5 vs 10 Solar Panels with Battery from Octopus – Advice Needed for Future EV & Heat Pump

Sam3007

Hi all,

I’ve just received a solar PV quote from Octopus Energy and would really appreciate some advice from anyone with experience or knowledge in this area!

Here’s what I’ve been offered:

• Panels: 5 x 450W JA Solar panels (total 2.25 kW, south-facing, no shade) (25-year warranty)

• Inverter: 5 x Enphase IQ8 microinverters (25-year warranty)

• Battery: Enphase 5 kWh (15-year warranty)

• Bird mesh: Included (brand not specified)

• Monitoring: App included

• Installer: Octopus Energy, using MCS Accredited Installers

• Warranties: 25 years (panels & inverters), 15 years (battery), 5 years (installation), HIES insurance-backed

Cost breakdown:

• System price: £9,286.66 

• Scaffolding: £1,007.34 

• Total: £10,294 

• Finance: 0% over 3 years available

Estimated savings:

• Old bill: £242/month → New bill: £35/month (I don't know why they estimted by bill to be £242 as I am only paying around £140 a month - consuming around 2800 KWH for electricity and 4300 for gas per year)

My situation & questions:

• I’m planning to get an electric vehicle soon (I drive 10–15,000 miles/year) and may add a heat pump in the future.

• The roof is south-facing with no shade, but I could potentially fit 5 more panels on the other side (so 10 in total - new quote would be £11700 - 328 monthly intallments for 3 years)

• I’m wondering if it’s worth getting 10 panels instead of 5, and whether I should upgrade to a 10 kWh battery to make the most of off-peak charging and future-proof for the heat pump.

• Are the brands (JA Solar, Enphase) and Octopus Energy’s installers generally considered good/reliable?

• Any tips, things to watch out for, or questions I should ask on my next call with Octopus?

Would love to hear from anyone who’s been through this process or has thoughts on the best setup for my needs.

Thanks in advance!

Peter999_2

Hi.

How much extra would they charge for the Tesla Powerwall 3?     If I'm not mistaken, the package they have offered will not power the house during a powercut but the Tesla will unless you are getting an IQ system controller.  Maybe check with them and see if they are providing a controller as well for the price.

Also, I think the Tesla is 13kWh is not much more as Octopus have recently dropped the price by £1,000 for it.     I have heard good things about the Enphase though - and I think the the warranty is longer for that than the Tesla - however, Tesla are fantastic for the batteries keeping their capacity (just look at their cars).

I, like you, am also looking into it.  My friend got a Tesla Powerwall 3 system and uses the Octopus Intelligent Flux tariff which is making him quite a lot of money (he has 13 panels though).     He absolutely swears by the Tesla and had a powercut for a few hours (he only knew because the tesla app told him).   

For the other 5 panels, you say you'd put it on the other side - do you mean it would be north facing?   If yes then obviously it's not going to be as good as the south facing though I have read people mentioning that it is still worth it for the amount it does get.

The 3 year at 0% is great as well.   You could make about £480 in interest a year by using that instead of paying it in full.

QrizB

Your quotes look rather expensive for what you're getting.

So long as there's nothing especially complicated about the installation, @Screwdriva can probably put you in touch with someone who can install 5kWp (10 x 500 watt panels) and a Tesla Powerwall 3 with 13.5kWh of storage for less than the £11.7k you've been quoted for 4.5kW and 5kWh.

Screwdriva

Sam3007 said:

My situation & questions:

• I’m planning to get an electric vehicle soon (I drive 10–15,000 miles/year) and may add a heat pump in the future.

• The roof is south-facing with no shade, but I could potentially fit 5 more panels on the other side (so 10 in total - new quote would be £11700 - 328 monthly intallments for 3 years)

• I’m wondering if it’s worth getting 10 panels instead of 5, and whether I should upgrade to a 10 kWh battery to make the most of off-peak charging and future-proof for the heat pump.

• Are the brands (JA Solar, Enphase) and Octopus Energy’s installers generally considered good/reliable?

• Any tips, things to watch out for, or questions I should ask on my next call with Octopus?

Would love to hear from anyone who’s been through this process or has thoughts on the best setup for my needs. 

- JA Solar is an inexpensive (wholesale) Chinese owned brand with a poor ethical record. 

- I would recommend maximizing the # of panels that will fit on your South/ West/ East aspects. I would not invest in a North facing aspect. 

- A Tesla Powerwall 3 is the most capable battery inverter solution in the UK and is superior to Enphase in nearly every scenario outside of highly shaded roofs.

- When paired to 5 X 500W bifacial panels, it will cost < £9K. When paired to 10 X 500W panels, it will cost < £11K. 10 year workmanship warranty & bird netting included, via installers I use to help other MSE forum members. 

Hope this helps! 

Sam3007

Peter999_2 said:

Hi.

How much extra would they charge for the Tesla Powerwall 3?     If I'm not mistaken, the package they have offered will not power the house during a powercut but the Tesla will unless you are getting an IQ system controller.  Maybe check with them and see if they are providing a controller as well for the price.

Also, I think the Tesla is 13kWh is not much more as Octopus have recently dropped the price by £1,000 for it.     I have heard good things about the Enphase though - and I think the the warranty is longer for that than the Tesla - however, Tesla are fantastic for the batteries keeping their capacity (just look at their cars).

I, like you, am also looking into it.  My friend got a Tesla Powerwall 3 system and uses the Octopus Intelligent Flux tariff which is making him quite a lot of money (he has 13 panels though).     He absolutely swears by the Tesla and had a powercut for a few hours (he only knew because the tesla app told him).   

For the other 5 panels, you say you'd put it on the other side - do you mean it would be north facing?   If yes then obviously it's not going to be as good as the south facing though I have read people mentioning that it is still worth it for the amount it does get.

The 3 year at 0% is great as well.   You could make about £480 in interest a year by using that instead of paying it in full.

Octopus website do have a calculator which gives me 12,800 for 10 panels and the Tesla power wall 3. I believe scaffolding would be around £1500.
The price becomes 12,200 for five panels with Tesla battery and 13060 with 12 panels!!

The other side of the roof is north east facing and I’ve read one can generate up to 45% compared to the Northwest side.
I also read that people are complaining about octopus trying to reduce the number of panels. I believe my roof can take six panels on each side!

Sam3007

Screwdriva said:

Sam3007 said:

My situation & questions:

• I’m planning to get an electric vehicle soon (I drive 10–15,000 miles/year) and may add a heat pump in the future.

• The roof is south-facing with no shade, but I could potentially fit 5 more panels on the other side (so 10 in total - new quote would be £11700 - 328 monthly intallments for 3 years)

• I’m wondering if it’s worth getting 10 panels instead of 5, and whether I should upgrade to a 10 kWh battery to make the most of off-peak charging and future-proof for the heat pump.

• Are the brands (JA Solar, Enphase) and Octopus Energy’s installers generally considered good/reliable?

• Any tips, things to watch out for, or questions I should ask on my next call with Octopus?

Would love to hear from anyone who’s been through this process or has thoughts on the best setup for my needs. 

- JA Solar is an inexpensive (wholesale) Chinese owned brand with a poor ethical record. 

- I would recommend maximizing the # of panels that will fit on your South/ West/ East aspects. I would not invest in a North facing aspect. 

- A Tesla Powerwall 3 is the most capable battery inverter solution in the UK and is superior to Enphase in nearly every scenario outside of highly shaded roofs.

- When paired to 5 X 500W bifacial panels, it will cost < £9K. When paired to 10 X 500W panels, it will cost < £11K. 10 year workmanship warranty & bird netting included, via installers I use to help other MSE forum members. 

Hope this helps! 

Thanks. I will see to fit as many as I can on both NW and SE sides

Does having biracial panels make much difference on the roof of a house ?

Screwdriva

Sam3007 said:

Thanks. I will see to fit as many as I can on both NW and SE sides

Does having biracial panels make much difference on the roof of a house ?

Not sure about the biracial element but bifacial panels can make a difference on a roof

Sam3007 said:

I believe my roof can take six panels on each side!

12 X 500W Eurener bifacial panels + Tesla PW3 = £11K installed. Why pay Octopus more for less? 

Martyn1981

Hi Sam, just to say that I went with both roofs on my house, so ESE and WNW. Roughly the opposite of yourself, which seem to be SW + NE(?) butyou will see a bigger difference as you have a 'better' roof than me (SW v's ESE), and worse than me (NE v's WNW).

My thought process on the dual roof conundrum is to compare the generation to the additional cost. This is not a rule, guide or anything like that, just my personal way to rationalize it.

So for instance, say you were fitting 3kWp on a 'good' roof for £4k, but could 3kWp on a 'bad' roof at the same time for a total of £6k, then if the bad roof adds 50% more generation for the 50% increase in cost, then it's worth at least pondering further before you decide.

Crucially, the roofs need to be done at the same time so some costs can be shared, to avoid doubling the cost.

Not sure where you are, but I used PVGIS just to get some quick comparisons, and stuck a random pin in Leicester just for discussion purposes.

I then left all the boxes alone, apart form the system size where I put in 1 (for 1kWp so we can compare generation as a ratio). I entered 35d for roof pitch (again just for a comparison). Then entered roof orientations to get annual generation figures for us to compare.

For south facing (zero azimuth) it gave me 1,032kWh of generation per year.
For south west (+45d azimuth) it gave me 946kWh.
For north east (-135d azimuth) it gave me 593kWh.

So compared to south facing panels NE is ~57.5%, and compared to the SW roof, it is ~63%.

Again, this is just my (perhaps odd) way of thinking, but if you get a quote you are happy with for the SW roof, then if you can double the installed kWp using the NE roof for ~63% more cost, then they are kinda comparable.


But be aware that the losses you see as you go further from south are mostly confined to the poorer solar months. So you will see most of that generation loss in the winter, with very poor generation.

My ESE roof generates roughly 7x more in June v's Dec, but my WNW roof is about 11x. And my steep pitched (winter optimized) SSW groundmount is about 3x.


Apologies if this causes mental overload. 

Sam3007

Screwdriva said:

Sam3007 said:

Thanks. I will see to fit as many as I can on both NW and SE sides

Does having biracial panels make much difference on the roof of a house ?

Not sure about the biracial element but bifacial panels can make a difference on a roof

Sam3007 said:

I believe my roof can take six panels on each side!

12 X 500W Eurener bifacial panels + Tesla PW3 = £11K installed. Why pay Octopus more for less? 

I’m looking to get solar panels with a payment plan similar to Octopus’s offer of 0% interest over at least three years. Do you know any companies in the North West that provide a similar deal? Also, if I’m installing an EV charging point alongside, which brand or model would you recommend with this system ?Thanks 

sheenas

I am not sure I would spend money on battery at this point. You can export energy back to the grid with a right tariff get very good export rates, then buy back what you use. In that scenario more panels makes sense. When you get your ev you can move to an overnight charging tariff which is something like 8p per kw. Once you decide for a heat pump then maybe look at getting a battery. 

Screwdriva

Sam3007 said: 

I’m looking to get solar panels with a payment plan similar to Octopus’s offer of 0% interest over at least three years. Do you know any companies in the North West that provide a similar deal? Also, if I’m installing an EV charging point alongside, which brand or model would you recommend with this system ?

Sadly, I know of no companies that offer 0% financing over 3 years, as this cost is typically passed on to the customer via a higher system quote (as Octopus appears to have done). 

In terms of EV chargers, if you have a Tesla EV and a Powerwall 3, there are benefits in installing a Tesla Charger. Otherwise, the Zappi is likely the best EV PV charger on the market.