New member, PV quote advice

stevechelt

I am new on here but have been watching for a few weeks now whilst I look into having solar PV installed. I now have 2 quotes and should soon have a third, please let me know what you think of the best quote so far, detailed below.

Semi-detached house in Cheltenham, Gloucestershire, built in 1961 and with a hipped roof. The main roof faces 10 degrees east of south and the smaller hipped section faces 10 degrees south of west. Roof slope 32 degrees. No access issues and almost no shading issues. Any shading would be in the three darkest months early or late in the day from fairly distant trees.

The two quotes I have are very similar in terms of output, both just below 4kwh which as as much as can be fitted. Both are for panels on both the south and west portions of my roof. One seems rather high at £7500 so I have not detailed it. This is my second quote -

3.9 Kwp system.
20 x Solar Technology 195w panels (17% efficient). Roof one - 2.73 kwp, roof two - 1.17 kwp.
1 x Inverter (this is not detailed on the quote, but when discussing with the rep he said it would be an SMA Sunny Boy with dual input, one for each string, matched to the panels output.)
1 x AC isolator
2 x DC isolator
1 x Kwh meter (option for a 'Smart Meter' which will monitor for faults and give access online to current and historical performance. Additional cost of £199 for this, plus £40 per year subscription after first year.)
1 x consumer unit
Total estimated output 3474 kw p/a

Total cost £6000 inc VAT.

10 year warranty, apart from Inverter which is 5 years but has a free 5 year extended warranty from the company, making 10 years. Solar panels have a 25 year limited peak power warranty. Also a 12 month installation guarantee in the event of damage caused during the installation.

This is from a well established local company who have been in the solar PV business quite a few years.

I see many people mentioning the Solar Edge inverters with power optimisers, would one of these make much difference with light winter shading issues and would it be worth the extra cost? I envisage no shading at all throughout all of summer and probably almost all of spring and autumn. In winter there are distant trees that do cause shading (on sunny days) in the first half of the morning and later afternoon to the lower part of the roof. The rep advised me that any loss during the darkest months due to this would not impact overall performance enough to warrant the extra cost.

Many thanks for any comments or advice.

Steve

Martyn1981

Hiya Steve and welcome. Short answer, looks great, I think your detailed post ticks all the boxes.

If your description of the shading is correct (sorry but had to caveat that), then some early/late shading in the bottom months is probably not worth bothering about. Also, as you have a 32d roof, then low winter sun generation from the SE and SW is going to be minimal at those times. SolarEdge is great, but you'd need PO's (power optimisers) on each panel and 20 panels adds up fast.

Do I assume that the 195W panels are smaller than the more common 1m by 1.6m panels? Possibly they are 1m by 1.3m. I have panels of that size on my main ESE roof, as they were a much better fit under and around a Velux. Possibly your hip roof necessitates their use?

Is the consumer unit, a small additional unit, or a replacement/upgrade to your current unit? If the later, then that's quite a package for the price. Well done.

Mart.

Martyn1981

stevechelt wrote: »

Semi-detached house in Cheltenham, Gloucestershire, built in 1961 and with a hipped roof. The main roof faces 10 degrees east of south and the smaller hipped section faces 10 degrees south of west. Roof slope 32 degrees. No access issues and almost no shading issues. Any shading would be in the three darkest months early or late in the day from fairly distant trees.

Total estimated output 3474 kw p/a

Steve

Hello again, just remembered the gen figure. Have quickly slapped the numbers into PVGIS in general location of Cheltenham - see section 5 of the FAQ thread:

https://forums.moneysavingexpert.com/discussion/3872445

only a guesstimate, and no allowance for any shading, but I got:
2.73kWp South (-10deg from south) = 2,560kWh
1.17kWp West (+80deg from south) = 925kWh

total 3,485kWh

Mart.

stevechelt

Hi Mart,

The 195w panels are smaller which does allow more roof coverage than larger panels would because of the hipped roof. I made a fairly accurate plan of the roof and with normal size (1 x 1.6m) panels I could only fit a total of 15 over both roofs, however they were arranged. But with smaller panels some of the dead space near the angled 'hip ridge' can be utilised, bringing it up to near 4kwp.

In the output estimate they have allowed a small degradation due to the partial minor winter shading. Right now at 11.30am on 22 Feb I can see the entire south roof is in full sun (nice day here) and will have been for a few hours, the west roof will be in full sun soon and there will be no shade on either until the last hour or so of the day.

I am not sure what the consumer unit quoted is! I am going to contact them on Monday to arrange a visit to their factory, which they advertise is open for visitors within certain limits of course. I'm compiling a list of questions for When I visit next week and will ask about this consumer unit. We already have a modern unit so I assume it is an additional box of some sort. I'm also going to ask about the mounting system and find out more about the 'smart meter' option and future possible upgrades (immersun type systems etc.)

Cheers,
Steve

ed110220

It sounds as though you've got this pretty well figured out. It can be quite tricky to find the optimum size and wattage of panels to get the maximum system size (or closest to 4 kW) on a roof, if the area is restricted or awkwardly shaped, and still get a good price!

Martyn1981

Hiya Steve, in case you're interested, I've just noticed and posted some info on hipped roof friendly, triangular panels - I kid you not!

Just click on the white chevron:

Martyn1981 wrote: »

Pottering away, as I do, I came across these triangular PV panels. Interesting.

They have triangles, and 'near' squares, designed to work with hipped rooves.

Mart.

stevechelt

Triangular panels, designed to cope with hipped roofs, what a good idea!

So far I think I will stick with that quote. I will also be visiting their factory next week to chase up on some details and I have another quote to get, however the price looks good to me and they seem a well established local company. The rep who came to see me was one of their more senior people I think, he didn't give any sort of hard sell which was good.

I will update later in the week.

Steve

patmanrob

The smart metre option may well be a monitor. GEO solo can be bought for about £100. A sensor sticks on the metre and sends info to a display. If you want to spend £200 on monitoring there's GEO Chorus that also has a sensor for the utility metre so you can also see what you're buying from the grid.


Takes 2 minutes to fit.


Others are available, so shop around.