Solar Panels.

[John]

I've seen a few adverts recently when browsing the web advertising Solar Panels.

I normally ignore such adverts but it made me wonder whether they are viable these days as I imagine the cost has dropped over time.

I presume it is a question of how long we intend to stay in the property until we break even... we probably spend £50 a month on average on electricity.

A quick search reveals we're looking at £5.5K > £6K for typical 3 bedroom house (although not sure if that include storage batteries) so we're talking 10 years to break even not including selling back to the grid... which I imagine attracts a pittance in return.

Are there any other considerations though like do they need to wire them in to where the meter is and mains comes into the property or can it be joined anywhere (i.e. do big cables need to be run across the house)?

 

[Deleted member 37751]

For solar to be viable you need storage.

In fact, in your case, I’d go for storage first (2kw should be about £1-1,500) and get a tariff that allows you to “download” energy through the night cheap and then discharge when you need it.

 

[Teego]

For me, 10 year payback isn't attractive and newer generating and storage technology is coming on stream. What about low cost storage cells to hold your off-peak electricity from the grid? You could probably take yout batteries with you when you move.

My grandfather had a very large village house. It had running water but no mains electricity. In an outhouse he had a petrol generator charging rows of 12v car batteries. He had 24/7 electicity in the house at the flick of a switch, just like everybody else. When the batteries ran down the genny would automatically kick in. It wouldn't take too much brain power to develop a modern version.

 

[merc07]

Mine are installed on an out house, no need to wire them straight to the meter.
We did have to have the cable upgraded though as it was originally only meant for light use.

Pay back depends how much of the free electric you can use - or store and use at night although I got mine last year so still get some income from pay back.

My 3.6kw system (11 panels) gives me around 3kw peak in the summer and I use almost all of it. A 1kw pump and 2.1kw heater are switched remotely when my app shows enough power and nothing else is on.

In the winter I have a couple of oil heaters that I switch the same way..

You have to learn to use things one at a time and only put the dishwasher on when the sun's out - this takes longer for some !

Batteries are expensive but just a 4kw system would allow me to run free during the evening too..

 

[zipdip]

Well solar energy is no longer viable as they have cut the rates down so much ,I had solar panels fitted to my last house,I paid 8 grand for the panels plus I has solar boost fitted which when you were not using the electricity you were making diverted the power that should be going to the grid to power the immersion heater in the hot water tank, in the 4 years I stayed in that house I got between £800 and £900 a year back for having the panels ,my son fitted then early to his place he gets 47P a unit at a cost of £12 grand and he has had them for ten years,I suspect he has got his money back by now,the last figures I saw you now get 5 1/2 p a unit,it is just not worth doing anymore.

 

[merc07]

Yes, mine is about 8p payback total per unit, but, I save alot on the actual electricity.
My monthly average is down to £35
That includes In the summer:
1kw pump X 8hr
2.1kw heater x4hr max
Total 16.4kw/day, 492kw/month would cost me £73.80 max on top of the normal electric use.
In 1.5 years since fitted, they produced 6.6mw, about £1000 worth + £500 of feed in tariff @8p

If you use it, then it is worth it but most people won't use anywhere near the amount generated at any one time.

Batteries are what you need but they are still crazy money.

 

[BTB 500]

I think there's more focus on power efficiency with household appliances etc. these days, and things like LED bulbs make a fair difference. Over the last 6/7 years our electricity usage has dropped slowly from over 3,500 kWh per annum to under 2,700 for 2019 (1980s 4-bed detached), so big capital expenditure on solar panels would make even less sense now.

 

[Deleted member 113659]

I've seen a few adverts recently when browsing the web advertising Solar Panels.

I normally ignore such adverts but it made me wonder whether they are viable these days as I imagine the cost has dropped over time.

I presume it is a question of how long we intend to stay in the property until we break even... we probably spend £50 a month on average on electricity.

A quick search reveals we're looking at £5.5K > £6K for typical 3 bedroom house (although not sure if that include storage batteries) so we're talking 10 years to break even not including selling back to the grid... which I imagine attracts a pittance in return.

Are there any other considerations though like do they need to wire them in to where the meter is and mains comes into the property or can it be joined anywhere (i.e. do big cables need to be run across the house)?

I bought a full kit at £2,700.00 and installed it all myself (bungalow and tiled roof so very straight forward.) Slate roofs are a pest to fit brackets though.

Whrn my sparky mate commissioned the system the FIT was £0.14ppu.
Get get on average of £550.00 per annum back so not great. I’d have been disappointed had I paid £8-10k for the whole thing but given we didn’t it’s kinda made it ok ish.

No heavy complicated wiring John. All panels are linked together and then into the inverter. Then a 2.5mm T&E to isolator switch next to FIT meter & consumer unit. Very straight forward.

Text/PM me if you need any more info matey

 

[Deleted upon users own request member 138506]

John, These are my returns on panels installed on a 4-bed in 2012 at a cost of £4750. To date I have received payments of £4941.09 but take into account your own electricity usage savings bring total to £7817.03

 

[merc07]

This should give you an idea of what you can expect to get from a 3.5kw system.
We had them fitted in March 19, hence no data before.
South facing but on a low pitch roof, probably about 12 degrees so not ideal. 11 X 330watt panels each fitted with micro inverters to prevent shade issues from a near by Apple tree. Cost was about 5k -

Installing now, as others have said, with no tariff, you would need to use everything you generate and hope the sun stays out for 8 years !

 

[BTB 500]

This should give you an idea of what you can expect to get from a 3.5kw system.

Interesting that it rarely goes above 500 kWh a month in the summer ... if you assume 12 hours of daylight and 30 days a month that equates to about 1.4 kW. Is this normal, or down to the installation being less than ideal? How often to the panels need cleaning?

 

[merc07]

Low sun, cloudy days Oct - Feb.
Summer months is 18 - 24kw per day which is when I actually need to use it most.
In the 18 months so far, it is 6.6mwh / 6600kwh

Don't forget it ramps up and down during the day - you have to be careful using appliances to get the most from it.

This is June Vs last Friday...the sun is getting lower now..
Believe it or not, temperature place a part too, a little light cloud with the sun still coming through would have given a peak of 3.5kw in June as the panels would be cooler...

 

[BTB 500]

That's great data - very interesting. I did know that heat reduces the efficiency to some extent.

How does grime on the panels affect efficiency (hence my question about frequency of cleaning)? I assume they do need some attention, and aren't completely 'fit and forget'?

 

[Steveml63]

That's great data - very interesting. I did know that heat reduces the efficiency to some extent.

How does grime on the panels affect efficiency (hence my question about frequency of cleaning)? I assume they do need some attention, and aren't completely 'fit and forget'?

Hi,
I was a renewable energy specialist in the UK until end of 2012.
I supplied the first Solar Edge inverter plus micro-inverters in the UK - it was fitted on a house in South Wales with a big chimney in the centre of the roof - so 8 panels were fitted each side of the chimney.
Many of the higher quality panels have a catalytic coating on the top glass - this reacts with the dirt and breaks it down - so that next time it rains the dirt simply washes off.
Temperature plays a huge part in panel output.
In the UK, most panels have their output quoted at 25 degrees C and you lose around 0.5 per cent output per 1 degree increase in temperature.
Given that the panels are generally black (for mono-crystalline) or dark blue (for poly-crystalline) - they get pretty hot on a sunny summers day!
We often used to see the highest outputs from systems on a very sunny winters day (enough sometimes to trip the inverters!) - as the panels were cold enough to produce a very high output.
The Solar Edge system with individual micro-inverters for each panel were a real game changer for systems that we knew were going to have shading issue from big trees or chimneys during the day -as on a standard system shade on just one panel really drags the system down - due to the way they are wired to the inverter (normally two strings of 8 panels, wired in series for a typical 16 panel, 4kw system).
Cheers
Steve

 

[Piff]

They do have a "self cleaning" coating but that doesn't stop birds sh1ting on them or a general dust/dirt build up. Mine are at about 25 degrees slope so dirt buildup is worse than at a steeper pitch. I try to get up to hose them down once a year.
Ours were registered just before the tariffs were cut in 2012, so we are now getting £0.5536/kWh on generation & £0.039/kWh on 50% feed back to the grid. I have no idea how much we actually use ourselves. We have it hooked up to a 1.5kW immersion heater which kicks in when generation goes above 2.0kWh so in the summer we get some free hot water.
Our 3.705kW installation cost £7933 and so far we have received £16281 in payments

 

[Steveml63]

Hi,
I still work in sustainability, energy & water consultancy here in Abu Dhabi.
One project that I am working on is the tallest & largest zero energy building in the world.
Its the new HQ for DEWA (Dubai Energy & Water Authority)
The whole roof is solar panel equipped - as is much of the facade.
Internally it will be using AI technology to control the BMS (Building Management System) and is going to generate more electricity than it uses.
Here are some renders of the building!

Cheers
Steve

 

[MercedesDriver]

Some years ago the company I’ve worked for had a Solar Energy dept and remember to being told by the GPM that for any place above 45deg North the Solar is waste of money. In order to be viable source panels needs a lot of sunny hours throughout the year.
A map like this one was used on one of the sales trainings.

TBH I would rather invest in good thermal insulation than in Solar, at least here in UK.

 

[merc07]

Thermal insulation wouldn't heat my pool!
I have a 9kw heat pump (uses 2.1kw) of power and a 0.9kw pump.
The pump runs 8 hours from Apr - Oct, the heater 2-4 hours a day but I only run that when I have above 2kw of total power so I pay for max, 1 unit..
Begining to drop now, about 21.5C but that's nice in this heat !

 

[Steveml63]

Some years ago the company I’ve worked for had a Solar Energy dept and remember to being told by the GPM that for any place above 45deg North the Solar is waste of money. In order to be viable source panels needs a lot of sunny hours throughout the year.
A map like this one was used on one of the sales trainings.
View attachment 102377
TBH I would rather invest in good thermal insulation than in Solar, at least here in UK.

Some years ago - that might have been true - but solar panel technology has improved in recent years and global warming has probably increased the solar insolation in places like the UK.
Panels are very viable for producing power - however the Feed in tariffs that were enjoyed back in 2010 to 2013 are sadly long gone in the UK!

 

[John]

Thanks all.

I've looked at our usage and it seems we are running at around 3kW PA at the moment.

We fully LED'd up as of 3 years ago as I replaced bulbs as they went and replaced original bathroom / kitchen fittings at the end of life and have a fairly modern house (20 years old).

It sounds like batteries and taking advantage of cheaper energy could be the way to go if the maths works.

I guess in the future, when electric boilers take over from gas when they are phased out, electricity demand could well be higher and solar panels will make more sense.