PV and battery quote

[Pocster]

So!

 

What do you guys think?

 

The total price for a 4.55kWp Solar PV system & a Tesla Powerwall 2 battery is £12,920 zero vat, excluding scaffolding.

 

 

System peak power output	4.55 kWp
Panel orientation	East/West
Number of panels	14
Panel arrangement	TBC
Inverter specification	Fronius Primo 3.6 Dual MPPT
Mounting type	T-hook & rail
Total annual estimated electricity production	3,581 kWh   Your System GuaranteesSolar PV Modules 25 year performance guarantee ensuring 80% minimum output after 25 years. 25 year manufacturer’s warranty Inverter 7 year warranty Other materials x will pass on the benefit of warranties received in respect of all other supplied materials Installation x offers a 2 year workmanship warranty     Battery Storage SpecificationBattery type Tesla Powerwall 2.0 inc Backup Gateway Battery location TBC Usable Capacity 13.5 kWh Standard continuous power 3.68 kW Weight 125 kg Dimensions Height:1150mm Width:755mm Depth:155mm Mounting options External or Internal wall mounted   Your System GuaranteesTesla Powerwall 2.0 10 years – unlimited cycles Other materials x will pass on the benefit of warranties received in respect of all other supplied materials Installation x offers a 2 year workmanship warranty

[ProDave]

Assume you will generate 3200 kWh per year, and because you have batteries you will use it all (ignoring losses in charge / discharge) and your electricity costs 14.8p per kWh.   Then you will save £473 per year off your electricity bill.

 

So to just repay the £12920 install cost will take you 29.6 years.

 

It will be worse than that, as there are scaffold costs to be added to that quote. In that time you will probably have to replace the inverter at least once, and I doubt the batteries will last the 29 years.  So you will be throwing money at it to repair / maintain it, even before it has repaid it's cost.

 

There is no longer any FIT payments and you won't be exporting anything so the export payment scheme is irrelevant.

 

Sorry to rain on your parade, but it makes no sense to pay anything like that much imho.

[Markblox]

Totally agree with ProDave, just fit a changeover switch and a Tesla Cybertruck! It has a 230V inverter and plug that in. LOL.

[SteamyTea]

11 minutes ago, ProDave said:

electricity costs 14.8p per kWh

How do the numbers change if you add 0.5p to the kWh price every year.

[ProDave]

4 minutes ago, SteamyTea said:

How do the numbers change if you add 0.5p to the kWh price every year.

I will let someone else do a spreadsheet.  But it will shorten the payback time obviously.  At the end of my example 29 years, your electricity price would have nearly doubled.

 

To counter that argument, if you had instead put your £12,920 into the best savings account you could what would that have compounded up to?

[mike2016]

You can move to a night saver tariff and get an even cheaper rate - I've a 6 kW battery and am doing that now with a similar sized array. Paying 9c per kW for 9 units and 18c per kW for 3 units per day currently from the grid. The battery charges overnight. Plus you can investigate the new option to use the Powerwall in a blackout - moving into possible separation of the UK from the EU grid inter-connector next year it might be more useful than you think? I think it's a great price for a powerwall imo. And anything you can do to generate rather than consume from coal power plants at peak times is welcome to0. Agree the finances don't line up but pushing PV excess back to the local grid saves tramissions losses from fossil fuel power plants. It all adds up. Hope you go for it! 

[ProDave]

34 minutes ago, mike2016 said:

moving into possible separation of the UK from the EU grid inter-connector next year it might be more useful than you think?  

That's a new slant on project fear that I have not heard before.

[Pocster]

37 minutes ago, mike2016 said:

You can move to a night saver tariff and get an even cheaper rate - I've a 6 kW battery and am doing that now with a similar sized array. Paying 9c per kW for 9 units and 18c per kW for 3 units per day currently from the grid. The battery charges overnight. Plus you can investigate the new option to use the Powerwall in a blackout - moving into possible separation of the UK from the EU grid inter-connector next year it might be more useful than you think? I think it's a great price for a powerwall imo. And anything you can do to generate rather than consume from coal power plants at peak times is welcome to0. Agree the finances don't line up but pushing PV excess back to the local grid saves tramissions losses from fossil fuel power plants. It all adds up. Hope you go for it! 

Yes ; I think octopus energy have a 1am to 4am window at 5p per kWh .

It can’t just be on the figures I think . Add in an EV ( and you charge off pv for that some of the time ) then the benefits improve . It did seem like a good price .

Also - what will the cost be of ‘grid’ electric going forward per kw ? . 
I kind of see it like buying a car . I could spend 5k I could spend 20k - common sense would be the 5k car ....

To do it now ( and exclude vat as part of a new build ) has its advantages.

Figures wise it doesn’t add up ( nor does the 20k car ) - but at least I’m trying to be off coal etc ...

Edited January 8, 2020 by pocster

[SteamyTea]

44 minutes ago, mike2016 said:

6 kW battery

 

44 minutes ago, mike2016 said:

9c per kW for 9 units and 18c per kW for 3 units

Is that meant to be kWh.

 

(some places have different rated depend on the power (the kW) that can be supplied)

[ProDave]

You can do EXACTLY the same for the environment by doing as I did and spending as little as possible (£1500 in my case) to DIY install a 4kWp solar PV system.  I might add battery storage at some point when that too becomes cheap enough to DIY install.

 

 

[Pocster]

1 minute ago, ProDave said:

You can do EXACTLY the same for the environment by doing as I did and spending as little as possible (£1500 in my case) to DIY install a 4kWp solar PV system.  I might add battery storage at some point when that too becomes cheap enough to DIY install.

 

 

There PV figures (no battery)

 

 

System peak power:

4.55 kWp

Annual output:

3,581 kWh

Solar energy used on site:

1,791 kWh

Your bill saving after year 1:

£304

Your bill saving after year 25:

£19,456

CO2 saving after year 1:

1,941 kg

CO2 saving after year 25:

37,850 kg

[Pocster]

I',m confused. According to that you pay of the near 13k long before 25years....

 

Answer my own question!....

 

The estimated value of your new system in year one is £304 based on annual electricity bill savings, assuming a daytime electricity rate of 17p and that you are able to consume 50% of the power generated. Your bill saving will increase as electricity prices rise or if you are able to consume more than 50%. Over 25 years – the life of your panels – your bill savings could exceed £19,456, if electricity prices increase by 8% per annum.

Edited January 8, 2020 by pocster

[SteamyTea]

50 minutes ago, ProDave said:

To counter that argument, if you had instead put your £12,920 into the best savings account you could what would that have compounded up to?

I will counter, counter that with inflation.

 

50 minutes ago, mike2016 said:

but pushing PV excess back to the local grid saves tramissions losses from fossil fuel power plants.

Most of the losses are at the local, not on the bulk transport.

As individuals we have little say in the amount of coal used in power generation.  That has be set by international agreements enacted by our parliament.

what has happened is that we have swapped out coal for gas and biomass to a certain extent.  large commercial wind generation is now starting to take up some of the slack, as is large scale solar.

Small scale solar is also contributing, but this is hard to establish the true amount as it is not metered very well.

[ProDave]

7 minutes ago, pocster said:

There PV figures (no battery)

 

 

System peak power:

4.55 kWp

Annual output:

3,581 kWh

Solar energy used on site:

1,791 kWh

Your bill saving after year 1:

£304

Your bill saving after year 25:

£19,456

CO2 saving after year 1:

1,941 kg

CO2 saving after year 25:

37,850 kg

Someone's maths is a bit suspect.

 

If they estimate you will save £304 per year, then after 25 years, that would be £7,600 saved.

 

They are saying £19,456 so they must be calculating a BIG increase in electricity prices, but giving you no figures to scrutinise what assumptions they may have made.

 

Also, if you are saving 1941kg CO2 per year, after 25 years that would be 48,525 so why are they saying only 37,850?  Are they factoring in a drop in performance over that time?

 

[Pocster]

1 minute ago, ProDave said:

Someone's maths is a bit suspect.

 

If they estimate you will save £304 per year, then after 25 years, that would be £7,600 saved.

 

They are saying £19,456 so they must be calculating a BIG increase in electricity prices, but giving you no figures to scrutinise what assumptions they may have made.

 

Yeah sorry ; cross posted . They assume a 8% annual increase in electric which does sound on the rather high side !!

[vivienz]

It's nowhere near as pretty as a tesla powerwall, but I've had a battery system installed recently.

 

My solar PV is a 5.4kWh system, 18 panels GCE mounts.  All in with installation, £8k, back in 2018. 

The battery system is made up of 6 x 2.4kW Pylontech batteries @ £610 each and 2 AC controllers set up in parallel, £595 each.  All prices ex VAT - I can reclaim this as part of the new build.

Total cost, including install and bits and pieces, £5.6k.  The whole thing has a changeover switch so, in the event of a power cut, I can isolate the system and still power the essential house systems and the battery controls are set up to always hold 50% charge so that they have some juice if the power does get cut off.

 

So, £13.6k for the whole shebang.

[Jeremy Harris]

I was after a very similar battery system, but it seems that the arrangement I thought I had for buying one has fallen through.  Pity, as I've had the set up, cabling, shed to locate everything etc sitting waiting ready for the stuff to arrive, and the cash sitting herewaiting to pay for it, since early last year...

 

 

[Pocster]

11 minutes ago, Jeremy Harris said:

I was after a very similar battery system, but it seems that the arrangement I thought I had for buying one has fallen through.  Pity, as I've had the set up, cabling, shed to locate everything etc sitting waiting ready for the stuff to arrive, and the cash sitting herewaiting to pay for it, since early last year...

 

 

Actually @Jeremy Harris ; can I ask a question where I assume I’ve vastly over simplified things ....

 

As you have an EV how many ‘miles’ can you get from a 5p per kw charge for 4 hours ?

Just trying to compare electric cost against petrol cost for same distance ( also assuming of course not using pv for charge ) . I don’t have an EV - but certainly would want at least the cabling in place ready for a charge point . 
If you did include PV and assume you charge your vehicle 50% pv and 50% 5p kw - wonder what that does to the figures . Actually perhaps this isn’t so simplistic ?

Edited January 8, 2020 by pocster

[SteamyTea]

10 minutes ago, pocster said:

‘miles’ can you get from a 5p per kw charge for 4 hours

EVs are measured in kWh/100 km (usually)

This can be reduced to Wh/km.

Then converted to Wh/mile.

 

As small EV (Leaf or Zoe) can does around 220 Wh/mile.

So your 5p/kWh will buy you 4.5 miles or 1.1p/mile.

 

Taking a small gasoline powered car that does 50 MPG.

A gallon costs around £5.50, so 11p/mile.

 

A larger EV will use around 300 to 400 Wh/mile.

[Andrew]

With my 7kW charger I could pump in 28 kWh in four hours at a total cost of £1.40 (5p per kWh and ignoring losses).

 

My Tesla model S will do 3 miles per kWh at normal speeds, so that’s 84 miles / 1.66p per mile.

 

Btw I owned an old Leaf for about a year and 220 Wh/mile would need very steady driving, forget going faster than 55mph. The figures above for the Tesla are perfectly doable at 70mph on the motorway.

[nod]

3 hours ago, pocster said:

So!

 

What do you guys think?

 

The total price for a 4.55kWp Solar PV system & a Tesla Powerwall 2 battery is £12,920 zero vat, excluding scaffolding.

 

 

System peak power output	4.55 kWp
Panel orientation	East/West
Number of panels	14
Panel arrangement	TBC
Inverter specification	Fronius Primo 3.6 Dual MPPT
Mounting type	T-hook & rail
Total annual estimated electricity production	3,581 kWh   Your System GuaranteesSolar PV Modules 25 year performance guarantee ensuring 80% minimum output after 25 years. 25 year manufacturer’s warranty Inverter 7 year warranty Other materials x will pass on the benefit of warranties received in respect of all other supplied materials Installation x offers a 2 year workmanship warranty     Battery Storage SpecificationBattery type Tesla Powerwall 2.0 inc Backup Gateway Battery location TBC Usable Capacity 13.5 kWh Standard continuous power 3.68 kW Weight 125 kg Dimensions Height:1150mm Width:755mm Depth:155mm Mounting options External or Internal wall mounted   Your System GuaranteesTesla Powerwall 2.0 10 years – unlimited cycles Other materials x will pass on the benefit of warranties received in respect of all other supplied materials Installation x offers a 2 year workmanship warranty

We didn’t want solar panels simply because we don’t like the look of them Even though our planing permission stated that we must include them 

Our sap stated an installation cost of £7500 and an annual saving of about £250 

Unless you can buy and fit cheaply 

The figures don’t stack up 

 

Our daughter and her partner have looked at purchasing two houses with solar panels Both have come back with damming surveys 

They read like the roof was about to fall in in any minute 

Surveyors don’t like them

[SteamyTea]

20 minutes ago, nod said:

They read like the roof was about to fall in in any minute 

Surveyors don’t like them

If those modules were fitted in the last 5 years or so, there should be a structural engineers' reports that show that the roof is safe.

 

21 minutes ago, nod said:

We didn’t want solar panels simply because we don’t like the look of them

They do not have to stick up like a sore thumb, they can be roof integrated.

[Jeremy Harris]

2 hours ago, pocster said:

Actually @Jeremy Harris ; can I ask a question where I assume I’ve vastly over simplified things ....

 

As you have an EV how many ‘miles’ can you get from a 5p per kw charge for 4 hours ?

Just trying to compare electric cost against petrol cost for same distance ( also assuming of course not using pv for charge ) . I don’t have an EV - but certainly would want at least the cabling in place ready for a charge point . 
If you did include PV and assume you charge your vehicle 50% pv and 50% 5p kw - wonder what that does to the figures . Actually perhaps this isn’t so simplistic ?

 

 

It varies a great deal.  In warm weather, with a light foot, you might manage around 230 Wh/mile, in cold, wet weather, then 350 Wh/mile might be more typical.  Since November last year I've been averaging 284 Wh/mile, over a mix of long and short trips.  Short trips are the worst, in winter, as initially heating the car up takes a fair bit of energy.

 

So, if you were paying 5p/kWh and charging at the normal domestic maximum of around 7 kW, with an average consumption of around 275 Wh/mile, then 4 hours of charge would get a bit over 100 miles of range, for a cost of around £1.40, or 1.4p/mile. 

 

I charge in winter at E7 rates, so 8.148p/kWh, so can add around 178 miles of range on an overnight E7 charge, at a cost of around £4.00, or about 2.25p/mile. 

 

[nod]

50 minutes ago, SteamyTea said:

If those modules were fitted in the last 5 years or so, there should be a structural engineers' reports that show that the roof is safe.

 

They do not have to stick up like a sore thumb, they can be roof integrated.

It just seemed observed that planners insisted we had sash widows and where quite specific about the type of slate we used 

Definitely no type of tiles No external aerial or satellite dish 

Then insist we put something so modern on the roof 

The integrated look for better than the type that are just perched on top of the tiles 

But neither of us like the look of solar panels 

Perhaps we would think differently if they where cost effective 

Our final Sap score was 89 I was amazed that with the whole back of the house covered in solar panels would only have taken the score up to 91

 

[MikeSharp01]

4 hours ago, ProDave said:

To counter that argument, if you had instead put your £12,920 into the best savings account you could what would that have compounded up to?

Net present value / Real rate of return needs also to factor in inflation as this eats away at investment now over time against interest lost or otherwise paid.