yet another solar quote!

AceMarshMello

Hi all, this is my first post on the MSE forum, so I'd like to say hello all first.
I'm looking to get solar on my roof and have had a couple of quotes, one of which I have discounted as a bit of a rip off (cold call cowboys). The one I am interested seems a better deal, and is from a local installer that I approached. I would be very grateful for any advice you may have.
the details are:
Roof is about 5 degrees off an east/west orientation with no shading on the east slope and a chimney on the west slope.
14x Sunedison 285w panels totalling 3990w.
7 panels on each side of the roof.
Enphase 215 micro inverters to account for the chimney and east/west split.
£6700.
Thanks for your help.

Martyn1981

Hello AMM and welcome.

I reckon that's a good start considering the panels and micro's. Hopefully you can get it a little cheaper.

The chimney on the west side, where is it relative to the panels, is it to their north, or to their south, or in with em?

Have you heard of SolarEdge (SE), it's a similar idea to the micro's but should be cheaper. You still have a device on each panel (but they use a power optimiser (PO) rather than a micro-inverter), then the combined output of all the PO's get sent to a simplified inverter.

I reckon SE have the edge on micro's but only an opinion. Here's a video on how they work:

SolarEdge part1

Do I take it that the rooves can only fit 7 panels each? If not would you consider going bigger, maybe 2.5kWp on each roof?

Mart.

AceMarshMello

Thanks for your reply and advice.
The chimney is on the west facing side of the roof next to the roof edge and in the middle of the north/south axis. Hence it will only cause shading to the western facing side.
I have just watched the Solar Edge video (thanks for posting) and it looks good, makes sense, and I'll speak to our installer for a quote.
Regarding the panels, we do have space to fit more than 7 on each side, but I was under the impression that a 4kw system was the maximum allowed for a private residence?
Lastly, I've done the PVGIS calculation (which doesn't take into account the shading from the chimney) and the figures are below, along with a forecast of our consumption.
Month Generate Consume
Jan 69 556
Feb 122 496
Mar 263 426
Apr 397 354
May 466 336
Jun 473 296
Jul 471 298
Aug 388 304
Sep 292 310
Oct 179 367
Nov 90 430
Dec 55 500

Sterlingtimes

AceMarshMello wrote: »

Enphase 215 micro inverters to account for the chimney and east/west split.
£6700.
Thanks for your help.

My set-up is almost the same. I wonder whether M215 inverter is older stock. I would ask for the M250. You will see my specification in the signature. Paid £6,450 including iBoost. There are pros and cons concerning micro inverters. Mean Time Between Failure figures (they operate with smaller components since they exhibit very little heat generation per unit) are impressive and they accommodate shade well. Ask why you have been quoted the M215 and not the M250.

ed110220

Hi, no you can fit more than 4kW, but you need to get prior permission from the distribution network operator (DNO). They can refuse if they believe it might put unacceptable strain on the local system.

The FIT is slightly lower for more than 4kW (12.57p/kWh rather than 13.88 at the moment). Taken together this means a lot of installers aren't that interested. However given that many of the costs are fixed or mostly fixed (scaffolding, labour etc) the bigger you go the lower the cost per Watt should be (hence the lower FIT!) so it may well make sense.

Also worth considering that the more Watts you fit up there, the higher your self-consumption should be and the bigger the associated savings.

Say you've got a 4 kW system and are producing 1 kW at a particular time. You switch on a 2 kW kettle and import 1 kW from the grid (for simplicity that's the only device you're using!). If you had say a 6 kW system you'd be producing 1.5 kW and only import 500W from the grid.

Ed

Martyn1981

AceMarshMello wrote: »

Thanks for your reply and advice.
The chimney is on the west facing side of the roof next to the roof edge and in the middle of the north/south axis. Hence it will only cause shading to the western facing side.
I have just watched the Solar Edge video (thanks for posting) and it looks good, makes sense, and I'll speak to our installer for a quote.
Regarding the panels, we do have space to fit more than 7 on each side, but I was under the impression that a 4kw system was the maximum allowed for a private residence?
Lastly, I've done the PVGIS calculation (which doesn't take into account the shading from the chimney) and the figures are below, along with a forecast of our consumption.
Month Generate Consume
Jan 69 556
Feb 122 496
Mar 263 426
Apr 397 354
May 466 336
Jun 473 296
Jul 471 298
Aug 388 304
Sep 292 310
Oct 179 367
Nov 90 430
Dec 55 500

Cheers, all interesting stuff.

So sounds like you need some sort of shade mitigation. If you can, try to get some SolarEdge quotes to compare to the micro's. I'd expect SE to be cheaper, but it will depend on the installer. Generally it adds about £40 per panel, but the inverter is a little cheaper, so perhaps £400 more than a regular install. It also has an excellent monitoring system, though you will bore of it eventually.

I've used PVGIS for my WNW system, which has the SE kit. Despite quite a bit of shading I'm still hitting target (much to my surprise) so the kit does appear to do what it says on the tin.

Regarding going over 4kWp. Ed's right, there's a drop in the FiT for the whole system, but if you don't go big now, then you never will, since adding some more panels will be too expensive as you'd have to repeat all the work, scaffolding etc.

Now for the complicated bit. If you can export (theoretically) more than 3.68kW then you need to get prior permission from the DNO (district network operator) before the install. However, for a 3.68kW capped inverter, you notify them afterwards, for their records. So practically all the 4kWp systems going up these days have 3.68kW capped inverters.

Since you have an E/W split system in mind, they won't all be in the sun at the same time, and when the sun is high at noon in the summer it will be hitting all panels at an angle, so it might be ok to fit a 3.68kW inverter. SolarEdge have one, but I suspect this won't be possible with the micro's, as there are special rules (I think) regarding those.

My (basically) E/W system peaks at about 4.2kW in the summer, as I got permission from the DNO to 'go big'. Working backwards from my results, would suggest a 5kWp system for you would top out at around 3.68kW so you wouldn't lose too much to capping, and even if there is some capping, it won't be much.

It's getting more complicated now eh! Fun?;)

Mart.

AceMarshMello

Hi all, I saw the solar installer last night, he got up the ladder and measured the roof up and took into account the chimney Position.
I put your questions to him and he showed us two comparable installs in the local area, one with solar edge, one with Enphase, and the Enphase did produce more. I realise thst there will be other influences behind the data.
regarding the enphase m215 versus the m250, he could supply either, for the same price, but still recommended the m215 as whilst the m250 can handle more power, its more suited to colder brighter climates (Colorado versus Ipswich).
Lastly, we talked about 'going big'. We can fit a maximum of 27 panels on our roof (!), which he quoted trina panels (270w) with enphase m215 inverter at £10k, giving us 270w X 27 = 7.29kw system.
Although sorely tempted, we can't afford £10k, so I then asked what he could do for the same £7k that he quoted us, but using the cheaper trina panels. We were offered 17 trina panels with enphase m215 inverters to give a 4.59kw system, and he would also include and install a solar powered radiator to run off the system, and fit in the living room.
I realise the the 4.59 system will be on a lower fit, but the extra generation should help alleviate some of the shading issue, and also provide more for us to consume.

Martyn1981

All sounds good. Can I check that the 4.59kWp example would run through a 3.68kW capped inverter, to avoid any DNO issues?

[Edit: Sorry that was a really stupid question, forgot about the micro's. So will the installer have to get prior permission from the DNO for the sum of the micro's? That partly why I suggested the SolarEdge system as it all goes back to a single inverter, so a 3.68kW capped unit can be used. M.]

I suspect the next thing for you to do then is work out the various generation estimates, use these to work out income, at the appropriate FiT rates, then divide income by cost and see how they compare.

I don't think the over 4kWp system has to come out on top, but it does have to be within the ballpark to consider.

Any chance you could stretch yourselves another panel or two (still through the 3.68kW inverter). Maybe haggle same price but two more panels?

Mart.

pinnks

Did he mention the cost of DNO approval in the quote - couple of hundred quid from memory

tunnel

pinnks wrote: »

Did he mention the cost of DNO approval in the quote - couple of hundred quid from memory

Think you were robbed, DNO approval cost ne nowt, the installer sent and received a couple of emails and that was it(I know cos he copied me into them). Simples!!

pinnks

Interesting. My lot got an invoice from them which was part of my quoted sum. Different DNOs doing different things, or are they getting stricter - mine was early 2014, indeed system has its birthday tomorrow...