Beginner solar panel install advice sought

[maverick278]

Dear experts,

I have been trying to get Solar panels fitted for well over a year, but the costs have been putting me off the whole of last year. Now, with electricity prices going through the roof, and with me purchasing an EV, I wanted to renew my aspirations to get Solar PVs installed soon.
However, the quotes I am getting seem way too expensive (I compared the prices of the actual components from the quote and they are selling it often at a premium of at least 150% compared to what I can get in the market)

So here are the details

I am a mid terraced town house with ground + 2 floors, with a 40degree inclined tiled roof facing proper south. However, since it is a mid terraced home, the roof is not that big, and we have a front elevation as well which shades a part of the roof (a small but appreciable part). The computer measured roof is about 5.9m X 4.2 m. I have had 3 quotes so far

Quote 1 - Total of 12 Panels ( 12 x SUNTECH 400W ) = 4.80kW MCS certification Full installation including all access equipment EPVS validation certificate HIES 10 year maximum consumer protection 10 Year Growatt Inverter Warranty 25 Year Panel Performance Warranty 10 Year Growatt Battery Warranty 2 years Workmanship Warranty All roof fixings/cabling/meter/Isolators/Ancillaries 18th Edition IET wiring regs RCD & surge protection if required Bird Protection for 12 Panels 1 x Growatt 6.5kW Battery & App 1 X Hybrid Solar Inverter.

This however uses the north side roof for 6 panels

£14358

Quote 2

Option 1 – 8 panels, Growatt with no battery - £8,190.00
Option 2 – 8 panels, Alpha with no battery - £9,470.00
Option 3 – 8 panels, Growatt 3.3 kWh battery - £10,130.00
Option 4 – 8 panels, Alpha 2.9 kWh battery - £11,610.00

Optional extra Myenergi Eddi 2.1 - Energy Diverter to Hot water tank - £860.00

Quote 3

Mono Deep blue 3.0 light Monocrystalline Solar Panels 415 W X 8
Foxess_Inverter
Smart Wifi
Bird Protection

£7315

When I compare the costs of the components to what these guys are quoting, they are at least double. Also, without batteries for 8 panels, if it is 8-10k, and reading these forums I won't be fully off grid, especially in winter, does this even make sense to me EV or otherwise? We consume about 2500KWH without the EV per year.

 

[binky]

Dear experts,

I have been trying to get Solar panels fitted for well over a year, but the costs have been putting me off the whole of last year. Now, with electricity prices going through the roof, and with me purchasing an EV, I wanted to renew my aspirations to get Solar PVs installed soon.
However, the quotes I am getting seem way too expensive (I compared the prices of the actual components from the quote and they are selling it often at a premium of at least 150% compared to what I can get in the market)

So here are the details

I am a mid terraced town house with ground + 2 floors, with a 40degree inclined tiled roof facing proper south. However, since it is a mid terraced home, the roof is not that big, and we have a front elevation as well which shades a part of the roof (a small but appreciable part). The computer measured roof is about 5.9m X 4.2 m. I have had 3 quotes so far

Quote 1 - Total of 12 Panels ( 12 x SUNTECH 400W ) = 4.80kW MCS certification Full installation including all access equipment EPVS validation certificate HIES 10 year maximum consumer protection 10 Year Growatt Inverter Warranty 25 Year Panel Performance Warranty 10 Year Growatt Battery Warranty 2 years Workmanship Warranty All roof fixings/cabling/meter/Isolators/Ancillaries 18th Edition IET wiring regs RCD & surge protection if required Bird Protection for 12 Panels 1 x Growatt 6.5kW Battery & App 1 X Hybrid Solar Inverter.

This however uses the north side roof for 6 panels

£14358

Quote 2

Option 1 – 8 panels, Growatt with no battery - £8,190.00
Option 2 – 8 panels, Alpha with no battery - £9,470.00
Option 3 – 8 panels, Growatt 3.3 kWh battery - £10,130.00
Option 4 – 8 panels, Alpha 2.9 kWh battery - £11,610.00

Optional extra Myenergi Eddi 2.1 - Energy Diverter to Hot water tank - £860.00

Quote 3

Mono Deep blue 3.0 light Monocrystalline Solar Panels 415 W X 8
Foxess_Inverter
Smart Wifi
Bird Protection

£7315

When I compare the costs of the components to what these guys are quoting, they are at least double. Also, without batteries for 8 panels, if it is 8-10k, and reading these forums I won't be fully off grid, especially in winter, does this even make sense to me EV or otherwise? We consume about 2500KWH without the EV per year.

it's not just cost of parts though, your scaffold will be over £1k at a rough guess for the height of your property. Demand is outstripping supply, so installers are charging accordingly. It's getting tempting to get MCS registered again given those prices!

Panels on North facing roof - why bother!

 

[bladerunnerpv]

There will be a markup from wholesale prices, remember they need to pay for wages, business premises, van, equipment, insurance etc

Have your quotes showed how much self consumption you'll get? I'd expect around 70% per annum to come from solar.

 

[Murdoch]

70% sounds optimistic

 

[bladerunnerpv]

that's prediction for a 8kWp E-W system in SE England with about 10kWh of battery too, I'll try a S only

 

[Bob Smith]

Dear experts,

I have been trying to get Solar panels fitted for well over a year, but the costs have been putting me off the whole of last year. Now, with electricity prices going through the roof, and with me purchasing an EV, I wanted to renew my aspirations to get Solar PVs installed soon.
However, the quotes I am getting seem way too expensive (I compared the prices of the actual components from the quote and they are selling it often at a premium of at least 150% compared to what I can get in the market)

So here are the details

I am a mid terraced town house with ground + 2 floors, with a 40degree inclined tiled roof facing proper south. However, since it is a mid terraced home, the roof is not that big, and we have a front elevation as well which shades a part of the roof (a small but appreciable part). The computer measured roof is about 5.9m X 4.2 m. I have had 3 quotes so far

Quote 1 - Total of 12 Panels ( 12 x SUNTECH 400W ) = 4.80kW MCS certification Full installation including all access equipment EPVS validation certificate HIES 10 year maximum consumer protection 10 Year Growatt Inverter Warranty 25 Year Panel Performance Warranty 10 Year Growatt Battery Warranty 2 years Workmanship Warranty All roof fixings/cabling/meter/Isolators/Ancillaries 18th Edition IET wiring regs RCD & surge protection if required Bird Protection for 12 Panels 1 x Growatt 6.5kW Battery & App 1 X Hybrid Solar Inverter.

This however uses the north side roof for 6 panels

£14358

Quote 2

Option 1 – 8 panels, Growatt with no battery - £8,190.00
Option 2 – 8 panels, Alpha with no battery - £9,470.00
Option 3 – 8 panels, Growatt 3.3 kWh battery - £10,130.00
Option 4 – 8 panels, Alpha 2.9 kWh battery - £11,610.00

Optional extra Myenergi Eddi 2.1 - Energy Diverter to Hot water tank - £860.00

Quote 3

Mono Deep blue 3.0 light Monocrystalline Solar Panels 415 W X 8
Foxess_Inverter
Smart Wifi
Bird Protection

£7315

When I compare the costs of the components to what these guys are quoting, they are at least double. Also, without batteries for 8 panels, if it is 8-10k, and reading these forums I won't be fully off grid, especially in winter, does this even make sense to me EV or otherwise? We consume about 2500KWH without the EV per year.

I won't repeat what @binky has said about the current market situation.

Have you had a return on investment calculation? What is their estimated generation per year?
You'll find here website that will let you estimate what you could expect from your solar

https://electricianforum.co.uk/thre...the-generation-in-kwh-of-the-pv-panels.55061/They are very conservative figures also because based on less efficient panels than these days so you can add 5 to 10%

The batteries make it more expensive but you can then better use what you generate. Exporting should be your last resource as what it is paid for but again you can calculate or ask your installer to provide calculation.

Your installation is too small to cover significantly your needs including your EV. In summer you will be able to put some kWh into your car but this will depend on factors such as the power (kW) (speed) at which you can charge. A 4.8kWp system will only on occasions delivery, only for a few minutes that power. Best of time you will be in the area of 3kW. If your car need 30kWh, you can see that it would be that your panels need to generate 3kW during 10 hours (I am ignoring the losses for simplicity). This is if you can charge your car at home during day time. At night, unless you have batteries but here again, your quoted batteries are small and will not really help you with your EV.

I would approach my ROI with respect to your home consumption.

Based of what you provided I would expect your system would generate about 4000kWh per year where 2/3 will be generated between April and October.
The batteries will help but also will help you in store cheaper energy from the grid (charge the batteries at night and use it in the day. This is often what we have to do in Winter).

You wrote you use 2500kWh per year maybe do you know your daily usage (difference between summer and winter). This should give you an indication about the size of the batteries.

As you can see your 12 panels will comfortably generate more electricity than what you consume. Unfortunately, the generation will not always be when you need the electricity.

Hope this helps. Happy to continue discussing details.

 

[Bob Smith]

70% sounds optimistic

Without batteries, I agree but with batteries (if they are sized correctly), I'll agree with Bladerunnerpv

 

[bladerunnerpv]

OK just playing around with free tools available on the web...

9x Perlight Delta 415W look like they'd fit the roof, 3735 kWp.
South facing aspect, 40deg pitch from horizontal, Postcode for Liverpool tourist info office, no shading
Using a Growatt string inverter and a Givenergy 3kW AC coupled, with 5.2kWh battery gives 67% of 2500kWh p.a. = 1687kWh supplied by the system, would be 35% without battery

 

[Bob Smith]

OK just playing around with free tools available on the web...

9x Perlight Delta 415W look like they'd fit the roof, 3735 kWp.
South facing aspect, 40deg pitch from horizontal, Postcode for Liverpool tourist info office, no shading
Using a Growatt string inverter and a Givenergy 3kW AC coupled, with 5.2kWh battery gives 67% of 2500kWh p.a. = 1687kWh supplied by the system, would be 35% without battery

Which tools are you using? Those I listed in the post I mentioned above?

The first one in the list gives for my 4kWp a generation of 3500kWh/y. Since 2016, I have generated an average of 3850kWh/y. (Cheshire)

 

[bladerunnerpv]

Hi Bob, the tool was easy-pv.

hmmm I could have written that more clearly...

The 1687kWh is the self-consumption value, some coming direct from solar and some from battery

The load is 2500kWh

1687/2500 is 67%, so that's the self-sufficiency value

The generation estimate is 3244kWh p.a.

Some kWh will be lost due to battery charge/discharge, nothing is 100% efficient.

the rest is exported to grid and which can make a little money back.

hope this helps

 

[Andy1733]

Dear experts,

I have been trying to get Solar panels fitted for well over a year, but the costs have been putting me off the whole of last year. Now, with electricity prices going through the roof, and with me purchasing an EV, I wanted to renew my aspirations to get Solar PVs installed soon.
However, the quotes I am getting seem way too expensive (I compared the prices of the actual components from the quote and they are selling it often at a premium of at least 150% compared to what I can get in the market)

So here are the details

I am a mid terraced town house with ground + 2 floors, with a 40degree inclined tiled roof facing proper south. However, since it is a mid terraced home, the roof is not that big, and we have a front elevation as well which shades a part of the roof (a small but appreciable part). The computer measured roof is about 5.9m X 4.2 m. I have had 3 quotes so far

Quote 1 - Total of 12 Panels ( 12 x SUNTECH 400W ) = 4.80kW MCS certification Full installation including all access equipment EPVS validation certificate HIES 10 year maximum consumer protection 10 Year Growatt Inverter Warranty 25 Year Panel Performance Warranty 10 Year Growatt Battery Warranty 2 years Workmanship Warranty All roof fixings/cabling/meter/Isolators/Ancillaries 18th Edition IET wiring regs RCD & surge protection if required Bird Protection for 12 Panels 1 x Growatt 6.5kW Battery & App 1 X Hybrid Solar Inverter.

This however uses the north side roof for 6 panels

£14358

Quote 2

Option 1 – 8 panels, Growatt with no battery - £8,190.00
Option 2 – 8 panels, Alpha with no battery - £9,470.00
Option 3 – 8 panels, Growatt 3.3 kWh battery - £10,130.00
Option 4 – 8 panels, Alpha 2.9 kWh battery - £11,610.00

Optional extra Myenergi Eddi 2.1 - Energy Diverter to Hot water tank - £860.00

Quote 3

Mono Deep blue 3.0 light Monocrystalline Solar Panels 415 W X 8
Foxess_Inverter
Smart Wifi
Bird Protection

£7315

When I compare the costs of the components to what these guys are quoting, they are at least double. Also, without batteries for 8 panels, if it is 8-10k, and reading these forums I won't be fully off grid, especially in winter, does this even make sense to me EV or otherwise? We consume about 2500KWH without the EV per year.

Those figures your quoting for usage is very low. And now you have the ev you will more than double those figures. I would say closer to 6000kwh per year. You also mention off grid. There's no way you can be off grid regardless of the money you throw at it. Your roof can take approx 8 panels. Your best option is to work with that and also a cheap overnight electricity rate (like octopus go) to reduce your reliant on the grid.

I have 4kw set-up with 9.6kw of battery's. I don't have a EV and over a year I'm covering about 55,% of my usage.

 

[offgridAndy]

If a limiting factor is the roof size. Then why not consider placing an array on the ground. I have 6.5Kw panels, all ground mounted with 4 different arrays. The position of each array is set to optimise production., ie they are not all set due south. some are more SE facing and one array is set to get afternoon sun (SW) in mid winter.

 

[Andy1733]

Guess this is something only maverick can answer. It the south facing side is to the front of the property and if the rear has ample space and no shading. My experience with mid terrace would be shading problems

 

[bladerunnerpv]

Just some additional thoughts for the mix...

Charge the EV primarily from cheaper overnight electricity as some others on the forum do ?

Octopus has/had a 4h cheap overnight elec tariff, other suppliers have their own tariffs

IIRC the Zappi charger is 7kW, in 4h that's approx. 28kWh available at min. price.


Could just go for AC coupled inverter with batteries and skip the panels, save about 9*200 for panels +500 for string inverter = £2300 (wholesale) ?
with a 3kW AC coupled inverter that's 4h*3kW = 12kWh which could be stored at min. elec price, but would need to increase the battery storage accordingly, which would wipe out the saving?

so zappi + battery is approx 40kWh, without solar PV, all at economy tariff
not sure what size the car battery would be.

solar PV system to supplement for 6-9m of the year?

There's an optimum way to do it to be found if the priority is for EV charging.

Others with EVs can advise better than myself

 

[maverick278]

wow - thank you all for such detailed PoVs..

My electricity usage from Nov '21 to Nov '22 is only 1575 kwh. I think it is pretty low, but we are a family of 4, have LED lights all throughout and our usage per se is very minimal. This time period does not include EV though, as EV only happened in Dec '22. Since buying the EV, I have not done any big road trips (with it being winter and all) and even if I account for 6-7 road trips each comprising of 800 miles round trip (very high but to keep the calculations pessimistic) that is about 8K miles per annum. Assuming I charge 75% at home, that is 6000 miles to be charged at home year round (more so in summer than in winter). Mine is a Tesla Model Y LR with a 77 kwh battery. I get about 2.5 miles (average) per kwh as I live in a hilly area and even during road trips, it is likely this will be a big factor in the UK. So for me to charge 6000 miles at home, I need to generate 2400 kwh and splitting the road trips between summer and winter as (70/30) I would need to generate approx 1800 kwh on an average across all of spring/summer and autumn months just for my EV.

So overall with the EV, and making up for more usage of appliances owing to Solar PVs, if I up the annual consumption to 2400 kwh + 1800 kwh for the EV, this effectively means I would need 4.2 kwh system to be able to make this worth my while. (Please correct my calc if I have made any rookie errors)

The quotes I have received are okayish, but a couple of them have said they can only ever fit 5-6 panels and a few others have said they can fit 8 panels. So I am a bit worried that after putting up the deposit and the scaffolding, if they go up the roof and say hey, we can only do 5-6 panels, I am looking at a very underpowered system right? I would have no choice but to go with it as the deposit will be at stake. So I am really not sure what to do here. I am attaching the roof picture for your reference.

I am also thinking about a battery only operation. Our daily routine starting September is going to be just my daughter's school pick up and drop off and some class pick up and drop off during the week, and some trips/costco/grocery runs during the weekend. So I envisage us doing no more than 100 miles a week and so it would mean I need 25 kwh per week with or without Solar PVs (excluding any road trips that is) and so I also thought about putting up enough batteries without the PVs as well.

So my RoI calculations need to be looked at for sure based on the above calcs. Based on the above, is Solar even an option for me? And about ground level panels, unfortunately there is a lot of trees on the north side, and so plenty of shading which negates this option :/ When we bought this house, we did not think about these things, but then we did not envisage we will have to struggle with such exorbitant charges for utilities either which is forcing us to rethink. Of course I would love to go green, but I have also saved up to install Solar PVs, and if this is not viable, not want to go ahead. If you guys need any measurements, I can provide those too

Apologies I did not get notified about the new replies to my thread and so my tardiness in responding

 

[bladerunnerpv]

Hi maverick,

"The computer measured roof is about 5.9m X 4.2 m."

I'm wondering how many kWp you can actually fit to that roof. How was the roof computer measured ?

I expect this has already been done, but just to be sure, what does the tape measure say if you measure across your property? Does it make sense against 5.9m?

Is 4.2m the maximum extent from ridgeline to gutter, not taking the cream wall into account, if so the area available for PV would have to reduce.

by eye that looks like it could be limited to 6panels at most, measurement would confirm

The perlight 415W panels, picked at random pretty much, are 1719 x 1140 x 30mm, so in landscape orientation 3x2 panels is 5.157m x 2.280m (plus any fitting tolerance, I'm just doing the arithmetic!)

425W panels are around in very similar size, so 425W x 6 = 2.550 kWp

that gives 785kWh p.a. from solar, 671kWh p.a. from 5.2kWh battery, total 1507kWh p.a. = 60% of your 2500kWh p.a. usage

import 1050kWh p.a. from grid,

export 678kWh p.a. to grid (or to water heating or EV)

increasing the battery to 9.5kWh only adds about 50 kWh p.a., but would allow you to store a more economy7 energy

assuming a 40kWh EV car battery, then your export would be equivalent to 680/40 = 16 full charges p.a., or assuming margin at top and bottom so only using 70%(?) of battery, then 16/.7 = almost 23

so the solar won't power the EV, it just gives you a nice electricity saving of 60% + whatever the export could be diverted to

EDIT:
on 1575 kWh p.a. usage at home then that's a better situation

with 9.5kWh battery 3kW AC coupled inverter and a 3kW string inverter

give generation ~2200 kWh p.a.

that gives consumption 563kWh p.a. from solar, 577kWh p.a. from 5.2kWh battery, total 1140kWh p.a. = 73% of your 1575kWh p.a. usage

import 437 kWh p.a. from grid,
export 1008 kWh p.a. to grid (or to water heating or EV)

1008/40/0.70 = 36 charges of the EV

(smaller 5.2kWh battery drops self consumption by about 25kWh, so more import and more export)

hope this helps

 

[maverick278]

bladerunnerpv - you are spot on with your analysis, owing to the cream coloured wall that raises above the roofline, and since some of my roof is lost on the left hand side owing to the raised roof next to it, effectively, I can only see anyone able to fit 6 panels. One query I had was, the cream coloured wall face poses a partial shadow risk (the roof actually runs all the way down) is it absolutely a no-no to put panels on with partial shadow (not sure when the shadow will take over though)

I just want to ensure that it would be worth my while to do 6 panels. So what would be your recommended set up?

6X425 kwh panels + 9.5kWh battery storage + eddy diverter for my hot water?

Thank you for the guidance

 

[bladerunnerpv]

Hi maverick, hope it has helped you think through the factors in making your decision.

Please note I'm a complete amateur, just playing with the free tools and doing lots of research, so sorry but I'm not going to make "a recommendation", other than to have a go with the free tools and try different options if you have time and inclination. A proper installer should be able to answer your questions better than me.... Hopefully other forumites will put me straight if I've made any howlers

Personally I'd go with the larger 9.5kWh battery, seen more positive noises here in last 6m about Eddi than iBoost... but a small sample set so who knows.

wrt. "...no-no to put panels on with partial shadow ...". No, but...

you'll probably find better answers elsewhere on the forum on this one, but I'll try and pitch in from what I've learned here

It's possible to use something like enphase microinverters, the basic idea of which is to put an inverter on each panel rather than feed the panels into a string inverter, then the individual panels respond, well, individually. If several panels are connected in series then one 'shaded' one might result in a bottleneck (check elsewhere on this effect, I'm not clear exactly how bad this can get)

Don't know if feasible to do a mix of enphase for some panels and standard string inverter for other.

But enphase are rather expensive (£160 each wholesale) and apparently need an 'envoy device' each (£175 wholesale) so not looking like a value for money solution!

SMA inverters have "Shadefix" which, you'd never guess, is apparently to help with shading problems. No idea of how good they are in practise or limitations, I'm sure some web searching will explain it.

If the string voltage is enough from 2 panels then you could use an inverter with two MPPT trackers (most do it seems) and could feed 2 panels into one inverter MPPT input and the other 6 into the other MPPT input. You would need to check the startup voltage of the inverter and calculate the string voltage from the two panels, otherwise the energy from the 2 panels might never be used!

If the cost/benefit is worth it you might be able to use two differently sized inverters and connect 6panels to one and 2 to the other for example. Maybe a 1000W inverter for 2 panels, just looked at growatt and the startup was 50V for that one, and a 2.5kW inverter for the 6 panels. Just speculating here.

Not easy to do that with hybrid inverters though as they would need some way to communicate to manage battery charging if feeding from both into one battery. Some can do this, but not common AFAIK. So using two inverters is likely to push you down the AC coupled route.

Enjoy !

Thread locked to prevent hi-jacking

 

[Bob Smith]

Go and check some of his videos. Don t worry there aren't many

https://www.youtube.com/@GaryDoesSolar/videosMost of your questions about string inverter, micro inverter and optimizer should found an answer there.
PS: There are 2 videos about microinverter, make sure you watch the second because in the first one he missed a point. One can always learn..

PS: It's not me