solar panels with our without battery, advice would be greatly appreciated

shaz4473

hi, I am hoping to get some advice as I started contacting solar panel installers last year and only just recently had 2 appointments.  We live in the North East of Scotland and they are so busy wait times are long. 
Two quotes now in and comparable in cost but one company I did not get a good feeling about and decided to not move forward with them.  The other company I was given their name by a friend that had work done and was happy with it and good feedback online too in home energy scotland site.

Hoping to get some advice on the additional cost of adding a battery as due to my lack of knowledge I can't get my head around why you would not get a battery and store excess power when available and use it when the solar panels are not generating any, this is where you come in!!

Background info- mum , retired and myself - working 2 days at home and 3 in the office.  South west facing garden with no shading but limited roof area for panels.  Yearly usage was app 2000kwh and now with an electric car I would say no more than 2700kwh as it only gets charged very infrequently and currently on Octopus go overnight at 7.14p /kwh.  Moved here 4 years ago and not intending on moving again.

The salesman did not push for us to get a battery as he advised that payback would increase from 8-9 years with panels to 13 years with a battery.  Here is the info on what was being installed and without a battery £5444.12 and with battery £9424.12.   6 panels being installed

SELECT CERTIFICATION 1.00

SOLIS RHI−3.6K−48ES 5G DC HYBRID INVERTER 1.00

PUREDRIVE HYBRID DC BATTERY 5KWH 1.00

32 Amp AC Rotary Isolator 2.00

MCS Certification / IWA 2 Year Insurance backed Warranty 1.00

Scaffold / Labour 1.00

John Bergin Roofer 1.00

JA SOLAR JAM54S30−410/MR BF HALF CELL 6.00

K2 2002589 UNIVERSAL CLAMP 1 END BLK SET 8.00

K2 2003072 UNIVERSAL MIDCLAMP 30−42MM 12.00

K2 1004107 RAIL CONN SET SOLID U/LIGHT L 4.00

K2 2003228 3.3M ULTRALIGHT RAIL 8.00

SPAX 0251010600805 6 X 80MM Y ROX W/HEAD 1.00

ECA2.V 1PH GENERATION METER A100C EM111 1.00

SCAME 590.DCGE0416 ISOLATOR DC ENC 16A 1.00

DC Cable 6mm 1.00

Solar Label Pack 1.00

Fire Board 1.00

Solar PV Sundries / Fixings 1.00

100 Amp Henley Choc Block 2.00

K2 Slate Hook / Flange Nut 24.00

100A Wylex Main Switch REC2S 1.00

Solis Wifi Dongle 1.00

2 way 100 amp consumer unit with RCD & MCB / 1 Blank 1.00

LABOUR ELECTRICIAN 1.00

Labour Apprentice 3rd & 4th Year FICA 1.00

If anyone can comment here it would be appreciated, thanks in advance

ABrass

If I'm reading that right you're getting 6x 410 JA Solar Panels with a 3.6kW Solis inverter?

That's a 2.4kW system, which is small but fairly sensibly sized for your low use. However the price is pretty grim as you're paying over £2 per W of panels. Some of that is because it's a small system though and because of the way it works they are more expensive.
Normally I'd say look for more quotes but you're going to have fewer options than those of us in Southern England.

If you decide to go for it then the inverter they've specified can have batteries added later. A smaller ~2kWh battery would be better value for you and most are modular so you can always add more.

If you're rural then you could consider ground mounted panels, they might be competitive and get a larger system which would be better value.

Their payback period is way off. To pay back in 10 years you would have to save £550 a year. You will not get that with your usage. Without a battery you'll use in the region of 30% of your generation and export the rest. A quick guess on generation and use implies more like £200 savings on power you generate rather than buy and £70-£280 for exported power depending on your SEG rate.
 

If electricity prices drop you could be looking at a 20 year payback period. It might not be worth doing 

shaz4473

Thanks for this input.  One thing I learnt when I got my car charger installed is that the electric comes into my neighbour first and is a looped supply.  As it was going to mean taking up the drive to get upgraded (and the drive is a concrete layer with paving look) we did not go ahead .  The car charger was then limited to not overload our system.

Does this have any impact on exporting back to the grid with an old system , looped supply?

shaz4473

ps. can I check do you mean might not be worth a battery or not worth solar panels at all?  thanks

Exiled_Tyke

Why would you have 2.4kW of panels and then a 3.6kW inverter?  

ABrass

shaz4473 said:

ps. can I check do you mean might not be worth a battery or not worth solar panels at all?  thanks

I meant solar. A Battery will never pay back at those prices.

jimjames

shaz4473 said:

Hoping to get some advice on the additional cost of adding a battery as due to my lack of knowledge I can't get my head around why you would not get a battery and store excess power when available and use it when the solar panels are not generating any, this is where you come in!!

If a battery can only store 5kWh of power than that would cost about £1.50 to get from the grid. With a small system that might not be fully charged every day even over the summer so assume you will only get usable battery for half the year say 180 days. That means £270 electricity saving per year from it - but what's the cost? 

You can see the output and how many days are over 5kWh here with 3kWp system but that's SE England with perfectly aligned panels and no significant shading. Further north will be lower.

http://solar-panels-review.321web.co.uk/index.php/yearly-comparison-of-solar-pv

Screwdriva

A few thoughts:

1) Your quoted price is very high as others have shared. What's worse, you've been spec'd budget component brands which, to me would be salt in the wound.

2) Any reason why you've only been quoted for 6 panels? Do you have a Eastern/ Western roof aspect which can accommodate more?

3) Unless you have electrified heating (heat pump), a battery will rarely make financial sense. 

For perspective, a 10 X Sharp 410W panel system + SolarEdge inverter + 10 optimizers + 20+ year warranty on everything should cost no more than £5800. This is what both my installers charge today (sadly neither cover Scotland). 

Hope this helps!

shaz4473

Thanking you all very much ........getting to the point of thinking that solar panels are not going to be a great benefit.

The roof will only take 6 panels as there are dormers in the roof 

Screwdriva

shaz4473 said:

Thanking you all very much ........getting to the point of thinking that solar panels are not going to be a great benefit.

For a 2.5 kW system, you should not be paying more than £4500. At that price, it makes some financial sense.

shaz4473

Thanks for the added info there about the price that it should come in at to make financial sense.  It is something I really wanted to do but for now going onto a back burner!