Solar - where to start?

[8bit]

We live in a 1930's granite semi-detached in Aberdeen. There's a kitchen extension with a good amount of south-facing roof (Sarnafil) and a reasonable amount of traditional slate roof, also south-facing. A similar house a few doors up have eight panels on their original roof so I assume ours will be the same, can maybe get 10 on the Sarnafil roof.

Wife and I both work from home full time. We have an EV and a home charger which we currently charge on a cheap overnight tarriff with E.On. Heating is mostly gas (couple of bathrooms with electric underfloor heating but not used much).

I did plug our details into Uswitch and got an estimate of about £10k based on 12 panels and a battery system. I've no idea if that's realistic as I've nothing to compare it against. I see some ads on social media for Scottish Solar Grants but can't find anything official looking online so I'm assuming these are not exactly legit, but maybe there are options there? Where is good to find independent, realistic advice for this stuff?

[AyBee]

I'd start with a couple of quotes and I'd probably try your energy supplier as one of them (they will likely sub-contract) and then look at other houses nearby and see if you can find a local supplier or 2 for other quotes. Travel and overnight accommodation will be a not insignificant part of the cost if you go with someone who isn't local so you may find that the economies of scale they're able to achieve doesn't offset that cost.

Do you want a battery as well? If so, it's probably worth doing some research about which one you might want from an integration/app perspective because that will likely have some impact on which installer.

Will you need finance, because that may also impact choice of installer - if you do, it's probably worth waiting until the Warm Homes Loan Scheme comes into force later this year because rates will drop.

[kambites]

For what it's worth we've just decided to proceed with a quote for 16 panels (just under 8kW total) plus 16kWh (usable capacity) of batteries with whole-home UPS backup for just under £12000. That's in Hampshire.

We asked around for recommendations on local forums, etc. as well as asking friends. We ended up getting, I think, 5 or 6 quotes which varied from 12k up to about 18k, albeit with a slight variation on what was being installed depending on which suppliers (especially battery/inverter suppliers) the installers worked with. All of the quotes were from independent companies within about a 30 mile radius except Octopus, who subcontract to local companies and who were pretty uncompetitive anyway.

Edited by kambites on Wednesday 26th August 11:04

[Byker28i]

Octopus quoted me £10.2K for 5kw of panels (11x440w), 5kw of battery. Our council was doing the Solar Together scheme, so I got the same under that for £5700

Have your council got any incentives/schemes?

[gangzoom]

kambites said:

For what it's worth we've just decided to proceed with a quote for 16 panels (just under 8kW total) plus 16kWh (usable capacity) of batteries with whole-home UPS backup for just under £12000. That's in Hampshire.

Not sure how built up the area is, 8KW is a big array for an urban setting. The max our DNO would allow was 5KW.

[8bit]

AyBee said:

I'd start with a couple of quotes and I'd probably try your energy supplier as one of them (they will likely sub-contract) and then look at other houses nearby and see if you can find a local supplier or 2 for other quotes. Travel and overnight accommodation will be a not insignificant part of the cost if you go with someone who isn't local so you may find that the economies of scale they're able to achieve doesn't offset that cost.

Do you want a battery as well? If so, it's probably worth doing some research about which one you might want from an integration/app perspective because that will likely have some impact on which installer.

Will you need finance, because that may also impact choice of installer - if you do, it's probably worth waiting until the Warm Homes Loan Scheme comes into force later this year because rates will drop.

Thanks for all that. I'll see if E.On have any offerings. I've no idea if we want a battery or not - we work from home so I'd have thought we'd be using most/all of the energy the panels will generate during the day. I'll look at the Warm Homes thing too, cheers.

Byker28i said:

Octopus quoted me £10.2K for 5kw of panels (11x440w), 5kw of battery. Our council was doing the Solar Together scheme, so I got the same under that for £5700

Have your council got any incentives/schemes?

Doesn't look like it unfortunately, but then I do live in the "Oil Capital of Europe"

gangzoom said:

kambites said:

For what it's worth we've just decided to proceed with a quote for 16 panels (just under 8kW total) plus 16kWh (usable capacity) of batteries with whole-home UPS backup for just under £12000. That's in Hampshire.

Not sure how built up the area is, 8KW is a big array for an urban setting. The max our DNO would allow was 5KW.

What is a DNO?

[soad]

Distribution Network Operator?
https://www.energynetworks.org/energy-networks-exp...

[Steve H]

From our POV with solar, if you want to be able to export power to the grid you have to apply to see how much you can export, that’s often referred to as the DNO.

I think there’s a minimum that they have to allow (about 3kw?) and the rest depends on a few factors like proximity of your transformer, how many other properties are on it etc.

We are rural and fairly well placed it seems as we are allowed 10kw which we run off a 20kw system. It cost a bit over £20k with 20kwh of battery storage although we have added a further 10kwh to that since.

[clockworks]

With an EV, and an EV tarrif, have a look at going for battery only, no solar.

A big enough battery, charged overnight on 8p electric, will more than halve your electricity bill.

Next step, replace gas with a heat pump. Combined with a bigger battery, heat your house on 8p electricity (at 350% efficiency), a third of the cost of gas.

There are plenty of options unlocked by having an EV tarrif. Explore the potential savings and up-front costs of all the options before spending any money.

[kambites]

gangzoom said:

Not sure how built up the area is, 8KW is a big array for an urban setting. The max our DNO would allow was 5KW.

I didn't realise the DNO had any say in array size. The G99 application is just for the feed in limit isn't it?

There's a number of properties around with similar sized arrays anyway.

[8bit]

Thanks for the clarifications around the DNO.

clockworks said:

With an EV, and an EV tarrif, have a look at going for battery only, no solar.

A big enough battery, charged overnight on 8p electric, will more than halve your electricity bill.

Next step, replace gas with a heat pump. Combined with a bigger battery, heat your house on 8p electricity (at 350% efficiency), a third of the cost of gas.

There are plenty of options unlocked by having an EV tarrif. Explore the potential savings and up-front costs of all the options before spending any money.

That's really interesting, thanks - I'll look into that. I had started thinking about a heat pump but was under the impression they only really reduced costs if your home is fully insulated in the first place? Ours is all lath and plaster walls with little to no cavity insulation so not exactly energy efficient in the first place.

[gangzoom]

kambites said:

gangzoom said:

Not sure how built up the area is, 8KW is a big array for an urban setting. The max our DNO would allow was 5KW.

I didn't realise the DNO had any say in array size. The G99 application is just for the feed in limit isn't it?

There's a number of properties around with similar sized arrays anyway.

The DNO I believe care about the grid not being overloaded with export when it's a sunny day and every house is exporting back via solar. I'm not sure of the exact legal details I'm sure you can fit what ever array you want, but I believe the minute it's connected to any kind system that interacts with the grid you will need DNO approval.

Your installer should sort all of this out though, we initially wanted 6KW but had to downgrade to 5KW. We had no interaction with the DNO, the installer did all the paper work and than supplied all the relevant certificates.

[OutInTheShed]

kambites said:

gangzoom said:

Not sure how built up the area is, 8KW is a big array for an urban setting. The max our DNO would allow was 5KW.

I didn't realise the DNO had any say in array size. The G99 application is just for the feed in limit isn't it?

There's a number of properties around with similar sized arrays anyway.

I think the DNO can dictate the max inverter capacity connected to the grid.

So you can have more panels but peak power will be clipped to whatever your inverter limits at.
Which means you could have loads of panels pointing east and west and hit your G99 limit for long periods.

You're not supposed to generate 5kW, consume 1kW and export 4kW if your G99 limit is 4kW. AIUI.

[gmaz]

clockworks said:

With an EV, and an EV tarrif, have a look at going for battery only, no solar.

A big enough battery, charged overnight on 8p electric, will more than halve your electricity bill.

Next step, replace gas with a heat pump. Combined with a bigger battery, heat your house on 8p electricity (at 350% efficiency), a third of the cost of gas.

There are plenty of options unlocked by having an EV tarrif. Explore the potential savings and up-front costs of all the options before spending any money.

I don't agree. A 1930's house in Aberdeen is likely to have a large heat loss due to the construction. Heat pumps need a very well insulated house as they run at lower temps than a gas boiler.

Solar and battery is a good option. Get >10kWh battery and charge it during the night using your EV tariff. Export the solar as much as possible.

Get 2 or 3 quotes. An Eleven Energy salt battery may be better suited to North Scotland as they work well in low temps. https://www.elevenenergy.co.uk/#sodium-ion

[clockworks]

gmaz said:

I don't agree. A 1930's house in Aberdeen is likely to have a large heat loss due to the construction. Heat pumps need a very well insulated house as they run at lower temps than a gas boiler.

Solar and battery is a good option. Get >10kWh battery and charge it during the night using your EV tariff. Export the solar as much as possible.

Get 2 or 3 quotes. An Eleven Energy salt battery may be better suited to North Scotland as they work well in low temps. https://www.elevenenergy.co.uk/#sodium-ion

..and I don't agree with your first statement.

Of course, a well-insulated home will be easier and cheaper to heat, whatever the heat source.

That doesn't mean that a badly-insulated house can't be heated with a heatpump, just that it'll be less efficient and cost more than a well-insulated one.
You just need to size the heatpump, radiators, and flow temp to suit the building.

Sure, if your house struggles to keep warm with a big gas boiler running hard at 70 degrees plus, you'll struggle with a heatpump - unless you fit bigger radiators.
There's always the option of a "zero disrupt " installation, where the rad changes are minimised, and a heatpump running at higher temperatures is fitted. 50 or 55 degrees flow is possible, while still getting 300%+ efficiency.
Heatgeek are actively getting into this market - it isn't always just about SCOP.

You can even get heatpumps that will flow at 70 or 80 degrees, easily matching a gas boiler.
Wouldn't make financial sense if you were paying 25p for electricty, as it would cost more than gas.
Using 8p electricity from a battery is a different matter though. Even if the heatpump is only 200% efficient on a really cold day, 8p electricty would be half the running costs of gas.
Careful maths needed to compare the payback time with the upfront cost of the batteries though.


Your second point kind of supports my point that batteries can make more sense than solar on a purely financial basis.
Import from the grid and store at 8p. Export your solar at 12p. No point in consuming your own solar.
What's the payback time on solar if you just export everything at 12p?

For us, 18 panels on an east/West split, zero external shading, Cornwall, would be over 9 years.
That's assuming no maintenance costs, and that the feed-in rate doesn't drop again.

12KWh battery, payback under 3.5 years.
24KW battery, payback around 5.5 years.

Solar can make sense in the long term, but battery pays back far faster - on the right tarrif.

[Byker28i]

gmaz said:

clockworks said:

With an EV, and an EV tarrif, have a look at going for battery only, no solar.

A big enough battery, charged overnight on 8p electric, will more than halve your electricity bill.

Next step, replace gas with a heat pump. Combined with a bigger battery, heat your house on 8p electricity (at 350% efficiency), a third of the cost of gas.

There are plenty of options unlocked by having an EV tarrif. Explore the potential savings and up-front costs of all the options before spending any money.

I don't agree. A 1930's house in Aberdeen is likely to have a large heat loss due to the construction. Heat pumps need a very well insulated house as they run at lower temps than a gas boiler.

Solar and battery is a good option. Get >10kWh battery and charge it during the night using your EV tariff. Export the solar as much as possible.

Get 2 or 3 quotes. An Eleven Energy salt battery may be better suited to North Scotland as they work well in low temps. https://www.elevenenergy.co.uk/#sodium-ion

This. Solar panels are cheap, relative to the rest. Get a big enough battery to run the house for the whole day, charged at the cheap rate. Export any solar generation to offset the cost.
For us, we get 12p export, and if we had an EV/EV tariff it would be 8.5p.


Temps is an important thing to ask, also where the batteries are stored. Ours are in the garage along with the invertor and insulated for the winter, removed for summer.

This was the first battery fitted - note it wont accept a full charge rate (half rated value) until it got over a temp of 20C, so it charged very, very slowly, sometimes never reaching full. Note this is for each 2.5kwh battery




We complained, got them replaced with a later spec battery that had much better charge rate to lower temps.



If you do put kit in the garage, then I'd also suggest linked smoke alarms for garage and house.

[clockworks]

The panels are cheap, it's installation costs that are the killer.
I was quoted £500 per panel, installed. Crazy

[Cheib]

clockworks said:

gmaz said:

I don't agree. A 1930's house in Aberdeen is likely to have a large heat loss due to the construction. Heat pumps need a very well insulated house as they run at lower temps than a gas boiler.

Solar and battery is a good option. Get >10kWh battery and charge it during the night using your EV tariff. Export the solar as much as possible.

Get 2 or 3 quotes. An Eleven Energy salt battery may be better suited to North Scotland as they work well in low temps. https://www.elevenenergy.co.uk/#sodium-ion

..and I don't agree with your first statement.

Of course, a well-insulated home will be easier and cheaper to heat, whatever the heat source.

That doesn't mean that a badly-insulated house can't be heated with a heatpump, just that it'll be less efficient and cost more than a well-insulated one.
You just need to size the heatpump, radiators, and flow temp to suit the building.

Sure, if your house struggles to keep warm with a big gas boiler running hard at 70 degrees plus, you'll struggle with a heatpump - unless you fit bigger radiators.
There's always the option of a "zero disrupt " installation, where the rad changes are minimised, and a heatpump running at higher temperatures is fitted. 50 or 55 degrees flow is possible, while still getting 300%+ efficiency.
Heatgeek are actively getting into this market - it isn't always just about SCOP.

You can even get heatpumps that will flow at 70 or 80 degrees, easily matching a gas boiler.
Wouldn't make financial sense if you were paying 25p for electricty, as it would cost more than gas.
Using 8p electricity from a battery is a different matter though. Even if the heatpump is only 200% efficient on a really cold day, 8p electricty would be half the running costs of gas.
Careful maths needed to compare the payback time with the upfront cost of the batteries though.


Your second point kind of supports my point that batteries can make more sense than solar on a purely financial basis.
Import from the grid and store at 8p. Export your solar at 12p. No point in consuming your own solar.
What's the payback time on solar if you just export everything at 12p?

For us, 18 panels on an east/West split, zero external shading, Cornwall, would be over 9 years.
That's assuming no maintenance costs, and that the feed-in rate doesn't drop again.

12KWh battery, payback under 3.5 years.
24KW battery, payback around 5.5 years.

Solar can make sense in the long term, but battery pays back far faster - on the right tarrif.

150 year old solid brick house. We installed heat pump’s two years ago.

It is possible to get them to work in an only house but it very much depends on the current system as in pipe work and rads and also the thermal mass of the house. We have some pretty deep sold brick internal walls so they are a big positive from a thermal mass perspective. I’d say double glazing also a necessity if you want good running costs.

We went with new rads and pipework but not everybody has to.

[theboss]

OutInTheShed said:

You're not supposed to generate 5kW, consume 1kW and export 4kW if your G99 limit is 4kW. AIUI.

That's exactly how a G99 approval with G100 export limit is designed to work. You can use the extra capacity of the inverter onsite, only exports are curtailed. There's a certification process for G99/100 so they are able to approve devices that have been validated to meet the requirements for export limits (for example it has to be an installer level setting - the end user can't change it)

I have a 25kW inverter with 9kW export limit for example.

[Harpoon]

Following with interest. We live in an early 1800s house (was once a Methodist chapel) with an aging oil boiler & tank. I saw something the other day of an increased government grant for "off-grid" homes to get a heat-pump but need to learn more to understand what the options are and what order you might do things in (assuming you can't afford do everything at once).