Any domestic solar PV experts here?

[Martinf]

It seems to me a big expense, how long do you think before you see a profit?

Maybe some just think it’s the right thing to do. We don’t measure the financial return of buying a campervan or taking a holiday!

The real question for me is what is the return on the embodied energy in the system’s manufacturer and installation. Nevertheless, it is generally claimed to be positive and I went ahead and installed a system.

 

[Scruffy]

I've recently had a PV and battery system installed. Hopefully, rough calculations only, I should break even in 4 years, possibly even sooner if gas and electric go up again as predicted in the autumn. But I mainly did it because I felt I should do something to help the environment, in my limited way. Electric car next for my wife, and hopefully EV van in the future when they can do 4-500 miles.

 

[EdH]

I've recently had a PV and battery system installed. Hopefully, rough calculations only, I should break even in 4 years, possibly even sooner if gas and electric go up again as predicted in the autumn. But I mainly did it because I felt I should do something to help the environment, in my limited way. Electric car next for my wife, and hopefully EV van in the future when they can do 4-500 miles.

How long did you wait for your installation?

 

[Scruffy]

It was a long and drawn out experience, probably 2 months from ordering to install and full completion. Pretty much every company is flat out and struggling to get materials, and many had closed their books to new orders. Ask me in a years time if it was worth it, but at the moment ( summer) apart from the standing charges, I would have zero gas and electric bills, and if the FIT was set up in time, I'd be a couple of quid up every day.

 

[Loz]

Have looked into doing a modern solar setup myself, my advice would be to leave the existing "matched" setup as it is and add additional single panels, each with its own micro-inverter that can happily work independently and allow you to increase your generation up to the max you want to go for.

I'm looking at the very popular Enphase IQ series micro-inverters. Using these allows me to fit 6 panels on my shed, four panels on my east roof and four on my west. They can be daisy-chained and connected to a fused spur. There is a central Enphase envoy monitor that allows you to monitor any units installed over powerline communications.

 

[dErZ]

I should probably create a new post about this but does anyone know/understand how to work out the gas to electric equation when looking at the smart meter.

Eg lets say in July I used 211.3 kWh Electric and 458.99 kWh in Gas (just for heating the hotwater tank) , if we were to get an Eddie (immersion heater) what sort of Electric kWh would that be? Im trying to spec battery storage on a PV install.

 

[Salty Spuds]

I should probably create a new post about this but does anyone know/understand how to work out the gas to electric equation when looking at the smart meter.

Eg lets say in July I used 211.3 kWh Electric and 458.99 kWh in Gas (just for heating the hotwater tank) , if we were to get an Eddie (immersion heater) what sort of Electric kWh would that be? Im trying to spec battery storage on a PV install.

Not quite sure what the question is, but this might help:-
We have a 4kw system on the original FIT scheme. We’re about 10 years into the 25yr contract. The first thing I did when we got the panels was to swap our hot water cylinder for a bespoke 300litre Gledhill with 2 x 3kw immersion heaters. I fitted an immersun controller to the immersion heaters. This monitors the amount of electricity we produce & shunts any surplus from the house background load into the immersion heaters. The result is that our net export to the grid is zero, we keep everything we produce “in-house”. Using a fairly simple calculation involving the Specific Heat Capacity of water. It takes around 17kwh of energy (doesn’t matter if it’s gas or electricity) to raise 300 litres of water from 20C to 80C.
The upshot being, that for 6 months of the year, we get a tank full of hot water for free & get paid to do it. We effectively use water to store our surplus solar production rather than expensive batteries.

 

[prog99]

How long did you wait for your installation?

We got panels installed this summer too. Took 6 weeks for the survey to happen (have to admit I was surprised when they phoned me back bang on the 6 weeks to say when would I like it done) and then things moved really fast after that. Was only delayed because we were on holiday for the 1st set of dates.

We had other quotes but they did the survey remotely and then never seemed interested after that.

We used a largish national firm as the local company a few mins down the road were one of the ones who seemed disinterested.

 

[Loz]

Fitted my solar last weekend.
3 on the east pitch and 3 on the west pitch.

 

[Scruffy]

Has anyone fitted optimisers on their panels? I was originally told they weren't worth the extra cash outlay, but now in the winter, I'm getting more shading and feel the two string setup ( east and west facing ) are dragging each other down.

As a side note; has anyone found a decent, active UK solar forum ?

 

[Loz]

Has anyone fitted optimisers on their panels? I was originally told they weren't worth the extra cash outlay, but now in the winter, I'm getting more shading and feel the two string setup ( east and west facing ) are dragging each other down.

As a side note; has anyone found a decent, active UK solar forum ?

Optimisers seem not to be worth it; I went for micro-inverters to cope with small strings and shading. New modern panels are broken down internally into smaller groups of cells with Zenner diodes to stop the blocking.

 

[Martinf]

Has anyone fitted optimisers on their panels? I was originally told they weren't worth the extra cash outlay, but now in the winter, I'm getting more shading and feel the two string setup ( east and west facing ) are dragging each other down.

As a side note; has anyone found a decent, active UK solar forum ?

We have Tigo optimisers fitted to one of our Solar strings (7 panels), which gradually goes into shade in the afternoon, caused by the house next door. Our other string (11 panels) on the main house roof does not have optimisers. The two strings feed a dual input Solis inverter.

I think the optimisers should help give a more graceful degradation to the garage string output. However the output trace suggests they may not be working very well and I’m currently investigating.

Separating the 2 strings is effective and I see no evidence of one causing a degradation of the other.

I did consider dispersed micro inverters, mounted on individual panels. However considering that these electronic components are probably the least reliable part of the installation I was weary from a maintenance perspective of mounting them high up on a sloping roof. It would be fine if they were on A frames on a flat roof, but mine would likely need scaffolding just to look if there were a problem!

 

[RunaboutOZ]

Good day gentleman
If you require some assistance regarding PV solar, I’m an Australian accredited solar system designer and installer contractor.
Due to your limited area to install PV modules, and possible lack of south facing roof areas including shading, I'd go for the micro inverters, as they function independent of each other.
Mix matching PV panels are a no no, if the PV panels are not within 5 % of their power and voltage rating, don’t series / parallel connect them, however using a micro inverter the mix matching of PV panels won’t be affected.

 

[Mick]

Has anyone fitted optimisers on their panels? I was originally told they weren't worth the extra cash outlay, but now in the winter, I'm getting more shading and feel the two string setup ( east and west facing ) are dragging each other down.

As a side note; has anyone found a decent, active UK solar forum ?

Maybe a bit late but my old SunnyBoy packed up in November 2021. I had solar edge & optimisers fitted to my 12 years old array and I can see the increase in output over the last year. It’s easily about 15%.

They do great job feeding my 8.2kWh GivEnergy battery (which had been fitted with the Solar edge) and E Niro EV.

 

[Lukavell]

I'm pleased I found this thread!

I had a salesman round this afternoon who recommended a 6.4 kW system with 2 x 3.3 kw batteries. Around £12k all in. Not bad.

The arrays will be split with 2.4kw facing East, and 4kw, West.

I've worked out my house uses about 17kwh a day, on average. I reckon I'd produce about 21kwh a day, giving me 4 kwh spare, so 6.6 kwh of batteries is too much.

Calculations below:

A 6.4kw system
= 6400 Watts per Hour
× 5.4 (average hours of sun per day)
=34, 560 x 0.77 (derating)
=26, 611 x 0.8 ( E/W facing)
= 21, 289
=21.3 kwh - 17kwh = 4kwh
4kwh spare to charge a 3.3 kW battery.

In theory, I can produce all the electricity I need with a battery to run the house through the night. Break even point would be about 4 years on today's prices.

I have two niggling doubts here about it:

1) Producing all the electricity my house needs seems to good to be true!

2) My Dad has a 4kw system, and battery, with the original FiT, but reckons it's not worth it without FiT, as his bill is the same!? As he's a recently retired Electrical Engineer, I tend to trust his judgement on this, although I can't understand how!

Anyone had similar experiences to my Dad?

Or, want to point out something obvious I've missed?

 

[DXX]

I haven’t looked into depth on the figures but don’t forget that the panels rating is the most they can generate not typical with inefficiencies.
Chargers, inverters, cables, switchgear all have losses.

 

[Pauly]

I doubt you would produce anywhere near that this time of year, in good summer conditions maybe but winter time the averages can be surprisingly low !

 

[Mick]

I'm pleased I found this thread!

I had a salesman round this afternoon who recommended a 6.4 kW system with 2 x 3.3 kw batteries. Around £12k all in. Not bad.

The arrays will be split with 2.4kw facing East, and 4kw, West.

I've worked out my house uses about 17kwh a day, on average. I reckon I'd produce about 21kwh a day, giving me 4 kwh spare, so 6.6 kwh of batteries is too much.

Calculations below:

A 6.4kw system
= 6400 Watts per Hour
× 5.4 (average hours of sun per day)
=34, 560 x 0.77 (derating)
=26, 611 x 0.8 ( E/W facing)
= 21, 289
=21.3 kwh - 17kwh = 4kwh
4kwh spare to charge a 3.3 kW battery.

In theory, I can produce all the electricity I need with a battery to run the house through the night. Break even point would be about 4 years on today's prices.

I have two niggling doubts here about it:

1) Producing all the electricity my house needs seems to good to be true!

2) My Dad has a 4kw system, and battery, with the original FiT, but reckons it's not worth it without FiT, as his bill is the same!? As he's a recently retired Electrical Engineer, I tend to trust his judgement on this, although I can't understand how!

Anyone had similar experiences to my Dad?

Or, want to point out something obvious I've missed?

I have an issue with some of this.

1. That cost is high. I had an 8.2kw battery and Solar edge fitted to my existing 3.2kw array for £5.5k. Panels would have been a further £4k.
2. The DNO will have an issue with a 6.2kw array and you’d need a special certificate for it which takes the provision time out to 6-9 months.. I think 4kw is the max if export is involved for safety reasons on a normal certificate which they may just do over the phone and email. 6kw they’ll be no chance.
3. My payback on the battery alone has dropped from 5 to 3.5 years. 89% of my leccy bill is off peak charging the battery and the car. My most expensive monthly electric bill since I had my battery fitted Nov 21 has been £57 and I have an EV averaging 600-700 miles pm.
3. 6.6kWh is crap especially when connected to a 6.4kw array. Why would he try to sell you that? the solar would fill the batteries in a couple of hours and the rest will go to the grid in May/June/July. 2 batteries in that setup is very inefficient in terms of costs and losses. An 8.2kwh GivEnergy with an AC couple 3kw inverter was between £3200 - £3700 with installation costs on top. Mine came in at £3999.
4. If you are looking at a SEG payment (replaced FITS) then you’ll need a smart meter. That’ll also decrease the payback time.

There are a couple of great sites on FB on this and there are a lot of answers there.

I had 6 quotes and I realised as they came in what a bunch of rip off artists there in this business. There was a disparity of £5k between the top and bottom quotes. Then I spoke to the guy with the lowest quote and the stuff that was missing was legendary. Scaffolding £450, DNO Cert £100 it just went on.

I’d contact Experienced and Professional Electrical and Renewable Energy Contractors ask for Darren Ball. A straight talking very honest guy who stopped me spending fortune with him and gave me a sensible alternative to what i wanted. Use my name I may get a backhander

 

[Mick]

I doubt you would produce anywhere near that this time of year, in good summer conditions maybe but winter time the averages can be surprisingly low !

Spot on. I have 3.2kw array and in May-June I get up to 13kwH a day. Today i got 1.3kwh and all week 7,2kwh. The whole month has been 13,2kwh.

 

[Mick]

Not quite sure what the question is, but this might help:-
We have a 4kw system on the original FIT scheme. We’re about 10 years into the 25yr contract. The first thing I did when we got the panels was to swap our hot water cylinder for a bespoke 300litre Gledhill with 2 x 3kw immersion heaters. I fitted an immersun controller to the immersion heaters. This monitors the amount of electricity we produce & shunts any surplus from the house background load into the immersion heaters. The result is that our net export to the grid is zero, we keep everything we produce “in-house”. Using a fairly simple calculation involving the Specific Heat Capacity of water. It takes around 17kwh of energy (doesn’t matter if it’s gas or electricity) to raise 300 litres of water from 20C to 80C.
The upshot being, that for 6 months of the year, we get a tank full of hot water for free & get paid to do it. We effectively use water to store our surplus solar production rather than expensive batteries.

And that salty is exactly how you do it.