Well, where to start.

First, PV’s consume more energy in their manufacture and shipping than they will produce so you aren’t saving the planet at all, you are merely outsourcing the carbon to somewhere else (and it’s probably generated by coal so in fact your making it worse).plus you can only produce the amount per panel as the least performing one in that array (unless you’ve fancy controls) so if you’ve a dud one or one that’s overshadowed then your output drops to that…

Secondly if you construct an air tight well insulated and proportioned building (with whole house MVHR) you can reduce your heating load to <15kWh/m2 per annum (i.e. Passivhaus standard). You could use direct electric heaters for that and still be cheap enough.

Thirdly, battery systems. Hmm, I was staying with a mate on Friday who works for a renewables installer. If he moaned about malfunctioning battery systems once he moaned a dozen times. A figured he used was that powerwalls had a 91% installer return rate. If you’ve a 13kW wall he said you really need an 11kW array for it to work properly… if you use the majority of your electricity ‘on site’ then your battery system isn’t getting charged enough and just won’t work (unless you hand it over to a supplier and that means your internet access too. Don’t forget to check the cost of any electricity you might, on occasion, have to buy in too… ouch!).if you also have a heat pump, seriously don’t bother…

Fourthly south facing big windows, nice, best install a heating and cooling heat pump for summer overheating while you’re at it. Proper insulation and you want to limit solar gain…

There is no one size fits all solution.

First, PV’s consume more energy in their manufacture and shipping than they will produce

that just doesn’t sound right tbh. I googled it, apparently it was true – until 2013:
https://www.theverge.com/2013/4/2/4174204/solar-panels-finally-generate-more-energy-than-they-consume

maybe someone should fire off an email to More or Less and get them to investigate!

In December my nominal 3kW solar panels produce around 90-120kWh (350-400 in Sumer). Given the heating bills reported on threads here many people are consuming 10/20/30 times that. Insulate properly as a priority, until you have the solar panels are mainly window dressing.

Germany had legislation going through to enforce the integration of solar panels into new builds and renovation projects. I don’t know if it’s passed yet.

Homeowner with [long time] solar here:
Batteries need to come down in price a lot before they make sense to me – too little generation in the winter (I get less than £90Kwh/month in Nov/Dec/Jan). The rest of the year though solar is great and I get well over 400Kwh/month from April-Sept.
I wish they were mandatory on new houses – having solar actually makes you think about your power consumption a bit more.

Our system has been in just over three years now and I see similar over Nov/Dec/Jan, Feb onwards and it’s great, well worth the investment.

Regards batteries I’m keeping an eye on v2g (vehicle to grid), when that becomes a thing I’ll seriously look at an ev as a 2nd car for all our local trips and it can be used to power the house over night.

First, PV’s consume more energy in their manufacture and shipping than they will produce so you aren’t saving the planet at all, you are merely outsourcing the carbon to somewhere else (and it’s probably generated by coal so in fact your making it worse).plus you can only produce the amount per panel as the least performing one in that array (unless you’ve fancy controls) so if you’ve a dud one or one that’s overshadowed then your output drops to that…

I know its your job to know these things to a point how ever have researched it prior to putting my hand in my pocket it appears to be based on data from about 10 years ago.

Never mind solar what about wind? OK so I am fairly unusual to have land to site it on and mean wind speed approaching 10ms but anyway, I want to get a wind turbine, say a 20kw one and there’s no support at all. That could power me and all my neighbours with net-zero ongoing emissions for both heat and electric (Assuming they all flipped to electric) but there’s literally zero Gov help, and yet you can get 5k to install an overpriced energy using heat pump…

Hmm, I’ve probably mixed things up with embodied carbon. Based on a CIBSE cyclical economy webinar from last year.

And, I forgot about this, it’s also a higher fire risk (our insurer has issued us guidance on it, along with guidance on the increased risks of EV charging….).

I’m not saying PV doesn’t have its place, but it’s not a panacea.

In December my nominal 3kW solar panels produce around 90-120kWh (350-400 in Sumer). Given the heating bills reported on threads here many people are consuming 10/20/30 times that.

Yes, but where do you live?

Insulate properly as a priority, until you have the solar panels are mainly window dressing.

Some buildings are much more difficult to retro-insulate than others….. it’s just not that simple.

Never mind solar what about wind? OK so I am fairly unusual to have land to site it on and mean wind speed approaching 10ms but anyway, I want to get a wind turbine, say a 20kw one and there’s no support at all.

I thought about doing this about 7 years ago – wish I had!
Can you not get FIT payments for wind….. thought you could.

Planning and building control are acts of parliament so it means any changes have to go through a bonkers long process to get changed. Hence they don’t. Councils have no power to force builders to install solar panels. My in laws just moved into a new house and what I don’t get is the builders don’t even give you the option of having pv fitted. First thing they did, but a lot of the cost could have been saved when the builders were doing the electrics and roof. Just the scaffolding cost a good chunk.

We just seem to be so slow at changing laws in this country. If all new houses had to have pv the price wood plummet.

this, with an enormous side order of “why aren’t all houses built with big windows in a south facing wall that allows solar heating of a large thick north wall”

We built an east facing extension on our house with 4m x 2m sliding doors. The floor has dark porcelain tiles over wet UFH.
On sunny mornings the tiles get warm and heat the room and to an extent the whole house.

it’s also a higher fire risk (our insurer has issued us guidance on it, along with guidance on the increased risks of EV charging….)

Interesting. Neither my car insurer, nor my contents insurer, nor my buildings insurer have mentioned any change in cover from charging our EVs. What is the risk? And how does it come about?

The problem for the builder(which I think was the question) is that the cost of a few solar panels are not going be justified without the extra expense of a hot water tank, and/or a serious increase in price on insulation if the buyer imagines they can use the solar to heat the house.
A whole new system and standard of insulation, at which point the house would probably be better redesigned around it.
House plans are designed to minimise build costs and maximise profit, and the customer is largely clueless about how heat efficiency works, they get upset when the first heating bill comes in but they didn’t read the small print when they signed the purchase agreement.

I was at a window manufacturer today, Upvc is next to go apparently, hence why all new builds are throwing them in.

If a single home puts PV on there is little detrimental effect on the local 230/400V cables in the grid. If a whole housing estate does, the builder will be paying for a bigger grid connection than otherwise.

Might influence them a bit.

The other issue with PVs is that they are intermittent and they produce most electricity when demand is lowest

the intermittency of supply is the biggest issue with both wind turbines and PVs

You can have a theoretical supply of 100% of needs from renewables ( as Scotland is aiming for and now close to) but when its night and not windy you need another form of generation that can be mobilised quickly to fill the gaps – with current tech that needs to be fossil fuel. Nuclear is really best suited to a constant baseload as its difficult to turn it on and off from what I understand – dunno if the latest generation of nuclear can turn on and off more easily( plus all the other issues with nuclear which we have argued about ad infinitum)

tidal which as you probably remember I am a big advocate of is again best for continual baseload

the other option if you want to go for a lot of wind and solar PV is you need a lot of storage of energy. PUmp storage works well but we have only a few hours of storage available in pumped storage – and nothing like enough potential sites to gain the weeks worth of energy storage needed

EV cars could be used for a bit of storage but that risks people only having a half charged battery when they need a full one ( two way connection to the grid with smart charging)

Houses could have batteries but the stuff needed to make batteries is expensive and rare and has its own pollution issues and again its needs to be weeks worth of storage for each house not hours.

Until storage is sorted then its hard to see how a much greater amount of renewables can be used and also that we still need a reserve of fossil fuels

I have high hopes for Hydrogen for this and its been shown to work well on a small scale – but large scale again there are major issues – its expensive and energy intensive to liquefy hydrogen and storing it as gas would need massive tanks.

This is why the idea of solely using renewables to power a county is simply not feasible at the moment or within the sort of timescales needed – certainly in more northern countries – countries with more reliable sunshine and less variation day to night these issues are less

Hence energy efficiency / use reduction on a massive scale is the best thing we can do now – its low tech and the tech exists and reducing energy usage reduces greenhouse gas emissions. Its the only possible solution in the timescales needed

the longer people continue with the myth that lifestyles do not have to change and tech can provide all the answers the worse the situation becomes

anyone want to pick holes in this analysis? Squirellking?

Diversity and interconnection assists spectacularly with wind intermittency – because it’s normally windy somewhere.

So pan-European markets and systems are a benefit to decarbonisation.

Hydrogen is a nice idea, but some significant issues remain.

Consumption reduction is always good – not always popular.

Fourthly south facing big windows, nice, best install a heating and cooling heat pump for summer overheating while you’re at it. Proper insulation and you want to limit solar gain…

I’m somewhat sure that one has been worked out at least three thousand years ago by the ancient greeks.

Passivehaus:

Would adding thermal mass to buildings help?

I get huge solar gain in my flat – its an attic in a large stone built building – the weird thing is I have a big delay on it – the flat is warmest at around 6 – 7 pm – I assume thats the whole building warming up and the heat rising to be caught under the “insulated cap” that is my flat.

Can you not get FIT payments for wind….. thought you could

You can’t get FIT on any new installations now. The scheme is closed.

What tj said. Beyond a certain point wind and solar destabilise the grid. They piggyback on gas to fill in when the wind drops at night. The wind and solar operators don’t pay the costs of having reliable backup though. The consumer does through levies on our Bill’s.

California has this in a big way. Massive solar generation means the grid has to rapidly ramp power up and down every day.

https://www.nuscalepower.com/environment/renewables/the-duck-curve

The SNP 100% renewable plan relies on power transfers from England when the wind drops. It will be far worse once Torness closes.

California has this in a big way. Massive solar generation means the grid has to rapidly ramp power up and down every day.

The American grid is not as interconnected at transmission level as one might hope.
We’re building some more transmission out there, and we already trade diurnally as the sun moves across the various states, but there is work to do.
That said their spread of time zones gives huge potential.

East-west interconnection and solar could compliment each other nicely – and remember we use less energy at night. North-south interconnection assists with connecting high energy harvesting areas with lower ones (round here that’s wind in the north and PV in the south, but global thinking may be needed).

I’m somewhat sure that one has been worked out at least three thousand years ago by the ancient greeks.

And the native Americans (possibly more recently than 3000 years) who used different shading on their buildings (darker on the walls, lighter on the roofs) to vary solar gain through the year.

The SNP 100% renewable plan relies on power transfers from England when the wind drops. It will be far worse once Torness closes.

The original plan was to build two rapid spin up gas generators to have self sufficiency but westminster legislation made that impossible

this, with an enormous side order of “why aren’t all houses built with big windows in a south facing wall that allows solar heating of a large thick north wall”

one of the best and worst features of my house is the solar gain.

In winter the south facing downstairs living areas heat up nicely from it due to a big ass window

In summer the large eaves overhang keeps the high sun out the living space windows so it can be 20-23 out side and 18 inside. how ever we sleep in the roof space with a dormer that doesnt get shelter from the sun – the attic and bedrooms can be 25 degrees and dont cool down even with the windows open . The solar panels have removed a large amount of direct sun light contacting the south facing roof at least.

UK house builders just build to a cost which achieves compliance with regs. If they do 100 houses of the same type I’m pretty sure that they only need to to an air test on one of them, so that’s the one which will be built properly. Rather than implementing things like the upcoming ban on gas boilers in new builds the Gov. should just put a heavier penalty in the SAP calc on a lack of renewables (they already do this in wales for new commercial builds, not sure about domestic) this would then force people to look at the best energy scheme for each type of building.

Carbon taxation would change a lot of this. If energy becomes more expensive and insulation less then it becomes more cost efficient to insulate

to me carbon taxation ( changeover taking 10 – 20 years) is the best way to go about reducing energy usage

Good point, i agree with that TJ. I’d like to think that one day the fuel used in international shipping is taxed commensurate to the pollution it produces & the world can go back to producing the stuff it needs in it’s own country. I’m pretty sure we used to make TV’s & audio equipment in the UK not so long ago.

The roof overhang diagram up there is for somewhere 35°N, Birmingham is 52° IIRC. It has a difference between Summer and Winter of 50° which is a slight exageration. The difference between solstices is 47° based on the tropics of Capricorn and Cancer. having lived in a building like that I’m not convinced. It can still be cold in June and hot in October. Temperature lags the seasonal changes in sun height.

A better solution IMO is shutters, you can keep the sun out or let it in any time you want. My shutters are Persian which lets some light in and allows air flow in Summer. I’ve added mosquito nets to keep insects out. I add boards in Winter so they add insulation when closed at night.

to me carbon taxation ( changeover taking 10 – 20 years) is the best way to go about reducing energy usage

That’s fine if you don’t worry about how equitable your tax system is. Energy taxes disproportionately affect the poor. If you do have an energy tax it needs to be (highly) progressive and contain protections for the poorest. That can partly be achieved with tax credits or energy cheques for the poorest. Making an energy tax progressive means taxing things consumed more by the rich. For example flights, you’ll note that the least taxed fuel is aviation fuel. Go figure.

. Energy taxes disproportionately affect the poor

Only if you design it like this. Government could easily create a progressive carbon tax, but choose not to.

The whole tax systems needs inverting – High rate tax payers should only be able to claim tax brakes at the lower rate and visa-versa. The same should apply to carbon taxation.

This would be REAL “Leveling Up”.

to me carbon taxation ( changeover taking 10 – 20 years) is the best way to go about reducing energy usage

Nothing new on this one, the difficulty is in the details of the implementation. Which is always the issue tbh!

@tjagain

The original plan was to build two rapid spin up gas generators to have self sufficiency but westminster legislation made that impossible

Interesting. A new one on me. Any link? The only things I’ve seen the SNP do is ban fracking. I thought they believed gas was bad?

“the Scottish Government has concluded that fracking is incompatible with its climate change commitments.”

What is the SNP policy on fracking?

Thanks for all the replies to this. I thought it would a reasonably simple answer but I’m bamboozled by some of the jargon! 🙂

IRC – it was a maybe decade or so ago. I read the proposal at the time. I don’t think it ever made it any further than discussion papers but not sure. Nothing obvious on the net now but I am sure about this

I did find mention of one plant being given consent in 2011 in hansard

anyone want to pick holes in this analysis?

Just the obvious stuff, heating the average house with electricity is massively expensive(unless it is seriously insulated which most are not) and subsequently the amount of electricity we would need is beyond our current ability to produce by a very long way.

There is no escaping the fact that we don’t have a cost effective alternative to gas that can heat houses designed only to gas standard.

Surely the answer is woodburners and a unicorn? After all, every true Brit is due a free horny horse now brexit got done, aren’t they?

In a serious note, what tj said, progressive carbon tax, proper grants for insulating poor performing buildings. If you want everyone to insulate and stop burning stuff, it has to be made cost effective for them to make that choice.

Sorry to resurrect this thread.
What are people’s views on having greater than the standard 4kWh install?
Is it worth it for increasing year round supply.
Just had a quote for 8.2kWh panels and a tesla battery that came out at 21k installed