Solar Panels UK - is it worth it?

[notmeguv]

So for me, retirement age, I have "hedged" any price change on electricity, and I'm doing my bit to be Eco (which is important to me)

Hedging against future price increases was one of the main reasons I went ahead with the install. Even if I don’t hit ‘payback’ at the 10 year mark (far too early to tell), we’re hopefully looking to retire early in 3-5 years time and in my mind, reducing the monthly outgoings and protecting against higher electricity prices only helps that to happen earlier.

I could have left the money invested but it’s either making a small amount of interest on savings or it’s taking a risk in investments. What I’ve actually done is dump the cost of the solar install on a 14 month interest free credit card and put the cash in premium bonds. So hopefully I’ll have a few PB wins over the next year or so before having to pay it off

 

[WannabeOwner]

I could have left the money invested but it’s either making a small amount of interest on savings or it’s taking a risk in investments.

You've got to pay tax on that investment too. Might be Man Maths?, but no tax to pay on the savings you make not paying 75% of you Electricity Bill

 

[Pink Duck]

My electricity annual estimate has gone up a bit since solar and battery, mostly from arbitrage on overnight 7.5 p/kWh to evening 15 p/kWh export.

 

[PITA]

My electricity annual estimate has gone up a bit since solar and battery, mostly from arbitrage on overnight 7.5 p/kWh to evening 15 p/kWh export.

Yeah, I didn't think of that... I bet 2024 will be interesting for us as well...

See how much we push through the Powerwalls

 

[Js1977]

Yeah, I didn't think of that... I bet 2024 will be interesting for us as well...

See how much we push through the Powerwalls

Yes, indeed. It will also be interesting with VAT being abolished for batteries from February, what this does to the "landscape"

 

[WannabeOwner]

See how much we push through the Powerwalls

Mine are showing 8MWh for the year (about 50:50 filled from PV / Grid)

PV generated 15 MWh

 

[Pink Duck]

m = milli (1/1000th), M = mega (10^6 = 1,000,000)

I recently passed the 4 MWh mark with system install date of 23rd June 2023.

 

[WannabeOwner]

m = milli (1/1000th), M = mega (10^6 = 1,000,000)

Hehehe .. .Thanks (and fixed)

 

[WannabeOwner]

install date of 23rd June 2023.

Not sure if comparable, but in terms of pro-rata here are my monthly figures this year

	Of best month	Of year	kWh
Jan	18%​	3%​	388​
Feb	33%​	5%​	736​
Mar	42%​	6%​	918​
Apr	81%​	12%​	1782​
May	89%​	13%​	1976​
Jun	100%​	15%​	2209​
Jul	83%​	12%​	1833​
Aug	83%​	12%​	1837​
Sep	66%​	10%​	1460​
Oct	39%​	6%​	862​
Nov	23%​	3%​	509​
Dec	12%​	2%​	256​

Dec 134 (1st-18th) (used last year's figure of 256) - basically in Dec if it is sunny then 10-18 kWh, otherwise 1-5kWh)

 

[Pete UK]

Not sure if comparable, but in terms of pro-rata here are my monthly figures this year

	Of best month	Of year	kWh
Jan	18%​	3%​	388​
Feb	33%​	5%​	736​
Mar	42%​	6%​	918​
Apr	81%​	12%​	1782​
May	89%​	13%​	1976​
Jun	100%​	15%​	2209​
Jul	83%​	12%​	1833​
Aug	83%​	12%​	1837​
Sep	66%​	10%​	1460​
Oct	39%​	6%​	862​
Nov	23%​	3%​	509​
Dec	12%​	2%​	256​

Dec 134 (1st-18th) (used last year's figure of 256) - basically in Dec if it is sunny then 10-18 kWh, otherwise 1-5kWh)

That’s really useful. Remind me, how many panels do you have / kW size of array and are all your panels south facing?

So far, with my tri-directional 11.34kW arrays (N, S, E) I’ve got this for about 5 and a half months use (need to brush up on my table pasting skills). If my April, May, June figures generated come in with similar proportions to yours I’ll be really happy.

Total: 2,580 kW (5 months 19 days)
Installer annual forecast: 6,950kW

It’s looking a bit short of my installers forecast so far - but with an extra 3 good months in April, May, June who knows ! I’m predicting my generation is going to be about 15% short of their estimate.

I was 97% off peak use in the last 30 days according to the Octo-Aid app (which is brilliant by the way). And that’s including a calibration. So effectively still 100% off peak use still and able to export a bit in the evenings as well. Which I am thrilled about as it’s far better than I expected by mid December.

With the increased 15p export rates and Octopus savings sessions I’m anticipating at least a zero bill for my yearly electricity and hopefully a small profit of some sort, although not critical. So that’s a £5,000 pa electric saving for us using today’s IO Octopus prices, whilst powering the house and Tesla for free. Also saving about £2,000 on petrol a year and at least £1,000 on road tax and servicing an ICE car etc.

It’s the batteries that are enabling the majority of the savings for us. I think this has become the most critical part of our system in terms of cost reduction.

Happy Christmas

 

[Drew57]

Also saving about £2,000 on petrol a year and at least £1,000 on road tax and servicing an ICE car etc.

& will go part way to insuring your Tesla as well

 

[phil4]

That’s really useful. Remind me, how many panels do you have / kW size of array and are all your panels south facing?

So far, with my tri-directional 11.34kW arrays (N, S, E) I’ve got this for about 5 and a half months use (need to brush up on my table pasting skills). If my April, May, June figures generated come in with similar proportions to yours I’ll be really happy.


View attachment 1001319

Total: 2,580 kW (5 months 19 days)
Installer annual forecast: 6,950kW

It’s looking a bit short of my installers forecast so far - but with an extra 3 good months in April, May, June who knows ! I’m predicting my generation is going to be about 15% short of their estimate.

I was 97% off peak use in the last 30 days according to the Octo-Aid app (which is brilliant by the way). And that’s including a calibration. So effectively still 100% off peak use still and able to export a bit in the evenings as well. Which I am thrilled about as it’s far better than I expected by mid December.

With the increased 15p export rates and Octopus savings sessions I’m anticipating at least a zero bill for my yearly electricity and hopefully a small profit of some sort, although not critical. So that’s a £5,000 pa electric saving for us using today’s IO Octopus prices, whilst powering the house and Tesla for free. Also saving about £2,000 on petrol a year and at least £1,000 on road tax and servicing an ICE car etc.

It’s the batteries that are enabling the majority of the savings for us. I think this has become the most critical part of our system in terms of cost reduction.

Happy Christmas

July and August were particularly poor this year for me, which may be why you’re short of the estimate.

 

[notmeguv]

I’ve spent the last couple of days playing around with Home Assistant and found some useful stuff.

The Tesla Custom Integration now automatically sets the Powerwall backup reserve to 100% at 23:30 and 10% at 05:30. This ensures it is always fully charged overnight.

The same integration also switches on sentry mode in the car when I get home and Teslausb has any footage to upload to my server. And then switches sentry mode off when upload is complete (sentry mode keeps the car awake while the upload is taking place). This is a good one as before it was relying on me to remember to switch sentry off manually which I forgot on many occasions so wasted a lot of charge on unnecessary drain.

The Octopus Intelligient Tariff integration checks for additional IO slots and if it detects any outside of the normal 6 hours, will switch the Powerwall reserve to 100% ensuring it charges at off-peak rate and stops the house pulling from it. Then switches the reserve back to 10% when the IO slot ends. This also means the Zappi will never drain the Powerwall.

I’ve also configured the Home Connect Alt integration to start the dishwasher overnight if it is in a ready state and the door is shut. This means we just need to pop a tablet in and shut the door. It no longer needs me to remember to set a schedule through my phone before bed.

I think I’m just scratching the surface but pretty happy with these for starters.

 

[Pete UK]

Sounds like you’ve been busy

 

[notmeguv]

Sounds like you’ve been busy

2 weeks off work but put my back out a few days ago so at least it’s something to do while I sit here feeling sorry for myself

 

[Drew57]

2 weeks off work but put my back out a few days ago so at least it’s something to do while I sit here feeling sorry for myself

This means we just need to pop a tablet in and shut the door.

Sounds like both you & the dishwasher need that.

 

[WannabeOwner]

how many panels do you have / kW size of array and are all your panels south facing?

16 South Facing, and 32 (I think) Slightly South of East

I’m predicting my generation is going to be about 15% short of their estimate.

If not already tried you might want to try an estimation with PVWatts

The Tesla Custom Integration now automatically sets the Powerwall backup reserve to 100% at 23:30 and 10% at 05:30. This ensures it is always fully charged overnight.

Useful to know. If I manually force mine to 100% (e.g. at start of Off Peak) (using Self-Powered, rather than Time-Based) the PWs charge at 3.5kW rather than their normal 10kW ... which means that they may not fully charge before Off peak ends. Dunno if you will have that limitation.

 

[ACarneiro]

16 South Facing, and 32 (I think) Slightly South of East



If not already tried you might want to try an estimation with PVWatts



Useful to know. If I manually force mine to 100% (e.g. at start of Off Peak) (using Self-Powered, rather than Time-Based) the PWs charge at 3.5kW rather than their normal 10kW ... which means that they may not fully charge before Off peak ends. Dunno if you will have that limitation.

Even at 3.5kW, 4 hours should be enough to charge them. As we get 6 hours with IOG, that should hopefully not be a problem

 

[WannabeOwner]

Even at 3.5kW, 4 hours should be enough to charge them

In my case 2 of them ... and (IIRC) its 3.5kW for the pair (maybe that's long enough, I haven't done the maths, but my recollection, from when I last did do the maths, is that it was nip-and-tuck)

 

[ACarneiro]

In my case 2 of them ... and (IIRC) its 3.5kW for the pair

Oh, that's interesting.
I'll have so see what mine do. From what I've seen, when they're just charging Off Peak they are usually pulling 3.5kW each...