Solar Panel Guide Discussion

Hemel_Saint

tunnel wrote: »

If you don't want the NE then drop it. You can get higher Wp panels on the other roof to bring your total installed capacity up to 4kWp anyway, with no shading the one roof should come in at around £4k-£5k dependant on materials used.

great advise. I think thats the way to go.

Don't take any sh$t from the sales reps either, come on here and ask and you'll get some excellent advice.
absolutely.... the advise so far has been most useful. thanks all.

If you post your rough location someone will help work out your expected returns

Daventry NN11

plus you may get a recommendation or two for some installers if you're serious

That would be good. bring them on. yes please.
T

Hi Tunnel
Please see my comments in Red.
Thanks

cheers
Mark

pinnks

Those are interesting figures.

My big system is 20 degrees south of west and 3,500Wp. Expected generation 2,790kWh. I have achieved 5-10% more per year so far. I have minor shading issues at extremes of the day. I assume your inverter will be capped at 3,628 on the 4kWp system, otherwise you will need DNO approval for that system which would be a waste of effort to obtain. So, depending on your location (sorry, not looked back if you have said), the projection does not look that bad.

If you do only the SW elevation you will get next to no generation until the panels come into direct sunlight. For my system that is about 11:30 at this time of year. I generate about 200W until 11:30, then by 12:00 I am up at about 3kW. That is why I bit the bullet and put in the second system. 1,750Wp and expected generation about 10% higher per Wp because of the orientation at and expected 1,615kWh per year. Also about 5-10% higher per annum so far. I have major shading from the chimney for about 3 hours a day - annoying but not cost effective to do anything about it now...

If you do both systems, you should get a good spread of usable generation throughout the day. My smaller system 20 degrees east of south, rises quickly to max generation by about 9:30 and the flat-line at max generation until it goes into shadow from my chimney. That means I now get 1kW plus from about 09:00 at this time of year and until about October when the winter generation dip cuts in...

So, the decision seems to be a wish to spend more and get a better spread of usable power (1kW plus for kettle, toaster, microwave and such things), or pay less, get frustrated until late morning but avoid the optic issue on the front of the house. Personally I don't mind the look on the front of our house (big system) and the neighbours don't have any objections either - and believe me they would say...)

Hope this helps.

pinnks

I used eco2solar in Kidderminster for both my systems and would use them again. You are closer to them than I am. My friend near Rugby recommended them to me, so they would go your way. Might be worth an ask... PM me if you do as they might give goodies for recommendations - lol

tunnel

Hemel_Saint wrote: »

Hi Cardew
Yes they did, for both sytems
a) 2 x rooves 6KWP
b) single roof 4KWP

kWh pa................... = a) 4494 ...b) 2996
FIT yr1 4.39........... = a) £198 ...b) £132
Power saving Yr 1... = a) £445 ...b) £297
Export Yr1 4.85....... = a) £87 .....b) £58
Total Benefit Yr1..... = a) £729 ...b) £487

hope the above formatting works!
thanks for your help looking into this for me.

cheers
Mark

Hi Mark,
I'm slightly confused now!
In your OP you stated 14 x 250Wp panels on the SW aspect(3.5kWp) yet your post above states 4kWp. The figure above(2996) would be indicative of a 3.5Kwp system. So which is it, by the way, can you fit 16(1.6m x 1m) panels on your SW roof


Power savings have been massaged a bit too, average savings would be in the region of £120 a year, more with an immersion switch and better again if you work from home and can take advantage of the more sunny spells to use those big appliances.


Just done PVGIS for Daventry and yours is around 3700kWh for a 4kWp system, so again, can you fit them on or can you only get 14 panels(still do-able with 14 x 285Wp panels(3.99kWp))

Hemel_Saint

tunnel wrote: »

Hi Mark,
I'm slightly confused now!
In your OP you stated 14 x 250Wp panels on the SW aspect(3.5kWp) yet your post above states 4kWp. The figure above(2996) would be indicative of a 3.5Kwp system. So which is it, by the way, can you fit 16(1.6m x 1m) panels on your SW roof
.....

Hello Tunnel
Just re-checked all the paperwork.
their covering letter states 24 panels x 250w PV Modules.

however in the internal pages I have just found a section around option 2 (SW Roof only) as using 14x 285w.

So this means if I use option 1 (both roofs) they will use 250w panels for all 24, but if I use just the one roof (option 2) they will use 14x 285w panels producing 3.99KWP

is this something to be concerned about if its 250w or 285w?

thanks again for coping with the daft questions.
cheers
Mark

tunnel

Hemel_Saint wrote: »

is this something to be concerned about if its 250w or 285w?

thanks again for coping with the daft questions.
cheers
Mark

It's not a daft question and it's certainly nothing to be concerned about. You can get panels up to 330Wp, 285's are pretty common


Their paperwork for a 3.99kWp system is incorrect though, in fact the figure 2996 is under PVGIS's estimate of 3110kWh for a 3.5kWp system for NN11
The company that quoted you don't fill me with confidence to say the least


Edit, my mistake, a 4kWp system would make 3550kWh per year, I put in the wrong azimuth at 30 deg rather than 45 for SW(my bad)

Martyn1981

Hemel_Saint wrote: »

Hi Tunnel
Please see my comments in Red.

great advise. I think thats the way to go.

Thanks

cheers
Mark

Hiya Mark.

I think Exiled Tyke and pinnks have laid out the arguments for and against the NE system.

My thoughts:
It's good to have a mix of generation.
You can't extend anymore under FiTs, so go big at the start, or not at all.
Adding more panels, costs proportionately less as there are a lot of overheads in a PV system, so more panels don't cost that much more.
Bigger system allows for more water heating or batteries in the future - but won't generate much in winter, and in the summer you'll have plenty of spare from the SW.
But NE is pushing the limits, and as mentioned before, 45d pitch does more damage to the generation figure.
No need to worry about the DNO or larger inverters or capping if you just go with the SW.
4kWp SW is a great system.

NE 45d pitch not good, but you will having a nagging doubt in the future. It's your decision, but personally I don't think you can go wrong, I'm split 50:50, either decision is perfectly fine.

Just to confuse you further, if there's room on the SW for a few more panels, then slap as much up as you can, with a 3.68kW inverter, that's an excellent compromise.

BTW, I also had a play with PVGIS, and got exactly the same as T with 3,550kWh pa. That site is very good, gives excellent guestimates, so income would be approx:
FiT 4.32p x 3,550 = £153
Export (50%) 4.91p x 1,775 = £87
Leccy savings approx £120
Total = £360

Oil savings from diverter are on top, but almost a separate calculation on the extra kit.

Against £360, you really need to get the cost down under £5k and aim for £4k. Some folk on here paid £4.5k a year ago.

Mart.

Hemel_Saint

Martyn1981 wrote: »

Hiya Mark.

I think Exiled Tyke and pinnks have laid out the arguments for and against the NE system.

My thoughts:
..... I'm split 50:50, either decision is perfectly fine.

Thanks for all the guidance. think I will go SW only as my wife wants to keep the kerb-appeal clear.

Just to confuse you further, if there's room on the SW for a few more panels, then slap as much up as you can, with a 3.68kW inverter, that's an excellent compromise.

BTW, I also had a play with PVGIS, and got exactly the same as T with 3,550kWh pa. That site is very good, gives excellent guestimates, so income would be approx:
FiT 4.32p x 3,550 = £153
Export (50%) 4.91p x 1,775 = £87
Leccy savings approx £120
Total = £360

Oil savings from diverter are on top, but almost a separate calculation on the extra kit.

Against £360, you really need to get the cost down under £5k and aim for £4k. Some folk on here paid £4.5k a year ago.

Mart.

Cheers Martyn
Great summary.

Can I just ask you guys if you can clarify what I should be asking the next installers to quote for, if I go SW only...

• As many panels as poss on SW roof (250w or 285w)
• a single 3.68kW inverter
• An Immersion Throttle/Converter (ie Apollo GEM/I Boost)
• OWL monitor
• no to a Voltage Optimiser

all for under £5k.
Is that realistic?

sorry to hog the board, but this advice is fantastic and hopefully a help to others too (that’s my excuse to keep asking loads of Qs on here!!!)

cheers all
Mark

tunnel

Hemel_Saint wrote: »

Cheers Martyn
Great summary.

Can I just ask you guys if you can clarify what I should be asking the next installers to quote for, if I go SW only...

• As many panels as poss on SW roof (250w or 285w)
• a single 3.68kW inverter
• An Immersion Throttle/Converter (ie Apollo GEM/I Boost)
• OWL monitor
• no to a Voltage Optimiser

all for under £5k.
Is that realistic?

sorry to hog the board, but this advice is fantastic and hopefully a help to others too (that’s my excuse to keep asking loads of Qs on here!!!)

cheers all
Mark

Hi Mark
You can put as many panels on your roof as you want. The problem is that if you go over 3.68kW export you need DNO approval.
You could however put a 5Kwp system up there and throttle the output using a 3,68kW inverter but I don't see the sense in that. It shouldn't cost much if anything to get DNO approval, and having that approval takes away the need to throttle the output


And yes, you should easily be able to get all of the above(4kWp system) for under £5k


So how many panels do you reckon you could get up there(SW)?

Hemel_Saint

tunnel wrote: »

Hi Mark
....
So how many panels do you reckon you could get up there(SW)?

From the plans from the 1st quote.
29.6 ft wide
15ft deep
with a chimney fairly central.

they had 14x 285w around the Chimney stack.
If they use all space, 16 maybe 17.

cheers
Mark