ET asks for advice!

Exiled_Tyke

I've had a firm quote these. And no I haven't had a failure of competence and I am still confident in my judgement but just thought I'd 1) take a check to make sure. AND 2) get some opinions on the choices here.  So I would appreciate any views.  The prices look OK to me (well for the bigger options).  Generation estimates are about right.  Payback and savings figures are always to be taken with scepticism in my view: I'll do my own maths on those.   Optimisers not needed.  System will be half East and half West.  Firm is reputable so no qualms there.   Any other thoughts I'd be grateful for.  Cheers.  

Quick Quote Overview - Bisol 375Wp mono-black panels

Generation Estimate

Financial Estimates

No. Panels

Battery info

Price

Capacity

MCS

Payback time

Annual benefit

Annual ROI

Lifetime Profit

1

10 panels

No battery

£4,935.00

3.75 kWp

2666 kWh

9 years

£370

15.4%

£14,116

2

14 panels

No battery

£5,985.00

5.25 kWp

3733 kWh

9 years

£461

15.3%

£16,951

3

18 panels

No battery

£7,507.50

6.75 kWp

4799 kWh

10 years

£540

13.8%

£18,428

Options 1b, 2b & 3b are exactly as above options 1, 2 & 3 but with added battery storage

1b

10 panels +

5.2kWh Li Ion battery

£7,612.50

3.75 kWp

2666 kWh

8 years

£501

16.4%

£23,606

2b

14 panels +

8.2kWh Li Ion battery

£9,502.50

5.25 kWp

3733 kWh

8 years

£793

18.8%

£35,208

3b

18 panels +

8.2kWh Li Ion battery

£11,025.00

6.75 kWp

4799 kWh

8 years

£902

17.9%

£38,415

Extra features and options

1

Solar iBoost Immersion controller

£420

Divert surplus generation into the immersion heater for hot water

2

Battery upgrade

£840

To upgrade from 5.2kWh to 8.2kWh battery

3

Panel Optimisers

£45

Individual panel optimisers to optimise shaded panels' performance

4

Power cut battery back up (10A)

£473

Automatically run a lighting circuit and a single socket up to 10A (2.3kW) powered by the battery in a power cut

5

MyEnergi Zappi EV charger

£893

Smart electric vehicle charge controller

6

Bird mesh (cost per panel)

£37

Wire mesh around the panel edges to prevent birds nesting underneath

7

WiFi monitoring portal

Included

WiFi connection to an online monitoring portal

Hexane

If using a Zappi for EV charging, then I would want any immersion controller to be from myenergi as well.

QrizB

The solar prices aren't terrible.

The extra price for the battery isn't terrible either.

The ROI figures look ... optimistic.

Coastalwatch

Hi ET, I can only speak from my experiences here having installed the largest array our SSE facing roof would take having been guided in that direction from the brains trust here. I think they know who they are! 28 x 295W panels, plus a couple on the WSW facing gable end, total 8.85 kWp. Their annual generation approx equates to our domestic consumption and 4k miles of EV travel so I don't regret for one minute going the whole hog, complete with bird/squirrel proofing.

I guess it depends upon how far the owners wish to go with regard to aiming for a net zero lifestyle or whether its just a hedge against rising energy prices while still maintaining FF's for heating and travel!

If like us they are intent on relying on electricity only in future then the paragraph below might proof helpful.

The PV array was installed four years ago, subsequent to which we've added, EV, Zappi, a2ashp x 2, thermal store, Eddi and just recently a couple of 8.2 kWh batts. In winter the latter two being charged on the Octopus Go Faster tariff 01.30 to 06.30hrs which then just about see us through most of the daytime rate with only minor incursions into it.

While we might envy your E/W orientation in the summer months then in winter the reverse might prove to be the case when output is decidedly limited.

JKenH

@Exiled_Tyke you don’t say whether you have existing south facing panels but I am presuming you do have. If you don’t then you can ignore what follows. 

With south facing panels you will already have picked the low hanging fruit and the gains you get from adding an E-W array will be limited, particularly in winter as @Coastalwatch has commented. If you have a battery you would be better adding more to a south facing roof if you have space. In November, December and January, I generated just 353kWh from my E-W 7.8 kw of panels (45 Os). A neighbour who has an SSE orientation produced 451 kWh from just 4kw (113 Os). OK, my panels aren’t at their best but even when new I only made 90% of my December PVGIS estimate of 115.6 kWh ( 14.8 Os). You are at a not dissimilar latitude and might find the same discrepancy against PVGIS for East and West roofs. 

Just have a look out an east facing window about 8am this time of year and see how low the sun is in the sky. Your panels would have been optimally aligned 2 hours earlier and by the time the sun does reach any height it is just glancing the roof.

In summer West facing solar is great for cooking tea and a couple of hours TV - you have so much sunlight that time of year that you barely need a battery to get through the evening and your battery would probably see you through breakfast so you might not gain much from the East roof. In winter when you have already run out of battery by breakfast the east roof won’t have woken up and won’t be any use to you. 

If you are like me though you probably just want to add some panels anyway, (s*d the economics), but with one eye on the pennies I would go for the west roof and a slightly bigger battery and not bother with the east roof. 

Edit: The argument for West over East is considerably improved by British Summer Time which shifts our generation one hour later in the day so in August it is just getting dark at 9pm whereas if we stayed on GMT it would be getting dark at 8. We have our tea at 6pm when we have 3kw on BST in the height of summer but it would only be around 2 kw on GMT.

Exiled_Tyke

Thanks everyone and sorry for the delay in responding.  You have confirmed my thoughts so your comments are very much appreciated. 

EV charger already installed so it's not really cost effective to replace with a Zappi sadly.    

Also no South facing orientation available - this would have been the first to exploit.   

The residents (close family) actually wanted to just go with East to avoid spoiling the look of the property from the road. It's taken some persuasion to get them to agree to the West!    

Verdigris

An in-roof installation would look more aesthetically pleasing, although it costs more to install. There is also a slight loss in efficiency, owing to the panels getting hotter, but that may less of an issue with E/W arrays.