Solar Panels

[Woodchopper]

What I’m getting from reading all this is that it’s much safer to buy into a scheme where someone else installs and operates the panels somewhere else, and you just get the return (and the cosy warm glow of doing your bit for decarbonisation).

That would result in lower risk, but might also give you a lower return on investment. The advantage of using your own roof is that you already own or are paying for the land and cable connection to the electricity grid. So for those items there isn't an increased marginal cost for installing solar power, and the cells might even increase the value of your land.

As we've discussed before, while solar cells get ever cheaper there are still significant cost in obtaining land and installing the cells (of which a connection to the grid can be expensive). Investing in a large solar farm might mean that you cover the costs of things that you'd have got for free at home.

[Edited syntax, fixed errors]

[lpm]

But the labour cost of the home install is huge, per kWh.

No home install would ever beat a co-op, in a free market for electricity. However it is a rigged market. This has led to bad economics - thousands of individual installs at high cost.

[Grumble]

But the labour cost of the home install is huge, per kWh.

No home install would ever beat a co-op, in a free market for electricity. However it is a rigged market. This has led to bad economics - thousands of individual installs at high cost.

Part of the issue is that home installs don’t need things like new interconnections, which can increase cost and delay (and delay is a cost)

[bjn]

AIUI, the significant cost is just getting people up on your roof. If people are already on your roof (eg to make it in the first place, or to fix it), the marginal cost of installing panels would be less than doing it as a one off. Especially when the building is being built as one of many similar houses.

FWIW, Chinese wholesale prices for solar panels is now 9.5 cents/W. ie: USD $95/kW. Panels are the cheap bit now, rest of system costs (labour, inverters, cabling etc…) will dominate going forward.

[bjn]

But the labour cost of the home install is huge, per kWh.

No home install would ever beat a co-op, in a free market for electricity. However it is a rigged market. This has led to bad economics - thousands of individual installs at high cost.

Part of the issue is that home installs don’t need things like new interconnections, which can increase cost and delay (and delay is a cost)

And consuming your own kWhs “behind the ’meter” means not paying for all sorts of system costs bundled into retail prices of a kWh.

[lpm]

Either

1. Put 7 panels on 10,000 individual roofs, requiring 10,000 lots of labour

2. Put 70,000 panels in a field, with far lower labour costs, but then lose 10% (?) of generation in transmission to 10,000 homes

It should be that 2 is far superior economically. The fact that 1 is competitive shows something has gone wrong. We pay far, far more in £ for transmission loses than justified.

Remember that homes with panels on their roofs still need to pay identical connection costs and grid services costs as non-solar homes.

[dyqik]

Either

1. Put 7 panels on 10,000 individual houses' roofs, requiring 3,000-10,000 lots of labour.

2. Buy a field with planning permission for solar arrays (but not for houses), put 70,000 panels in a field, with lower labour costs, but then lose 10% (?) of generation in transmission to 10,000 homes and have to pay transmission costs on the power generated.

There's no reason to assume that 2 is far superior economically. The fact that 1 is competitive shows that the cost of land with planning permission is high, and that transmission costs are a substantial portion of energy costs.

Remember that homes with panels on their roofs will already pay the identical connection costs and grid services costs as non-solar homes, and so the marginal costs of installing panels on homes that are having roof work done anyway (new build or repair) is minimal.

FTFY.

[lpm]

Poor quality land is very cheap. For Ripple 3 we're renting it on a long lease, the owner will presumably make a similar return vs other potential uses.

Planning permission is slow but not costly.

[dyqik]

Poor quality land is very cheap. For Ripple 3 we're renting it on a long lease, the owner will presumably make a similar return vs other potential uses.

Planning permission is slow but not costly.

Time is money.

The cost of distribution is a major factor that you've ignored here. Obviously I'm in the US with different economics around electricity supply, but more than half the cost of my 100% renewable electricity is the delivery charges, charged per kWh flowing into the house. For home installed solar panels, you don't pay that, but for co-op schemes, you will.

[lpm]

But delivery charges should be in line with transmission losses.

Everything else is fixed cost, not variable.

[dyqik]

But delivery charges should be in line with transmission losses.

No, transmission losses are included in the cost of generation. Delivery charges are the charges for maintenance and upkeep on the wires connecting your house to the generation site, the costs of billing, etc.

[lpm]

...which are all fixed costs, not variable.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

[IvanV]

...which are all fixed costs, not variable.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

You are exactly right, this is the big issue. Exactly as you say, a lot of system costs are spread per unit for households, meaning that domestic households mostly pay 15p-20p per unit. A more economic set of charges would be if we all paid the wholesale price, currently something like 8p per unit on average, and a much larger fixed charge.

But there are some good reasons for the current way of doing it. Large fixed charges are not very friendly to the less well off. We don't pay time of day tariffs, and probably it helps keep peak demand down if we pay something nearer peak charges rather than average charges.

But utilities in some countries, especially sunnier countries like Spain and Australia, have made a lot of noise about the loss of income towards system costs that occurs when people put up their own PV panels. In Spain, the utility suggested that domestic customers should have to pay a system cost per unit, whether they import that electricity or generate it themselves, unless they disconnected from the network. They have suggested we should think of it as a back-up or insurance charge - a price for ensuring that electricity will be supplied to us from the grid when we don't have our own. Or maybe those who install PV panels should be put on a tariff with a larger fixed cost and lower unit charge.

Roofs are a good place for solar panels, in the sense that they don't occupy any land when you put them there. But the installation costs are high on existing dwellings. Maybe at the moment the market is not excessively distorted given that issue. In the longer run, at least in Britain, the implicit subsidy to domestic solar panels through avoidance of the system costs might need adjusting. In sunnier places, the issue might be already here.

[Gfamily]

...which are all fixed costs, not variable.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

Not sure where your figures are from, but I think it's currently (no pun intended) 7 or 8pkWh for domestic FIT.
https://renewable.exchange/blog/what-is ... ort-tariff

[dyqik]

...which are all fixed costs, not variable.

For me they are charged per kWh consumed. They are billed as variable costs. This is likely true in the UK as well, with the costs included in the electricity price you pay per unit. Fixed charges would have to be about the same as the average variable charges for it to be flat rate billed.

The calculations are detailed here: https://en.m.wikipedia.org/wiki/Electri ... _in_the_UK

Which makes sense. Heavy users are the ones that drive heavier grid infrastructure, and higher maintenance costs.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

There are significantly more differences than the transmission loss. Transmitting more power longer distances requires more lines, and more maintenance on lines. Requiring higher uptime on lines makes maintenance more expensive. That's all determined by the grid loading and how far electricity is coming from as sources and loads change.

[dyqik]

...which are all fixed costs, not variable.

For me they are (ETA partly) charged per kWh consumed. They are billed as variable costs. This is likely true in the UK as well, with the costs included in the electricity price you pay per unit. Fixed charges would have to be about the same as the average variable charges for it to be flat rate billed.

The calculations are detailed here: https://en.m.wikipedia.org/wiki/Electri ... _in_the_UK

Which makes sense. Heavy users are the ones that drive heavier grid infrastructure, and higher maintenance costs.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

There are significantly more differences than the transmission loss. Transmitting more power longer distances requires more lines, and more maintenance on lines. Requiring higher uptime on lines makes maintenance more expensive. That's all determined by the grid loading and how far electricity is coming from as sources and loads change.

Looking at some UK tariffs, the standing charges seem to be around the same price as 2-3 units of electricity per day - about £15-20 a month. Which is about the same as for me. The per unit distribution charges I pay are about 60% of my unit costs - about 8 times the standing charge.

[IvanV]

...which are all fixed costs, not variable.

Every home has to pay for those fixed costs, whether solar or non solar.

Economics is about the marginal cost, i.e., the variable cost. There is clearly something wrong - economically - when a far away solar panel earns 4p per kWh while a solar panel a few meters away on the roof earns 15p per kWh, given the only significant variable cost is the 10% transmission loss.

Not sure where your figures are from, but I think it's currently (no pun intended) 7 or 8pkWh for domestic FIT.
https://renewable.exchange/blog/what-is ... ort-tariff

lpm's 15p is what you save when you consume a unit and avoid buying it from the grid. With a decent sized battery, which have got a lot cheaper, you can use a high proportion of your output. Home PV systems increasingly have batteries. So that 15p per unit saving is a large amount of what is driving people, like me, to go solar. In fact my present rate is something like 17p.

But, would you believe, Octopus will pay you 15p a unit for your exported solar energy. That's what they are paying me. I don't know how or why, it seems far too much.

Octopus also have a system for domestic customers where you can fill your battery from the grid at night or whenever electricity is cheap, if you aren't filling it from your solar, and then export it back when it is more expensive. My inverter isn't clever enough to do that, but my mate's is, and he gets that extra income from his solar/battery set up.

So although the over-generous government mandated FITs are no longer available to new customers, it is amazing what the free market will currently give you.

I put in solar because at current electricity prices it was a no-brainer. In fact with a 15p export payment, arguably I didn't really need to bother with batteries, but I never expected such generosity. And I do recognise it is an artefact of tariffs that it is worthwhile doing this.

As has been said, the labour cost of installing solar panels in a field is much less. But then it takes up a field. And a lot of people are complaining about ugly solar farms in fields near them. There is the land cost, but with agricultural land around £28,000 a hectare, that's unlikely to change the efficiency argument. A solar farm I know in Somerset, owned by a beef farmer, put their panels on tall holders so animals could graze underneath. Clearly the productivity of the land is reduced by the shading, but I think the grazing was as much about avoiding the cost of vegetation control.

That's the average cost of arable farmland. In theory you should select poor farmland. But in practice poor farmland generally is in more scenic areas of poor access. So probably it doesn't go on low productivity farmland. I have previously done calculations on this forum of how much land area you need for solar to get various amounts of energy, and it is a lot more efficient in land usage than biomass.

Another mate of mine has their solar panels in their garden rather than on their roof, and installed it themselves. They have about 25 panels vs my 10. So that was very efficient in terms of installation cost, and it's her garden. I don't know how selling the house later will be, but it's her house.

[Grumble]

I have a share in Ripple 2, the wind farm at Kirk Hill, which nominally covers all my usage right now. But I expect my electricity usage to go up substantially when I get an EV (currently on order) and then further at some point in the future when I will probably get a heat pump. So some form of additional power generation will be good for me. My roof isn’t brilliant for solar, but it’s not shaded so maybe it would be worth it, especially with batteries. Clearly I need to spend some time researching this, or at least researching my local installers.

[Sciolus]

But, would you believe, Octopus will pay you 15p a unit for your exported solar energy. That's what they are paying me. I don't know how or why, it seems far too much.

That is only if you also buy your electricity and gas from them as well. Presumably they consider the extra recruitment of paying customers is worth what they pay to buy energy. And plenty of other companies provide derisory SEG rates, as little as 1 p/kWh.

[bjn]

I have a share in Ripple 2, the wind farm at Kirk Hill, which nominally covers all my usage right now. But I expect my electricity usage to go up substantially when I get an EV (currently on order) and then further at some point in the future when I will probably get a heat pump. So some form of additional power generation will be good for me. My roof isn’t brilliant for solar, but it’s not shaded so maybe it would be worth it, especially with batteries. Clearly I need to spend some time researching this, or at least researching my local installers.

I’m a member of Kirk Hill as well, I believe LMP is too. I’m contemplating heat pumps when the boiler eventually, but should buy more wind power to cover that as opposed to solar, because winter and all that.

That said I’ve heard other accounts like Ivans, where solar + battery setups are making money not just by displacing grid supply, but by providing generation and smoothing services, and have thought about installing for that. There’s value in putting generation and batteries behind the transformer, as well as behind the meter, as it takes peak strain off the trunk lines

South Australia is big on Virtual Power Plants, where they aggregate and control distributed rooftop battery and solar. Rooftop solar now provides a significant proportion of the power to their grid, as in all of it. This month they hit 101% of their demand purely from panels on roofs, they exported the excess to Victoria, along with a chunk of wind.

[discovolante]

But, would you believe, Octopus will pay you 15p a unit for your exported solar energy. That's what they are paying me. I don't know how or why, it seems far too much.

That is only if you also buy your electricity and gas from them as well. Presumably they consider the extra recruitment of paying customers is worth what they pay to buy energy. And plenty of other companies provide derisory SEG rates, as little as 1 p/kWh.

Cleaning Up's latest episode is a fairly long and detailed interview with Greg Jackson, which I found quite interesting: https://www.cleaningup.live/the-kraken- ... g-jackson/

[IvanV]

My roof isn’t brilliant for solar, but it’s not shaded so maybe it would be worth it, especially with batteries.

In what sense isn't it brilliant?

E & W facing slopes are actually rather good, probably better than a house with NS facing slopes. You get worthwhile production off both slopes, even if the production per panel is only 76-73% of a S-facing panel, at 30-40 degree roof inclination (flatter the better in this case). You can fit twice the panels, giving you about 50% more production in total, and your output is less peaked, giving you more electricity at times of day when it's more valuable. With a NSEW pyramid type roof, you have 3 useful slopes, assuming each slope is sufficiently extensive. Perhaps a more annoying orientation might be something like SE/NW or SW/NE. Though even then you can get 60-65% of S-facing production at 30-40 degree inclination from a NE/NW facing slope, so it may still be worthwhile fitting both slopes. It is steep roof inclinations that really reduce the production, because you get much more shading of the panels that are N of E and W with steeper roofs.

There's a roof orientation and tilt production graph here here, which might be useful. By random good fortune, mine is less than 2 degrees off perfect EW.

What can be more tricky is complex roof-shapes with lots of interruptions, dormer windows, roof lights, etc. As mine have. On my E slope, there is only easy space for 4 panels, because of such interruptions. Just take the dormered porch away, and there would have been space for at least 8, even with the two bedroom dormers above.

There was no useful space at all on the sloping part of my W roof at all, at least not for the dimension of panel they were fitting. The flat roof extension cuts short the comparable piece of roof where they went on the E slope. So my W panels are all on the flat roof, which is annoying because of the refelting issue. There was fortunately space for 6 panels on the flat roof, despite the 4 roof lights, without which there would have been space for 10-12 there. I also have a S-facing garage roof which would have been good for 3 or 4 panels. But the costs of dealing with the wiring issues, given the garage is a separate building, would have been too much for that modest number of panels.

[dyqik]

But, would you believe, Octopus will pay you 15p a unit for your exported solar energy. That's what they are paying me. I don't know how or why, it seems far too much.

That is only if you also buy your electricity and gas from them as well. Presumably they consider the extra recruitment of paying customers is worth what they pay to buy energy. And plenty of other companies provide derisory SEG rates, as little as 1 p/kWh.

Maybe they have more in the way of commercial and industrial users, so they can use excess domestic middle-of-the-work-day solar for commercial uses rather than buying it from other suppliers. Or maybe I have that backwards and they make a bigger profit by selling more of the domestic excess solar because they don't need it for commercial customers - it's early and I haven't had coffee.

[Grumble]

My roof isn’t brilliant for solar, but it’s not shaded so maybe it would be worth it, especially with batteries.

In what sense isn't it brilliant?

E & W facing slopes are actually rather good, probably better than a house with NS facing slopes. You get worthwhile production off both slopes, even if the production per panel is only 76-73% of a S-facing panel, at 30-40 degree roof inclination (flatter the better in this case). You can fit twice the panels, giving you about 50% more production in total, and your output is less peaked, giving you more electricity at times of day when it's more valuable. With a NSEW pyramid type roof, you have 3 useful slopes, assuming each slope is sufficiently extensive. Perhaps a more annoying orientation might be something like SE/NW or SW/NE. Though even then you can get 60-65% of S-facing production at 30-40 degree inclination from a NE/NW facing slope, so it may still be worthwhile fitting both slopes. It is steep roof inclinations that really reduce the production, because you get much more shading of the panels that are N of E and W with steeper roofs.

There's a roof orientation and tilt production graph here here, which might be useful. By random good fortune, mine is less than 2 degrees off perfect EW.

What can be more tricky is complex roof-shapes with lots of interruptions, dormer windows, roof lights, etc. As mine have. On my E slope, there is only easy space for 4 panels, because of such interruptions. Just take the dormered porch away, and there would have been space for at least 8, even with the two bedroom dormers above.

There was no useful space at all on the sloping part of my W roof at all, at least not for the dimension of panel they were fitting. The flat roof extension cuts short the comparable piece of roof where they went on the E slope. So my W panels are all on the flat roof, which is annoying because of the refelting issue. There was fortunately space for 6 panels on the flat roof, despite the 4 roof lights, without which there would have been space for 10-12 there. I also have a S-facing garage roof which would have been good for 3 or 4 panels. But the costs of dealing with the wiring issues, given the garage is a separate building, would have been too much for that modest number of panels.

My roof is hipped, so there isn’t much space up there to fit many panels. It’s a semi, so one side of the pyramid isn’t ours for a start. The two suitable sides would be SSW/WNW. Might be able to fit 5 SSW and 3 WNW.

[IvanV]

My roof isn’t brilliant for solar, but it’s not shaded so maybe it would be worth it, especially with batteries.

In what sense isn't it brilliant...

My roof is hipped, so there isn’t much space up there to fit many panels. It’s a semi, so one side of the pyramid isn’t ours for a start. The two suitable sides would be SSW/WNW. Might be able to fit 5 SSW and 3 WNW.

Yes, small is a widespread problem. I should have thought of that. Maybe batteries and panels being cheaper these days, and higher electricity prices, that's making smaller fittings more economic. Though the 10 panels I have was the smallest fitting the installer I used would contemplate, but it is a common fitting size, what the average 3 bed house can fit.

You do occasionally see panels fitted on brackets on vertical parts of wall. So that could be an option to extend the fitment if you have sufficiently large window-free areas of wall on the SSW side of the house. Vertical is simplest to mount, but you can increase the collection power with brackets that tilt them out a bit. These would have differential shading (from your house itself) from the panels on the roof above. So it might result in a requirement for optimisers if you can't wire them in a separate run from those on the roof above. Similarly the panels in the two areas of roof would have differential shading, and should be wired in separate runs, or you'd need optimisers.