof mounted):

 

 

Would appreciate advice on the suitability of the specification and the items included.  Anything in here that I should definitely not use?  Does the pricing look reasonable?  Where else should I be looking to buy the solar pv system from?  TIA

[SteamyTea]

Has your DNO given you permission to connect 6 kW_p to their grid?

[PeterW]

Very keen pricing on that - those all black Trina are not usually less than 30p/W 

 

Is that all available ex Stock too ..?? A lot of panels are back order to China currently. 

[SteamyTea]

Just now, PeterW said:

A lot of panels are back order to China currently

Is that what we used to call 'out of stock' or 'unavailable'?

[PeterW]

2 minutes ago, SteamyTea said:

Is that what we used to call 'out of stock' or 'unavailable'?

 Yep or on their way on a slow boat... 

[SteamyTea]

The Inverter seems cheap.  Nothing wrong with the model chosen.  I cannot find one that cheap on AliExpress.

Is a 1 at the beginning of the price missing?

Edited May 15, 2021 by SteamyTea

[IanR]

Pricing does look very good, would you mind sharing the supplier either here or via PM?

 

It's around £350 - £400 cheaper than I've managed to get quoted for similar.

[Phaedrus]

1 hour ago, SteamyTea said:

Has your DNO given you permission to connect 6 kW_p to their grid?

They have a somewhat annoying approach that they don't want to formally approve pv export before the self-builds are connected.  However, we are paying our share of local transformer upgrade and have received verbal assurance that pv export will not be a problem 

[Conor]

2 hours ago, Phaedrus said:

I can get up to 18 panels on the south facing roof of my self-build and I'm looking to finalise my solar pv system specification and pricing.

 

Below is the first quote I've received for supply of a 6kW system in response to my outline specification (i.e. up to 18 panels, all black, in-roof mounted):

 

 

Would appreciate advice on the suitability of the specification and the items included.  Anything in here that I should definitely not use?  Does the pricing look reasonable?  Where else should I be looking to buy the solar pv system from?  TIA

 

£500 cheaper than what I paid for a very similar setup. Difference with mine was I specced solar edge optimisers and inverter, which adds a few hundred. So I'd say you've a reasonable deal. Just make sure the inverter can be limited to export 3.78kW in case your DNO doesn't authorise anything more. You can still of course make use of peak production by heating water, washing machines etc.

[Phaedrus]

1 hour ago, PeterW said:

Very keen pricing on that - those all black Trina are not usually less than 30p/W 

 

1 hour ago, SteamyTea said:

The Inverter seems cheap.  Nothing wrong with the model chosen.  I cannot find one that cheap on AliExpress.

Is a 1 at the beginning of the price missing?

 

1 hour ago, IanR said:

Pricing does look very good, would you mind sharing the supplier either here or via PM?

 

I'm beginning to get a bit worried that the quote may be too good to be true!

 

Just tried Midsummer Wholesale's pv builder with Longi 360W panels & Growatt 1500 inverter & price is £3507 exc VAT.

 

Perlight, Longi, Q Cells & Trina panels all look to be similar prices.  Panasonic & LG are twice the price.  Any views on which are best technically and/or best value?

 

Also, should I be bothered whether the panels are mono or multi/poly crystaline?

[Conor]

I found midsummer to be more expensive than other places unless you get the trade discount, which I couldn't

 

[PeterW]

Midsummer can be expensive on odd stuff. Wagner are decent but they are all playing the margin game so it’s what you can get someone to be prepared to go to.  If you know what you want and it’s a simple order then cost of sale becomes as much as it costs to stick in it onto a pallet. 

[SteamyTea]

1 hour ago, Phaedrus said:

Also, should I be bothered whether the panels are mono or multi/poly crystaline?

No.

Same with 'thin film'.

 

There is, in practice, not enough performance difference.

Depending on how far the inverter is from the consumer unit, going up a cable size would have a similar performance boost.

[Sandybay]

If you have a 6kw system and you are only aloud to export 3.6kw to the grid, 

What happens on the odd occasion when you are producing 6kw and not using any of that and grid is limited to 3.6?

[SteamyTea]

31 minutes ago, Sandybay said:

If you have a 6kw system and you are only aloud to export 3.6kw to the grid, 

What happens on the odd occasion when you are producing 6kw and not using any of that and grid is limited to 3.6?

Some is turned into thermal energy by the inverter, then the system may go well over limits and shut down.

But I think you still need permission if you can potentially go over the 16A per phase, so the system size is based on module capacity, regardless of what your inverter/diverter does.

Always ask your DNO, there is then no confusion at all and you can make a proper decision.

I once made the decision to ride my motorbike, very drunk, home one night.  Often people get away with this, but that night I didn't.

Luckily it was the 1970s, so a 50 quid fine and a year off the road, and no real affect on my insurance.

Now I would be a social outcast for bring irresponsible, but I was a teenager then. Wish I was now.

Edited May 16, 2021 by SteamyTea

[Phaedrus]

Many thanks for the comments and suggestions.  I'm narrowing in on a final specification for my solar pv system but still have some questions about inverters.  The Enphase microinverters that are suggested to maximize system performance cost more than the solar panels themselves!  My system will be on a roof that is <5deg off due south and shading shouldn't be an issue so am I right in thinking that a two string system to a conventional inverter is the way to go?.

 

Sofar, Growatt & Solis all do suitable 6kW inverters in the £300-400 range.  Fronius & SolarEdge are £800+.  Which inverter would you recommend & why? 

[SteamyTea]

5 hours ago, Phaedrus said:

My system will be on a roof that is <5deg off due south and shading shouldn't be an issue so am I right in thinking that a two string system to a conventional inverter is the way to go

Yes.  No need for anything fancy.

I have always like SMA and Fronius.  Don't get hung up on any live monitoring/remote monitoring, after a year you will not look at that data.  The SMAs had Bluetooth built in anyway, so you can easily download the data locally anyway.