Planning solar PV... maybe

oldskoo1

I thought this may be of some help

He has 4kW SE 135 degrees and he is quite local to me and does generate well

http://pvoutput.org/aggregate.jsp?id=7920&sid=6403&v=0&t=m

The interesting thing for me is, his 4kW array is really strong on a "fine" day until 3:30pm at which point it starts to slip a bit. I'm curious to see how yours performs with 2.5kW on SE and 1.5kW on SW, I'm curious because i expect yours to do a bit better having SW panels and so i'm interested to see on average if yours produces a bit more because of this.

oldskoo1

Pulpdiction wrote: »

No didn't ask, they were reluctant to spec anything other than the SMA unless I wanted microinverters - they said SMA is the best as far as they are concerned and they don't go wrong.

Now it sounds like the only thing you need to ask yourself is

- Are you happy with the installer

- Is the price right

Martyn1981

oldskoo1 wrote: »

thats good about the shading. I think it is a fairly straightforward install.

If you want to get the price down did you ask about a cheaper inverter like a Samil SolarRiver 4000TL-D ?

If the SMA price has dropped this may not save you much but i'm curious.

The Samil would probably be about £150 cheaper, and has a 10yr warranty, which is why they are getting very popular, and probably part of the reason for SMA reducing their prices.

But, the SMA has better shade management software, and I'd suspect that would be worth having in this case.

So, unless anything else comes up, I suspect Pulpdiction has found a good package at a very good price ........ so will he jump in and join us?

Mart.

oldskoo1

Agreed

And thanks for the info on shade management. Its a great inverter and greater price! £100 more than what i paid for the Samil so i think Pulp has a fantastic deal.

Pulpdiction

Thanks for the help all, deposit about to be paid

Pulpdiction

Just been out, no sun on the SE facing side now, to be expected I guess, but only a small triangle of shadow on the SW roof, but no where near the ridge, so I think the SW panels will get most of the evening as when the shadow creeps it will go along the bottom, not the top until late on - which is where the panels are.

oldskoo1

Something i learn't which i didn't realise before was that at this time (6:30pm), in summer the sun being lower, travelling through more atmosphere looses quite a bit of power when it hits the panels.

I worried about some minor shading, but at this time right now, it really is fairly insignificant on generation because power is naturally lower. Any effect is fairly minor. I've actually just been outside and my south facing 198 degree array with no shading is currently producing 1,200 - 1,300 watts in perfect sunshine.

I'm not 100% positive on the technical details but if you get 6 panels on the SW string of 1.5kW, you won't be an awful long way behind. Although looking on pvoutput the nearest SW array is putting out 2.2 kWh so that shows you the max potential of sun this time of the day. Remember to factor in losses of 10-14%.

P.S. did you put your details in the PGVIS calculator here : http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe

It should give you expected payback


And as i have nowhere to post this potentially useless but interesting (to me) bit of information, i just took my gas / elec meter readings and realised my electricity meter is not spinning. Knowing i just turned on the fan oven i'm pretty happy my chips are getting cooked for free. Somehow that is a very lean base load!

Pulpdiction

oldskoo1 wrote: »

P.S. did you put your details in the PGVIS calculator here : http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe

It should give you expected payback

I did, but it's all a but too technical for me, I put in my location but I coulnd't work out how to do the 2 roof split or if it could, but it came up as 3570 vs 3351 quoted and which was the basis of my estimate. Based on the price I have it is a 5.7yr payback, so I'm into profit then - hopefully. Either way the money was just going to go into the bank, so I thought this was a better return.

oldskoo1

If you stay at that house it's easily a good move.

I did think about the split roof situation after I posted that. You could always calc it separately. 5.7 year payback is on the optimistic side. Usually 6-7 years is very good.

But with inflation adjusted payments and electricity savings, long term tax free payback is very good indeed.

pinnks

As you have a small amount of shade make sure your installer enables Global Optitrac in the SMA inverter. I only discovered that this year. I have some shading from a chimney while my panels are not in direct sun and then some odd bits of shading from neighbours at various times of day and year.

Turning on Optitrac seems to have made a real difference and it seems to do pretty much what it says on the tin...

If the installer does not enable it you can do it yourself in 5 minutes in Sunny Explorer PC software which is free and uses Bluetooth or LAN to connect to the inverter.