Solar Panels?

[MaxFromage]

Dave726 said:

Looking for a reality check on the solar potential of my property.

(Created a new login for obvious reasons hence post number 1)

Due to having a swimming pool heat pump, central heating system with a myriad of pumps, 6 MVHR units, Crestron AV & lighting and an over the top intruder and fire alarm system (fitted by a previous owner) my annual consumption is about 27,000kWh.

I’m working to reduce this as there are definitely some things that can be improved but even so ongoing consumption is still going to be high.

I’ve had a couple of quotes for solar as follows:
1. Circa 20kWP which has an estimated annual generation of 15kWh and an optional 17.6kWh battery. Solar element is £26,460 and battery is £6,500. For reference this was a quote from mid May so prices may be up given current demand. Quote doesn’t look like it includes scaffolding but I need to replace the flat roof anyway as it has a small leak so let’s ignore this for simplicity.

2. Circa 35kW (not sure if this is really possible given it is 94 panels) with estimated annual generation of 30kWh for £32,300. Quote is again unclear as to whether it is inclusive of scaffolding and, again, is from mid May.

My query is whether my calcs are correct as I am getting a much shorter break even period than most I have seen quoted. Based on current prices at 30ppkWh and assuming I use all the power generated (let’s ignore battery for the time being) the payback periods are 5.9 years and 3.6 years respectively. Should the forecast price increases of 70ppkWh and 100ppkWh materialise and last even for 6-12 months these will significantly reduce those timescales.
I’m aware that peak power generation in April-September especially in quote 2 may exceed my hourly usage but I’m leaning towards quote 1 anyway where I don’t believe this will be a problem and the battery is probably not required.

One other option is that these quotes are based on 380w panels whereas I have found a supplier with JA Solar 540w panels available. Assuming I could substitute for these the estimated 15kWh of generation theoretically increases to 21kWh making it even more attractive (but requiring more work to see whether a battery is needed).

Can anyone do a reality check on this and let me know any obvious issues I haven’t considered please? Thanks in advance.

We have just had 16.4kw installed for £17K. That's commercial and includes all costs including scaffolding. We use around 33,000 kwh per annum. You do need to match energy usage withe the size of the array. I worked ours out and the contractors confirmed the calculations. You may have significant excess generation at times, even with the smaller array given the spread of when generation occurs (search for the PVGIS website). How much does the pool pump use (and when?). Breakeven will be less than 5 years at 32p per kwh on ours (our current rate).

[Jambo85]

PAT64 said:

Random question, does that number on the inverter that reads 380-400watts (it keeps changing) mean this is how much watts its currently producing for my home?

My installer did not give me the app or login/password details but they have kept it for themselves on their mobile phone due to it being a government green scheme set up, so apart from the emlite white monitor box near my electrical board saying 300.00 khw or looking at the inverter itself this appears the only way I can see what's being generated I think.

Do you have a photo of what you’re looking at?

[Dave726]

MaxFromage said:

We have just had 16.4kw installed for £17K. That's commercial and includes all costs including scaffolding. We use around 33,000 kwh per annum. You do need to match energy usage withe the size of the array. I worked ours out and the contractors confirmed the calculations. You may have significant excess generation at times, even with the smaller array given the spread of when generation occurs (search for the PVGIS website). How much does the pool pump use (and when?). Breakeven will be less than 5 years at 32p per kwh on ours (our current rate).

Thanks for the response.

I guess your break even figures confirm my main query. These higher electricity prices (and probably also the improving output of solar panels) have surely totally changed the viability of solar. If the forecast electricity price rises materialise and last for any reasonable period it’s going to make it an absolute no brainer for almost everyone.

[Temo_Wil]

Dave726 said:

MaxFromage said:

We have just had 16.4kw installed for £17K. That's commercial and includes all costs including scaffolding. We use around 33,000 kwh per annum. You do need to match energy usage withe the size of the array. I worked ours out and the contractors confirmed the calculations. You may have significant excess generation at times, even with the smaller array given the spread of when generation occurs (search for the PVGIS website). How much does the pool pump use (and when?). Breakeven will be less than 5 years at 32p per kwh on ours (our current rate).

Thanks for the response.

I guess your break even figures confirm my main query. These higher electricity prices (and probably also the improving output of solar panels) have surely totally changed the viability of solar. If the forecast electricity price rises materialise and last for any reasonable period it’s going to make it an absolute no brainer for almost everyone.

That’s my opinion as well. My 4.05kw + 11.6kwh battery system is costing £11,700. South facing property with nearly perfect pitch, no shade and located in the SE should bring in a realistic minimum 4,000kwh per annum (I’m hoping for closer to 4,700 but will wait and see). With the battery I’ll be able to use virtually all of that myself. At 80p kWh forecast for Jan 23 the payback will be 3.5years. Of course that all depends on the prices staying high but I can’t see them coming down much in the next 2 years with what’s going on politically. This makes it as you put… a no brainer.

[tuscan_raider]

MaxFromage said:

We have just had 16.4kw installed for £17K. That's commercial and includes all costs including scaffolding. We use around 33,000 kwh per annum. You do need to match energy usage withe the size of the array. I worked ours out and the contractors confirmed the calculations. You may have significant excess generation at times, even with the smaller array given the spread of when generation occurs (search for the PVGIS website). How much does the pool pump use (and when?). Breakeven will be less than 5 years at 32p per kwh on ours (our current rate).

Max, that sounds very similar to what Im looking at ' 17Kw ground mounted with batteries.

I had a quote done about a year ago (30K) and I need to get it updated (technologies and payback all different now) can you send me details and advice (get an installer or do it mysel etc)? Thanks

[MaxFromage]

tuscan_raider said:

Max, that sounds very similar to what Im looking at ' 17Kw ground mounted with batteries.

I had a quote done about a year ago (30K) and I need to get it updated (technologies and payback all different now) can you send me details and advice (get an installer or do it mysel etc)? Thanks

If you're a registered electrician, you could do it yourself for about £12K with batteries... Otherwise it's how much effort you want to go to, building the array yourself and then getting someone to sign it off. Our installer only does local installs so I don't have any details to pass on I'm afraid.

[nunpuncher]

I'm having a real problem even getting companies to give quotes for solar and batteries. The industry seems to be like the double glazing industry in the 1980s right now. 2 companies have sent "surveyors" that have turned out to be salesmen (both appeared to be just out of school). No kowledge beyond the basic system that doesn't require planning and only interested in getting you to sign up right there and then with fanciful projections. 1 other wasn't interested the minute I mentioned using the interest free Scottish government loan as they said the boss wasn't prepared to wait for his money.

So far I've only spoke to 1 out of about 10 companies that didn't seem like an absolute cowboy.

[monkfish1]

nunpuncher said:

I'm having a real problem even getting companies to give quotes for solar and batteries. The industry seems to be like the double glazing industry in the 1980s right now. 2 companies have sent "surveyors" that have turned out to be salesmen (both appeared to be just out of school). No kowledge beyond the basic system that doesn't require planning and only interested in getting you to sign up right there and then with fanciful projections. 1 other wasn't interested the minute I mentioned using the interest free Scottish government loan as they said the boss wasn't prepared to wait for his money.

So far I've only spoke to 1 out of about 10 companies that didn't seem like an absolute cowboy.

Thats seems to be about the current situation. Free government money brings out the fly by night chancers.

Im DIYing it.

i do however sympathise with the guy saying no to waiting to get paid. When we ran the workshop it was a simple no warranty company dealings. Invariably, you would spend longer chasing payment than you ever did fixing the car. At half the actual labour rate usually. Customer was welcome to make a claim themselves.

[r3g]

nunpuncher said:

I'm having a real problem even getting companies to give quotes for solar and batteries. The industry seems to be like the double glazing industry in the 1980s right now. 2 companies have sent "surveyors" that have turned out to be salesmen (both appeared to be just out of school). No kowledge beyond the basic system that doesn't require planning and only interested in getting you to sign up right there and then with fanciful projections. 1 other wasn't interested the minute I mentioned using the interest free Scottish government loan as they said the boss wasn't prepared to wait for his money.

So far I've only spoke to 1 out of about 10 companies that didn't seem like an absolute cowboy.

That's the reason why no company is interested. Put yourself in their shoes. If you want an actual installation this century you'll need to pony up the cash yourself.

[g40steve]

When So Energy did my survey the chap was outside on the cul de sac for about an hour taking all sorts of measurements & elevation using a tripod before he even entered the house to do the rest.

Mick & his van van cash only beware

[nunpuncher]

Unfortunately the government money isn't free. It's an interest free loan that I pay back in full.

I'm just amazed that I'm finding it so hard to find a professional established company in this area operating in my location in Scotland.

[Evanivitch]

g40steve said:

When So Energy did my survey the chap was outside on the cul de sac for about an hour taking all sorts of measurements & elevation using a tripod before he even entered the house to do the rest.

Mick & his van van cash only beware

Why? There's loads of online tools available that assess the pitch and direction of your roof. It takes 2 minutes, and the generation data is an approximation based on historical data at best.

If anything, I'd be more suspicious of someone taking half an hour taking pointless measurements.

[OutInTheShed]

Dave726 said:

Thanks for the response.

I guess your break even figures confirm my main query. These higher electricity prices (and probably also the improving output of solar panels) have surely totally changed the viability of solar. If the forecast electricity price rises materialise and last for any reasonable period it’s going to make it an absolute no brainer for almost everyone.

I hate the phrase 'no brainer'. It seems quite often to be used by people who are reluctant to exercise their brain on an issue.

Here's a little reality check.
My electricity use is something like 3000kWh a year. That's about £850 at today's price

A lot of that is in the Winter. In Summer it's more like 7kWh a day, compared to roughly 10kWh a day in a winter month.

I don't have smart meter data to slice and dice my power use by the hour, but a lot is lighting and other things like tumble drier which have what you might call a strong negative correlation with 'sunshine'. Then there's 2 fridges and a freezer running 24/7.

My rough calculations, based on living in the Sunny South, suggest that if I had a 4kW set of panels, I could chop somewhere between 20 and 30% off my bill. Call it £250 at most. Then I might get something like 4000kWh of export at most, at about 5p a unit, that's £200. Total £450

So payback on a simple panel system is a bit meh.

Add in a battery and the estimate requires a bit more of my meagre brain, to work out how many days I can usefully charge the battery to cover my evening power use. Not having enough data of great quality, I'd say maybe 200 days a year, so that looks roughly like saving 55% of my bill, about £470 per year at today's price. That needs about 7kWh of battery. I think I'd still be exporting 2500kWh or so, call it £125. Total 'saving' £595.

Again, payback is meh!

So, as far as I can see, it needs prices to go up a lot more to make a great case for home solar.
If you use all that power which I'd expect to export, then it's very different. So if you have an office with a lot of PCs and aircon and/or a BEV you drive a lot at night in the summer, you might be quids in. Note: 'might'.


If you work on say double today's electricity prices, then you are still up against prices for solar and batteries being artificially high right now.

It's a fag packet analysis, but the solar fanbois are notably lacking in anything better on the whole.

[g40steve]

Evanivitch said:

Why? There's loads of online tools available that assess the pitch and direction of your roof. It takes 2 minutes, and the generation data is an approximation based on historical data at best.

If anything, I'd be more suspicious of someone taking half an hour taking pointless measurements.

Here we go another know it all.

I filled in the online portal using Google maps image of my house & mapped the outline of roof area.

But this does not show my internal roof structure, where my G&E boxes or consumer unit are, where I would like the battery, inverter & associated gubbins & all the other stuff like scaffolding.

[g40steve]

OutInTheShed said:

I hate the phrase 'no brainer'. It seems quite often to be used by people who are reluctant to exercise their brain on an issue.

Here's a little reality check.
My electricity use is something like 3000kWh a year. That's about £850 at today's price

A lot of that is in the Winter. In Summer it's more like 7kWh a day, compared to roughly 10kWh a day in a winter month.

I don't have smart meter data to slice and dice my power use by the hour, but a lot is lighting and other things like tumble drier which have what you might call a strong negative correlation with 'sunshine'. Then there's 2 fridges and a freezer running 24/7.

My rough calculations, based on living in the Sunny South, suggest that if I had a 4kW set of panels, I could chop somewhere between 20 and 30% off my bill. Call it £250 at most. Then I might get something like 4000kWh of export at most, at about 5p a unit, that's £200. Total £450

So payback on a simple panel system is a bit meh.

Add in a battery and the estimate requires a bit more of my meagre brain, to work out how many days I can usefully charge the battery to cover my evening power use. Not having enough data of great quality, I'd say maybe 200 days a year, so that looks roughly like saving 55% of my bill, about £470 per year at today's price. That needs about 7kWh of battery. I think I'd still be exporting 2500kWh or so, call it £125. Total 'saving' £595.

Again, payback is meh!

So, as far as I can see, it needs prices to go up a lot more to make a great case for home solar.
If you use all that power which I'd expect to export, then it's very different. So if you have an office with a lot of PCs and aircon and/or a BEV you drive a lot at night in the summer, you might be quids in. Note: 'might'.


If you work on say double today's electricity prices, then you are still up against prices for solar and batteries being artificially high right now.

It's a fag packet analysis, but the solar fanbois are notably lacking in anything better on the whole.

Still waiting for house prices to drop?

[Jambo85]

nunpuncher said:

Unfortunately the government money isn't free. It's an interest free loan that I pay back in full.

I'm just amazed that I'm finding it so hard to find a professional established company in this area operating in my location in Scotland.

I know from experience there’s a few hoops to jump through before you get the cash in your account - e.g. you need an EPC done after the install. Sounds like the installers can probably choose jobs so they’ll choose the ones that suit them. 50% deposits and balance within a week.

2-3 men in a van can install £10k of kit in a day, so if everyone is taking 60 days to pay that’s a lot of cash outstanding for a small business - I can see their point unfortunately.

[Griffith4ever]

OutInTheShed said:

I hate the phrase 'no brainer'. It seems quite often to be used by people who are reluctant to exercise their brain on an issue.

Here's a little reality check.
My electricity use is something like 3000kWh a year. That's about £850 at today's price

A lot of that is in the Winter. In Summer it's more like 7kWh a day, compared to roughly 10kWh a day in a winter month.

I don't have smart meter data to slice and dice my power use by the hour, but a lot is lighting and other things like tumble drier which have what you might call a strong negative correlation with 'sunshine'. Then there's 2 fridges and a freezer running 24/7.

My rough calculations, based on living in the Sunny South, suggest that if I had a 4kW set of panels, I could chop somewhere between 20 and 30% off my bill. Call it £250 at most. Then I might get something like 4000kWh of export at most, at about 5p a unit, that's £200. Total £450

So payback on a simple panel system is a bit meh.

Add in a battery and the estimate requires a bit more of my meagre brain, to work out how many days I can usefully charge the battery to cover my evening power use. Not having enough data of great quality, I'd say maybe 200 days a year, so that looks roughly like saving 55% of my bill, about £470 per year at today's price. That needs about 7kWh of battery. I think I'd still be exporting 2500kWh or so, call it £125. Total 'saving' £595.

Again, payback is meh!

So, as far as I can see, it needs prices to go up a lot more to make a great case for home solar.
If you use all that power which I'd expect to export, then it's very different. So if you have an office with a lot of PCs and aircon and/or a BEV you drive a lot at night in the summer, you might be quids in. Note: 'might'.


If you work on say double today's electricity prices, then you are still up against prices for solar and batteries being artificially high right now.

It's a fag packet analysis, but the solar fanbois are notably lacking in anything better on the whole.

Indeed - if FITs don't improve significantly, then solar is only justified IF you can use the power you generate, OR, batteries become huge and cheap.

As it stands, the government should be increasing feed in tarrifs to encourage us all to generate power and top up the grid. But of course, they are not, because, stupid.

[TDK-C60]

monkfish1 said:

nunpuncher said:

I'm having a real problem even getting companies to give quotes for solar and batteries. The industry seems to be like the double glazing industry in the 1980s right now. 2 companies have sent "surveyors" that have turned out to be salesmen (both appeared to be just out of school). No kowledge beyond the basic system that doesn't require planning and only interested in getting you to sign up right there and then with fanciful projections. 1 other wasn't interested the minute I mentioned using the interest free Scottish government loan as they said the boss wasn't prepared to wait for his money.

So far I've only spoke to 1 out of about 10 companies that didn't seem like an absolute cowboy.

Thats seems to be about the current situation. Free government money brings out the fly by night chancers.

Im DIYing it.

i do however sympathise with the guy saying no to waiting to get paid. When we ran the workshop it was a simple no warranty company dealings. Invariably, you would spend longer chasing payment than you ever did fixing the car. At half the actual labour rate usually. Customer was welcome to make a claim themselves.

I can't get much joy either. Things like panels and batteries seem to be available so I wonder if the bottleneck is just in the resources to install - and the limited number of installers is just fully booked for ages.

I understand you need a MCS certified to put solar back into the grid - but it does seem like a roofer could put the panels (and microinverters) on the roof and an electrician could install a hybrid inverter and battery and connect it up.

Can you buy the kit and get subbies to install it?

[OldSkoolRS]

OutInTheShed said:

I hate the phrase 'no brainer'. It seems quite often to be used by people who are reluctant to exercise their brain on an issue.

<SNIP>

If you work on say double today's electricity prices, then you are still up against prices for solar and batteries being artificially high right now.

It's a fag packet analysis, but the solar fanbois are notably lacking in anything better on the whole.

Don't come on here spouting your sensible calculations. As I've said here and elsewhere; solar panels/batteries have to be worked out on a case by case basis and it doesn't work for everyone, especially if the bulk of their use is in the evening. I also don't think it's a sensible long term plan to expect the cheap night rates to continue, so you can charge up a battery overnight for less then use it during the day.

I've wrestled with the calculations a lot recently, but so far I'm just focusing on reducing usage as a priority by using common sense and failing that, spotting things I'd missed by using a recently installed smart meter.

I've got my usage down to around 4.5kwh per day, but this is summertime (just) and I'm fully aware that the longer evenings will increase the (LED) lighting we use, plus I hadn't realised how much power the CH takes when pumping the water around the house, so that's a not inconsiderable amount of extra electricity I'll need when the sun isn't shining and/or it's cold outside. Last winter we used 15% more electricity than the previous summer, but I think that might be a bit optimistic to expect only 15% on top of our newly reduced figure of 4.5kwh. I'd be happy if it came in at around 7kwh per day this winter. That would bring my annual total to around 2100kwh, or just over £1,000 at the October cap of 52p (if that still happens of course).

Given the prices of some quotes I've seen recently, even if I saved ALL of that money I'd be looking at maybe 12 years to reach ROI. While I've seen some useful real world figures averaged over the last 7 years from one solar panel owner with a 4kW system, it doesn't seem like I'd be able to recover all of the above. His figures suggested I'd be under for November to February, so even at the higher prices of electricity, it seems that it's then cancelled out by the price hikes on the installations now. Perhaps it's just because I picked a bad time, but at the moment I'm not rushing to have an installation done at these prices. I think it makes more sense just to cut down as much as I can in the meantime, but that might not be possible or practical for other people, especially if they have young children or older people living with them who naturally need more energy use to take care of them.

I'm hoping that there is a return to more realistic prices for installations, though perhaps that is optimistic: It's not like I'll be getting one installed anytime soon anyway given the current demand.

I do agree though; I hate the term 'no brainer' and I don't think it always applies to solar panel systems as much as some Fanbois might want them to.

Edited by OldSkoolRS on Tuesday 6th September 20:45

[Dave726]

OutInTheShed said:

I hate the phrase 'no brainer'. It seems quite often to be used by people who are reluctant to exercise their brain on an issue.

Here's a little reality check.
My electricity use is something like 3000kWh a year. That's about £850 at today's price

A lot of that is in the Winter. In Summer it's more like 7kWh a day, compared to roughly 10kWh a day in a winter month.

I don't have smart meter data to slice and dice my power use by the hour, but a lot is lighting and other things like tumble drier which have what you might call a strong negative correlation with 'sunshine'. Then there's 2 fridges and a freezer running 24/7.

My rough calculations, based on living in the Sunny South, suggest that if I had a 4kW set of panels, I could chop somewhere between 20 and 30% off my bill. Call it £250 at most. Then I might get something like 4000kWh of export at most, at about 5p a unit, that's £200. Total £450

So payback on a simple panel system is a bit meh.

Add in a battery and the estimate requires a bit more of my meagre brain, to work out how many days I can usefully charge the battery to cover my evening power use. Not having enough data of great quality, I'd say maybe 200 days a year, so that looks roughly like saving 55% of my bill, about £470 per year at today's price. That needs about 7kWh of battery. I think I'd still be exporting 2500kWh or so, call it £125. Total 'saving' £595.

Again, payback is meh!

So, as far as I can see, it needs prices to go up a lot more to make a great case for home solar.
If you use all that power which I'd expect to export, then it's very different. So if you have an office with a lot of PCs and aircon and/or a BEV you drive a lot at night in the summer, you might be quids in. Note: 'might'.


If you work on say double today's electricity prices, then you are still up against prices for solar and batteries being artificially high right now.

It's a fag packet analysis, but the solar fanbois are notably lacking in anything better on the whole.

You’ve got to love these forums. Because it doesn’t work for you, anyone else that is in favour of it (especially those that it does clearly make sense for) hasn’t done any work on the issue (even though you admit you don’t have a smart meter and have only done fag packet analysis…) and is a ‘fanbois’.

Brilliant.

My break even period is 5.5 years at todays electricity prices which equates to a ROI of 18%. I’d be delighted to hear why you think that’s a bad idea for me, or any other ‘fanbois’ &#128514; in a similar situation.