Solar PV Quotes

Nick6659

Hi Everybody
This is my first post. I have received three quotes to install Solar PV. The last from Project Solar was eyewatering and will be binned. The other two are from EEC and Forever Green. Once I decided to ignore the battery in the package offered by EEC and made a prorata calculation I was able to compare them with Forever Green. Forever Green so far are the most competitive and offer the following:-
Install a 6 KW system comprising

20 Peimar 300M panels 12 on the west facing aspect and 8on the east facing aspect
20 SolarEdge P300 Power Optimisers
1 SolarEdge 3680 HD Wave inverter

Installation and warranties
Forever Green advised me to delay installing a battery on the basis that they are likely to drop in price and there just may be a government incentive to purchase


I really would appreciate your views on this package please

Nick6659

Sorry, should have added the price £7.75K which seemed OK to me

Martyn1981

Nick6659 wrote: »

Sorry, should have added the price £7.75K which seemed OK to me

Hiya Nick, and welcome to MSE. I don't think that's a bad price, or as you say 'seems OK'. Nicer if it was a bit cheaper, or perhaps the same price but 330Wp panels.

Just some thoughts though:-

Do you understand the 3.68kW rule, and that you need prior permission to export more? Is that why a 3.68kW inverter has been chosen? It's not the end of the world, but you will see a fair amount of capping with that set up. My 5.58kWp E/W can hold 4.2kW for several hours each day in the summer, and 6kWp (or more) would do even better. Have you or the installers discussed contacting the DNO (distribution network operator) for permission for a higher output inverter.

Most inverters can be set to cap at 3,680W, but I suspect from your post that you are specifically being offered the 3680 model, in which case it may be being pushed past it's max of 5,700W DC. In reality 6kWp of E/W panels won't hit that, but it does seem slightly strange and the 4000H model (still capped to 3,680W) might be better. [Note, I'm out of my depth here, and the 3,680 might be fine.]

Just for fun, how much was the Project Solar quote? I'll start the betting off at £12k.

Nick6659

Martin, you are right about Project Solar!!!8217;s quote. In Llantrisant the way

pinnks

Welcome too. I would echo Mart's comments. I have a total of 5.25kWp over two arrays and two inverters. At this time of year I too see well north of 4.5kW and can peak on occasion at 5+kW.

The DNO process is a bit slow but worth pursuing as you could have 5+kW inverter on a 6kWp system and max out efficiency without capping at 3.68kW and also not add much cost as it would only be a slightly increased cost for the inverter.

Good luck

Nick6659

Thanks to both you guys - I!!!8217;ll post again when I have a response on the points you raise in the hope it helps someone else. It!!!8217;s a helluva learning curve!

Nick6659

As promised, here below are comments made by my installer on both the issues raised in the comments above and some of my own. I was particularly concerned about the neeed to increase the inverter capacity based on the 3.68 kW limit when exporting to the grid having seen Martin's comments. I also understand that there is no risk of damage to a smaller inverter in the event of an overload. Therefore, from the comments made, I won't be changing my specification but it certainly has been a useful excercise. I am reproducing the installer's email to me in full but unfortunately, the graphic has not survived the cut and paste process which is a real shame!



"Hi Nick

I like the MSE forum and much of Martin1981!!!8217;s post is good and sound. I worry about the conflict of interest when an installer writes a post on these forums but if you want to quote me on this email, feel free!!!8230;!!!8230;

[G83 is 16A and below and G59 is above 16A. Since we are nominally EU230v the cut-off point is 3.68kW exported to the grid. G83 is a notification, G59 is an application]

This graph may help a little in understanding the production. It!!!8217;s just illustrative and the only certainties are the peaks of the curves and the maximum output of the inverter.

[IMG]imap://nickj%2Ebradshaw%40btinternet%2Ecom@mail.btinternet.com:993/fetch%3EUID%3E/INBOX%3E14773?part=1.5&filename=image006.png[/IMG]
The overriding point here is that this is the best day of the year with no clouds. At other times production is lower. Also consider that the likelihood of actually using much of the power above the inverter line is very low and that it is mostly destined for the grid which lowers its value to you significantly. You might argue that when using a battery the extra power can be stored but even the 13.5 kWH in a TPII is likely to fill up on a day like this from a 3.68 kW inverter plus you won!!!8217;t need it all anyway because of the short nights on such days.

It is very difficult to quantify the financial gain of a larger inverter. Even with favourable assumptions and high usage I can!!!8217;t get the added value much over £25 per year and to be honest I suspect it will be a fair bit less.

A G59 application to the DNO is free but it will take weeks and then there is a connection fee of around £220. There are other potential pitfalls too for example they are within their rights to ask for a witnessing test (at silly money) and once you have applied there is technically nothing to stop them refusing the install outright or asking you to fund an upgrade of the transformer. Add to this the extra cost of the inverter. For example a 6kW SolarEdge is £200+VAT more expensive than the 3.68kW.

Don!!!8217;t get me wrong, Nick, G59 has its place. I do at least one per week and for some people it is beyond doubt their best course of action. There is another option called a G59 Fast Track in which you use a limitation device to moderate export to 16A (3.68kW) but keep full capacity in the house and there is no connection fee. On Wednesday evening I submitted a 6kW G59 Fast Track for your address and on Thursday morning it was accepted and passed. You now have permission for a 6kW system with limitation device (SolarEdge Modbus G100).


It will cost over £400 more to upgrade the inverter and install the limitation device. It is a similar additional cost to the normal G59. Now it is basic economics. My original view is that the upgrade isn!!!8217;t worth it. I still have that view but you are now in a position to freely choose one, the other or neither.

Hope this has helped"


I hope this is of use to others who use this site.



Regards Nick6659

Martyn1981

Nick6659 wrote: »

As promised, here below are comments made by my installer on both the issues raised in the comments above and some of my own.

Hiya Nick, I think that's an excellent response you've got, especially highlighting the cost of the G59 application. I was lucky in that it was free when I did it back in 2012.

I haven't checked the maths for the £25 pa guesstimate, simply because it's very hard to make such a calculation, but mostly because my gut reaction when reading it was 'that sounds about right'. So the installer again has a PV'ers knowledge of the subject, not just an installers, which means a grasp of the reality of PV generation .... in the wild!

The limitation device / G59 fast track comments are extremely interesting. This sounds to me like limiting the export to 3.68kW not the inverter. This is something that I've talked about/mentioned in the past, but I wasn't sure how many domestic scale offerings there were, nor how many DNO's were open to it / had approved devices. The idea is that household consumption can also be covered before the inverter has to cap:

eg, if you have say 200W baseload, and perhaps the dishwasher running at 200W-2000W, then that would reduce export and the inverter only throttles back to prevent export exceeding 3,680W, so it may still be running at 4,000W's, 5,000W's etc.

Damn, it's no good, my inner number geek has to test that £25 figure or I'll get the shakes. So divide it by 6.6p for FiT and export, which gives 379kWh's pa, or about 2kWh's per day in the best 6 months, 4kWh's per day for best six months and really good weather days from 11am to 3pm. Have to agree, that sounds like a max, and probably less.

Zarch

Great reply from the installer..... :beer:

For my own clarity please.

If you install 6kWh of panels, but only a 3.68kWh inverter, which figure is then used for FIT payments?

6kWh, 3.68kWh or both (somehow)?

EricMears

Zarch wrote: »

Great reply from the installer..... :beer:

For my own clarity please.

If you install 6kWh of panels, but only a 3.68kWh inverter, which figure is then used for FIT payments?

6kWh, 3.68kWh or both (somehow)?

Neither. The reading from your total generation meter.

There used to be a reduced rate for having more than 4kWp but I believe that threshold is now 10kWp

Zarch

EricMears wrote: »

Neither. The reading from your total generation meter.

There used to be a reduced rate for having more than 4kWp but I believe that threshold is now 10kWp

Thanks Eric, but super confused now.

Sorry for taking this thread sightly off-topic, but I thought that the current FIT calculation was 100% of size of array x 4p (current generation tariff) + assumed/estimate of 50% of generation x 5p (current export tariff)

So they are derived calculations than actual ones from a generation meter?

Export tariff: your energy supplier will pay you a further rate for each unit you export back to the electricity grid, so you can sell any electricity you generate but don't use yourself. At some stage smart meters will be installed to measure what you export, but until then it is estimated as being 50 per cent (75 per cent for hydro) of the electricity you generate (only systems above 30kWp need to have an export meter fitted, and a domestic system is unlikely to be that big)

http://www.energysavingtrust.org.uk/scotland/grants-loans/renewables/feed-tariffs

Who makes the decision whether the FIT comes of derived 50% figures or mandates the installation of a smart meter?

What is happening right now with current installs?

So for the OP 6kWh system I thought it would be 6000 x 4p (£240) + 3000 x 5p (£150) = £390 per year?

Or could it be 3.68kWh (based on the inverter max)?
3680 x 4p (£147) + 3000 x 5p (£92) = £239 per year?

:huh: