Solar PV - economics?

[mikeiow]

DonkeyApple said:

Yes. Thanks. Calcs today obviously don't include FIT as you point out. How much can you sell at 43p as the obvious arbitrage is to sell all the solar and then load the battery overnight with cheap Grid. Even only being able to sell the excess at a near market rate skews the numbers hugely in favour.

Can you calculate the payback duration without FIT?

In my situation I'm still hearing via gas so the electricity usage is too low for any self generation or storage set up to be remotely viable against just putting the money in the markets. The clear pivot point takes place when the gas boiler can't be replaced and the house has to go pure electric and that is some years away. That will also coincide with EV cars being in the garage.

Maybe you misunderstand FIT
They pays us for ALL we generate, REGARDLESS of whether we use it or not...
We then get a smaller number for 50% of that, which is what they assume we export (hint - we try not to....)

Our heating is also gas. No plans to change that.
Indeed, last extension a few years ago included gas 'wet' ufh, on the basis that we did try electric underfloor mats before and they increased electric usage by 6x (seriously!) and didn't add a huge amount of heat.
In defence of electric ufh, this was to a regular concrete ground floor with no special insulation (retrofitting electric ufh is a recipe for disaster, IMHO).

The EV is fairly separate from most of this, other than we have a Zappi chargepoint that will use excess solar when it exceeds 1.2kWh....otherwise we just charge that overnight on cheap rate....EVs are way too big to sensibly use battery storage to fill from.....added to which our battery inverter only chucks it out up to about 3.2kWh: the car will such from the grid up to 7.

Edited by mikeiow on Monday 5th June 15:59

[mikeiow]

Penny Whistle said:

As has been stated, everyone's case will be different to everyone else's. One factor which does not appear in recent discussions here is the introduction of an EV into the mix.

I have an EV with 200+ mile range, which at this time of year I charge almost exclusively from excess solar. I do not yet have an export MPAN so cannot get paid for exporting energy to the grid, so no lost income is caused by filling the car. Only on (rare) 200-mile journeys do I ever use a public charger, while I also occasionally have to charge the car from the grid at home (due to poor planning on my part). My overall cost per mile since buying the car 21 months ago is 3.3p/mile, compared with 15-25p/mile for my previous daily drivers. The cost of buying the car was marginally more than a similar ICE car, while servicing costs are a lot lower. Factoring that into the payback period of my PV panels makes a huge difference to my payback period.

Not convinced EV usage has a very large part to play in any Solar PV (or indeed home battery) equation. Some, but not a lot.

Our Kona has a 64kWh battery. On a REALLY bright day, we might generate 24+kWh from solar....but of course some of that is used. I think the most I have seen go to our car is 10kW. It is pretty rare (& the excess, certainly for our Zappi, needs to be 1.2kW, sustained....so a cloud can trip the feed and make it pause another 30 seconds!).
From late autumn to spring, it might never happen!

Te reality, to me, is to fill your EV at the cheap-rate energy you can get - for us, 4 hours on Octopus GO between 00:30-04:30. If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....


Roll on more cars that can act as battery banks. Kind of coming - Leaf can be used today - but in a few years it will be more widespread, I predict.
Of course, that will be a whole new ball game of challenges to manage! Am I travelling, can I suck power form my car-battery, etc!

[Jambo85]

mikeiow said:

DonkeyApple said:

Yes. Thanks. Calcs today obviously don't include FIT as you point out. How much can you sell at 43p as the obvious arbitrage is to sell all the solar and then load the battery overnight with cheap Grid. Even only being able to sell the excess at a near market rate skews the numbers hugely in favour.

Can you calculate the payback duration without FIT?

In my situation I'm still hearing via gas so the electricity usage is too low for any self generation or storage set up to be remotely viable against just putting the money in the markets. The clear pivot point takes place when the gas boiler can't be replaced and the house has to go pure electric and that is some years away. That will also coincide with EV cars being in the garage.

Maybe you misunderstand FIT
They pays us for ALL we generate, REGARDLESS of whether we use it or not...
We then get a smaller number for 50% of that, which is what they assume we export (hint - we try not to....)

Our heating is also gas. No plans to change that.
Indeed, last extension a few years ago included gas 'wet' ufh, on the basis that we did try electric underfloor mats before and they increased electric usage by 6x (seriously!) and didn't add a huge amount of heat.
In defence of electric ufh, this was to a regular concrete ground floor with no special insulation (retrofitting electric ufh is a recipe for disaster, IMHO).

The EV is fairly separate from most of this, other than we have a Zappi chargepoint that will use excess solar when it exceeds 1.2kWh....otherwise we just charge that overnight on cheap rate....EVs are way too big to sensibly use battery storage to fill from.....added to which our battery inverter only chucks it out up to about 3.2kWh: the car will such from the grid up to 7.

For bonus points have you got an old meter that goes backwards so in addition to all of the above you get a free unit in winter for each one you export in summer?

[dmsims]

Ohme chargers are faultless, plug in any time after 5pm and off it goes (JLR is the usual st show!)

All leccy consumed is then at the cheap rate and if throttle the car charging ....................

mikeiow said:

If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....

[mikeiow]

Jambo85 said:

For bonus points have you got an old meter that goes backwards so in addition to all of the above you get a free unit in winter for each one you export in summer?

Heh heh heh!
Sadly no....but if we had, we wouldn't have been allowed on Octopus GO (formerly GO Faster!)....

dmsims said:

Ohme chargers are faultless, plug in any time after 5pm and off it goes (JLR is the usual st show!)

All leccy consumed is then at the cheap rate and if throttle the car charging ....................

mikeiow said:

If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....

Not quite sure I can see what you're saying....that Ohme works well with Octopus IO, but that JLR causes grief?

If you have a home battery, I believe the tricky bit is ensuring your battery isn't drained when IO kicks in to start "cheap charging".....something I think that needs a little kludgery with Home Assistant (or similar).
I've decided my days of trying to be clever with tech are behind me.....I like a simple solution, even if it isn't quite as good as it *potentially* could be

[Penny Whistle]

mikeiow said:

Penny Whistle said:

As has been stated, everyone's case will be different to everyone else's. One factor which does not appear in recent discussions here is the introduction of an EV into the mix.

I have an EV with 200+ mile range, which at this time of year I charge almost exclusively from excess solar. I do not yet have an export MPAN so cannot get paid for exporting energy to the grid, so no lost income is caused by filling the car. Only on (rare) 200-mile journeys do I ever use a public charger, while I also occasionally have to charge the car from the grid at home (due to poor planning on my part). My overall cost per mile since buying the car 21 months ago is 3.3p/mile, compared with 15-25p/mile for my previous daily drivers. The cost of buying the car was marginally more than a similar ICE car, while servicing costs are a lot lower. Factoring that into the payback period of my PV panels makes a huge difference to my payback period.

Not convinced EV usage has a very large part to play in any Solar PV (or indeed home battery) equation. Some, but not a lot.

Our Kona has a 64kWh battery. On a REALLY bright day, we might generate 24+kWh from solar....but of course some of that is used. I think the most I have seen go to our car is 10kW. It is pretty rare (& the excess, certainly for our Zappi, needs to be 1.2kW, sustained....so a cloud can trip the feed and make it pause another 30 seconds!).
From late autumn to spring, it might never happen!

Te reality, to me, is to fill your EV at the cheap-rate energy you can get - for us, 4 hours on Octopus GO between 00:30-04:30. If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....


Roll on more cars that can act as battery banks. Kind of coming - Leaf can be used today - but in a few years it will be more widespread, I predict.
Of course, that will be a whole new ball game of challenges to manage! Am I travelling, can I suck power form my car-battery, etc!

EV usage certainly has a large part to play for me, as every mile is free at this time of year; pretty much since the beginning of February, in fact. I do also have an over-sized PV array (13.3kWp) so exported 33.1kWh yesterday ! Yes I am desperately trying to get an export MPAN so I can get paid for that. My Hypervolt on SuperEco charges the car as long as there is 1.4kW spare - I think that is the industry standard.

[86]

Penny Whistle said:

mikeiow said:

Penny Whistle said:

As has been stated, everyone's case will be different to everyone else's. One factor which does not appear in recent discussions here is the introduction of an EV into the mix.

I have an EV with 200+ mile range, which at this time of year I charge almost exclusively from excess solar. I do not yet have an export MPAN so cannot get paid for exporting energy to the grid, so no lost income is caused by filling the car. Only on (rare) 200-mile journeys do I ever use a public charger, while I also occasionally have to charge the car from the grid at home (due to poor planning on my part). My overall cost per mile since buying the car 21 months ago is 3.3p/mile, compared with 15-25p/mile for my previous daily drivers. The cost of buying the car was marginally more than a similar ICE car, while servicing costs are a lot lower. Factoring that into the payback period of my PV panels makes a huge difference to my payback period.

Not convinced EV usage has a very large part to play in any Solar PV (or indeed home battery) equation. Some, but not a lot.

Our Kona has a 64kWh battery. On a REALLY bright day, we might generate 24+kWh from solar....but of course some of that is used. I think the most I have seen go to our car is 10kW. It is pretty rare (& the excess, certainly for our Zappi, needs to be 1.2kW, sustained....so a cloud can trip the feed and make it pause another 30 seconds!).
From late autumn to spring, it might never happen!

Te reality, to me, is to fill your EV at the cheap-rate energy you can get - for us, 4 hours on Octopus GO between 00:30-04:30. If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....


Roll on more cars that can act as battery banks. Kind of coming - Leaf can be used today - but in a few years it will be more widespread, I predict.
Of course, that will be a whole new ball game of challenges to manage! Am I travelling, can I suck power form my car-battery, etc!

EV usage certainly has a large part to play for me, as every mile is free at this time of year; pretty much since the beginning of February, in fact. I do also have an over-sized PV array (13.3kWp) so exported 33.1kWh yesterday ! Yes I am desperately trying to get an export MPAN so I can get paid for that. My Hypervolt on SuperEco charges the car as long as there is 1.4kW spare - I think that is the industry standard.

Also run an EV which I charge for free in summer

[mikeiow]

86 said:

Penny Whistle said:

mikeiow said:

Penny Whistle said:

As has been stated, everyone's case will be different to everyone else's. One factor which does not appear in recent discussions here is the introduction of an EV into the mix.

I have an EV with 200+ mile range, which at this time of year I charge almost exclusively from excess solar. I do not yet have an export MPAN so cannot get paid for exporting energy to the grid, so no lost income is caused by filling the car. Only on (rare) 200-mile journeys do I ever use a public charger, while I also occasionally have to charge the car from the grid at home (due to poor planning on my part). My overall cost per mile since buying the car 21 months ago is 3.3p/mile, compared with 15-25p/mile for my previous daily drivers. The cost of buying the car was marginally more than a similar ICE car, while servicing costs are a lot lower. Factoring that into the payback period of my PV panels makes a huge difference to my payback period.

Not convinced EV usage has a very large part to play in any Solar PV (or indeed home battery) equation. Some, but not a lot.

Our Kona has a 64kWh battery. On a REALLY bright day, we might generate 24+kWh from solar....but of course some of that is used. I think the most I have seen go to our car is 10kW. It is pretty rare (& the excess, certainly for our Zappi, needs to be 1.2kW, sustained....so a cloud can trip the feed and make it pause another 30 seconds!).
From late autumn to spring, it might never happen!

Te reality, to me, is to fill your EV at the cheap-rate energy you can get - for us, 4 hours on Octopus GO between 00:30-04:30. If you have a suitable car or chargepoint (ours are not!), you can get 6 hours with Intelligent Octopus, although even managing that looks a little hairy judging from things I read....


Roll on more cars that can act as battery banks. Kind of coming - Leaf can be used today - but in a few years it will be more widespread, I predict.
Of course, that will be a whole new ball game of challenges to manage! Am I travelling, can I suck power form my car-battery, etc!

EV usage certainly has a large part to play for me, as every mile is free at this time of year; pretty much since the beginning of February, in fact. I do also have an over-sized PV array (13.3kWp) so exported 33.1kWh yesterday ! Yes I am desperately trying to get an export MPAN so I can get paid for that. My Hypervolt on SuperEco charges the car as long as there is 1.4kW spare - I think that is the industry standard.

Also run an EV which I charge for free in summer

Ah, you have industrial scale solar arrays….sure, that will help fill the car!

The average homeowner on solar will have maybe 4kWh arrays, and a car with maybe 60-80kWh battery.

Solar won’t help them much. A little, of course….but it won’t be filling the car up for free, unless they only pootle a few miles to town every day or two! I cheer when I’ve got maybe 10-20miles into the ‘tank’

Still…..Every little helps….

[DonkeyApple]

mikeiow said:

Ah, you have industrial scale solar arrays….sure, that will help fill the car!

The average homeowner on solar will have maybe 4kWh arrays, and a car with maybe 60-80kWh battery.

Solar won’t help them much. A little, of course….but it won’t be filling the car up for free, unless they only pootle a few miles to town every day or two! I cheer when I’ve got maybe 10-20miles into the ‘tank’

Still…..Every little helps….

There are probably quite a few households that do have a car that sits outside the house mostly all day, every day and just gets used for the basic Tesco run or the periodic and more exciting long distance Costco run. And they've been joined by some WFH folks who no find themselves at home during daylight on weekdays.

It's quite an interesting array of usage types these days across the U.K.

[mikeiow]

DonkeyApple said:

There are probably quite a few households that do have a car that sits outside the house mostly all day, every day and just gets used for the basic Tesco run or the periodic and more exciting long distance Costco run. And they've been joined by some WFH folks who no find themselves at home during daylight on weekdays.

It's quite an interesting array of usage types these days across the U.K.

Also aided to now by the fact that EVs are horribly expensive - a good £10K more than any equivalent ICE car, hence purchase by older/retired/semi-retired boomers (I just about slide into that description myself!).....

This will get more interesting over coming years, as cars get more able to feed homes, and devices get smart enough to flip-flop their energy consumption according to spot pricing.....

For now, I like 'simple' - happy with a more limited shorter off-peak that doesn't desperately need things juggling to fix. Enjoy our battery capabilities - even MrsMikeIOW is happy to check solar and/or battery to see if there is power to run the washer/dryer - must be simple

[dmsims]

mikeiow said:

Also aided to now by the fact that EVs are horribly expensive - a good £10K more than any equivalent ICE car,

Just specced a Golf (that was slower) and it was within £4K of an ID3

[mikeiow]

dmsims said:

mikeiow said:

Also aided to now by the fact that EVs are horribly expensive - a good £10K more than any equivalent ICE car,

Just specced a Golf (that was slower) and it was within £4K of an ID3

Wowsa!
I recall seeing news about the ID3/4 having reductions earlier this year. Maybe things are closer to an equalising than I thought!!

44k miles over 4 years in our Kona EV now.....ought to think about the next upgrade.....might be the new Kona *next* year...but really, ours is just great as it is - still feels taught, got a free battery replacement (worldwide programme after half a dozen fires....)....

[DonkeyApple]

mikeiow said:

dmsims said:

mikeiow said:

Also aided to now by the fact that EVs are horribly expensive - a good £10K more than any equivalent ICE car,

Just specced a Golf (that was slower) and it was within £4K of an ID3

Wowsa!
I recall seeing news about the ID3/4 having reductions earlier this year. Maybe things are closer to an equalising than I thought!!

44k miles over 4 years in our Kona EV now.....ought to think about the next upgrade.....might be the new Kona *next* year...but really, ours is just great as it is - still feels taught, got a free battery replacement (worldwide programme after half a dozen fires....)....

Price parity is much closer today and the % sales rules coming in next year seem likely to drive us to pretty much purchase parity.

But it's not really the cost of the car that is the affordability issue but the cost of the driveway. Even amongst the higher income levels that are the market for £40k cars (an arbitrary RRP where parity is pretty much close enough) or even if we consider all the used EVs now under £20k so highly affordable, it's not the price of the car but the cost of the driveway that is the hinderance along with the statistical reality that aligns the ownership of larger properties with higher skilled jobs and shorter commutes and more nuclear families meaning far less issues when it comes to daily range and where there is an issue a second or third car is simply put on that driveway.

It's not that today you need to be wealthy to obtain an EV, pretty much any old office worker can get a Tesla, they key is that you need to be wealthy to store and refuel that Tesla. In simplistic terms.