Solar Panels?

Author
Discussion

markiii

3,560 posts

193 months

Friday 20th January 2023
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Richie C said:
NMNeil said:
I agree.
My system powers my whole house, but I'll never recoup my money so for me it's more of a hobby. But with power outages so common here it's nice to have the security of never having the lights go out biggrin
Just waiting for some breakers to set up my latest 15kwh battery bank, which has cost me $2300 to build.
Sounds like this would make a great thread, I'd love to read more about your setup.
me too

geeks

9,119 posts

138 months

Wednesday 1st February 2023
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Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59

cb31

1,135 posts

135 months

Wednesday 1st February 2023
quotequote all
geeks said:
Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59
I'm obviously no expert but 12*400W = 4.8kW, would a 3.6kW inverter be big enough?

geeks

9,119 posts

138 months

Wednesday 1st February 2023
quotequote all
cb31 said:
geeks said:
Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59
I'm obviously no expert but 12*400W = 4.8kW, would a 3.6kW inverter be big enough?
Good question, something I'd not considered. Some Googling required. This is the actual make up of it


OutInTheShed

7,354 posts

25 months

Wednesday 1st February 2023
quotequote all
cb31 said:
I'm obviously no expert but 12*400W = 4.8kW, would a 3.6kW inverter be big enough?
That would depend on the panels being aligned to the sun.
Some people have two strings of panels facing in different directions.

There might be some economics in having more panels and a cheaper inverter, because the number of hours a year a 4.8kW system exceeds 3.6kW may not be huge, and the extra energy at those times may not be particularly valuable.
A 3.6kW inverter is a standard size and may be more efficient when there's less than 3.6kW to be had.
OTOH, an inverter which is running at its max rating more often might be less reliable.

Not so simple as it appears at first sight!

superpp

390 posts

197 months

Wednesday 1st February 2023
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I have a 4.8kw array and a 4kw inverter

My installer sent me this when I asked about inverter size:
https://www.sma-sunny.com/en/7-reasons-why-you-sho...

MaxFromage

1,858 posts

130 months

Wednesday 1st February 2023
quotequote all
OutInTheShed said:
That would depend on the panels being aligned to the sun.
Some people have two strings of panels facing in different directions.

There might be some economics in having more panels and a cheaper inverter, because the number of hours a year a 4.8kW system exceeds 3.6kW may not be huge, and the extra energy at those times may not be particularly valuable.
A 3.6kW inverter is a standard size and may be more efficient when there's less than 3.6kW to be had.
OTOH, an inverter which is running at its max rating more often might be less reliable.

Not so simple as it appears at first sight!
We had a discussion on this thread or similar about inverters. For the small extra cost of increasing the inverter size I really can't see any reason why you wouldn't match it to the system size. Our system is 16.4kW with 1/2 on each side due East/West and will produce a peak of close to 15kW in the summer.

OutInTheShed

7,354 posts

25 months

Wednesday 1st February 2023
quotequote all
geeks said:
Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59
How is the system to be configured?

When your panels can generate 4.8kW, does some of that go into the batteries directly, so there's 3.6kW or less left to go through the inverter?
Or does the power have to go from the panels, through the inverter to the battery system?

You could ask about the merits of having a bigger inverter, or indeed two inverters.

Personally, as our summer daily consumption is often about 7kWh, I would be asking about the cost of a bit more battery.

OutInTheShed

7,354 posts

25 months

Wednesday 1st February 2023
quotequote all
MaxFromage said:
We had a discussion on this thread or similar about inverters. For the small extra cost of increasing the inverter size I really can't see any reason why you wouldn't match it to the system size. Our system is 16.4kW with 1/2 on each side due East/West and will produce a peak of close to 15kW in the summer.
Indeed, brand new panels often produced more than their nominal output, this typically falls off over the years.

Enut

749 posts

72 months

Wednesday 1st February 2023
quotequote all
geeks said:
Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59
I had mine installed in October, 16 panel system (6.2 KWH) with 10 optimisers and 12.8 KW storage (4 batteries), with a 5KWH Solis Inverter. Total cost was £13 K, so whilst not horrendous you should be able to get cheaper IMO.

Evoluzione

10,345 posts

242 months

Wednesday 1st February 2023
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For anyone doing their own, panel costs have dropped dramatically recently. Something like £40 per unit has been wiped off. I'm pondering over buying now and fixing later, but not sure.

Something else of use:
If you can put your panels near vertical they'll favour the low Winter sun, but not the higher Summer sun.
What do we have more of, but less use for in Summer? scratchchinwhistleyes

dmsims

6,449 posts

266 months

Thursday 2nd February 2023
quotequote all
This was 2 years ago on the County council Solar Together scheme (which was about 30% more expensive than going direct to the supplier)



geeks said:
Just had a quote for 12 x 400w panels, 2 x 2.4 kw batteries and a 3.6kw Lux inverter, all installed for £11k, first quote obviously and keen to get a couple more for comparison, thoughts?

Edited by geeks on Wednesday 1st February 16:59

NMNeil

5,860 posts

49 months

Thursday 2nd February 2023
quotequote all
cb31 said:
I'm obviously no expert but 12*400W = 4.8kW, would a 3.6kW inverter be big enough?
It depends on the loads and what the loads are.
An electric motor, such as the compressor in a fridge will draw about 350 watts, depending on size but will have a starting surge current that will draw about 3 or 4 times that. Most inverters will cope with a surge current for a few seconds, but if the fridge, microwave and washing machine decide to all start at the same time the inverter will trip and go into overload.
I ended up using two 3kw inverters in series so they can take any surge current, plus being totally on solar if one inverter starts acting up I can still use the other one, albeit carefully until I get the other one repaired or replaced.
Nothing many things more dangerous than a wife who can't get her morning coffee. biggrin

Pheo

3,324 posts

201 months

Thursday 2nd February 2023
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3.6kw inverters have become quite standard because this is below the g98 fastrack DNO approval level (3.68kw).

Under sizing the inverter can mean the array comes alive more often / earlier in winter as the startup current is lower. So there are some advantages to under sizing it, as the array won’t perform at full power.

Chris Type R

8,018 posts

248 months

Thursday 2nd February 2023
quotequote all
Evoluzione said:
For anyone doing their own, panel costs have dropped dramatically recently. Something like £40 per unit has been wiped off. I'm pondering over buying now and fixing later, but not sure.

Something else of use:
If you can put your panels near vertical they'll favour the low Winter sun, but not the higher Summer sun.
What do we have more of, but less use for in Summer? scratchchinwhistleyes
I'm not seeing price reductions on midsummerwholesale - I'm seeing newer/better spec. panels, but the price for these is increasing. The only cheaper panels seem to be the stock clearance stuff. Where are you seeing price reductions ?

I'm looking at 400W half-cut panels, and these are around £200 ea ex VAT.

Tradesparky has a 15p reduction on Trina panels biggrin - https://www.tradesparky.com/solarsparky/solar-pane...

Edited by Chris Type R on Thursday 2nd February 11:57

Evoluzione

10,345 posts

242 months

Thursday 2nd February 2023
quotequote all
Chris Type R said:
Evoluzione said:
For anyone doing their own, panel costs have dropped dramatically recently. Something like £40 per unit has been wiped off. I'm pondering over buying now and fixing later, but not sure.

Something else of use:
If you can put your panels near vertical they'll favour the low Winter sun, but not the higher Summer sun.
What do we have more of, but less use for in Summer? scratchchinwhistleyes
I'm not seeing price reductions on midsummerwholesale - I'm seeing newer/better spec. panels, but the price for these is increasing. The only cheaper panels seem to be the stock clearance stuff. Where are you seeing price reductions ?

I'm looking at 400W half-cut panels, and these are around £200 ea ex VAT.

Tradesparky has a 15p reduction on Trina panels biggrin - https://www.tradesparky.com/solarsparky/solar-pane...

Edited by Chris Type R on Thursday 2nd February 11:57
Canadiansolar are the ones, available from various outlets. Look for solartradesales, don't be put off by 'Trade' they let anyone purchase once registered.

Chris Type R

8,018 posts

248 months

Thursday 2nd February 2023
quotequote all
Evoluzione said:
Canadiansolar are the ones, available from various outlets. Look for solartradesales, don't be put off by 'Trade' they let anyone purchase once registered.
Thanks thumbup

NMNeil

5,860 posts

49 months

Thursday 2nd February 2023
quotequote all
Don't you have any companies dealing in used panels.
Plenty here in the US.


Chris Type R

8,018 posts

248 months

Thursday 2nd February 2023
quotequote all
NMNeil said:
Don't you have any companies dealing in used panels.
Plenty here in the US.
My view on this is that the panel cost is a relatively small part of the cost of an install - when installing on to a roof, so better to go for something new with greater efficiency, better density and only install once.

Used can be had on ebay, and they'll typically be 200-260W. I suspect there are fewer panels available in the UK due to many installs being covered by FIT agreements.

For example you can get a ex Solar Farm 260W for £70 - which I make 27p/W - extrapolate that to 400W ~ £108. Canadian Solar 410W can be had for £139 new price.

NMNeil

5,860 posts

49 months

Friday 3rd February 2023
quotequote all
Chris Type R said:
NMNeil said:
Don't you have any companies dealing in used panels.
Plenty here in the US.
My view on this is that the panel cost is a relatively small part of the cost of an install - when installing on to a roof, so better to go for something new with greater efficiency, better density and only install once.

Used can be had on ebay, and they'll typically be 200-260W. I suspect there are fewer panels available in the UK due to many installs being covered by FIT agreements.

For example you can get a ex Solar Farm 260W for £70 - which I make 27p/W - extrapolate that to 400W ~ £108. Canadian Solar 410W can be had for £139 new price.
Understood, but I chose my panels on weight and dimensions as I was getting them up a ladder and onto the roof on my own. Even with the relatively smaller and lighter 250 watt panels I used it was still an absolute sod of a job.