Solar panel Newbie, don’t have a clue on prices

lucylou32

I’ve read thru the Martin Lewis recommendations and did the calculator thing, but the results of that, look miles away from the quote I’ve received. I just can’t compare the 2 to see if they’re a good idea for us.. 

can anyone help, see if I’ve done it right…

our postcode is TN9 2HH. We have room for 12 panels, I’m home all day, we’re looking at having 2x batteries 3.2 storage. Roof is 44 pitch, 17 degrees from south. 4.68kWp size, shade factor 1, estimated SAP production 5,208.84. Price includes bird protection enviroguard and scaffolding. £10k. Total. The quote says we should break even in 8-10yrs. But the calculated ML recommend we use, says we’ll only save £400 on energy bills each year, so that’s over 20 yrs to break even ! 

Thanks for any help or guidance offered. (Happy to answer questions if I’ve missed needed info) 

QrizB

You're in the right place to get this analysed for you.

lucylou32 said:

our postcode is TN9 2HH. We have room for 12 panels, I’m home all day, we’re looking at having 2x batteries 3.2 storage. Roof is 44 pitch, 17 degrees from south. 4.68kWp size, shade factor 1, estimated SAP production 5,208.84. Price includes bird protection enviroguard and scaffolding. £10k. Total.

Is this 2x 3.2kWh batteries, for a total of 6.4kWh, or 2x 1.6kWh batteries, for a total of 3.2kWh?

Your 4.68kWp solar PV system would cost around £6k by itself, so the battery is adding around £4k. That's a little bit over the odds for a 3.2kWh battery, but a good price for a 6.4kWh one.

Estimated SAP production 5,208.84. ...The quote says we should break even in 8-10yrs. But the calculated ML recommend we use, says we’ll only save £400 on energy bills each year, so that’s over 20 yrs to break even!

Solar PV suppliers own calculation of payback times are often hugely optimistic and should be ignored.

What's missing from the info is your expected annual electricity use. If it's a typical number of around 3000kWh/yr, and spread roughly evenly across the year at 250kWh/month, with that array and battery conbination you should be able to replace somewhere arouind 2000kWh/yr with solar electricity. That will mean exporting 3000kWh/yr.

At current prices:

• 2000kWh/yr reduction in electricity bill @ 28p/kWh = £560/yr
• 3000kWh/yr exported @ 7.5p/kWh = £225/yr
• Total return = £785/yr, payback time = 12.7 years

However, electricity prices are currently abnormally high and can't be expected to stay this high for all that long. They could easily fall back to roughly half the current level within 2-3 years, at which point you would only be ~£400/yr better off and payback would take 25 years.

Alnat1

The calculator ML linked to is only for solar and doesn't include a system with batteries, so isn't very useful to you.. 

In the end, does it really matter exactly how long it takes, it will eventually pay for itself. You have the certainty that for many years to come your electricity bills will be reduced and you're doing your bit to help the planet.

EcoScruples

The solar part will certainly payback as it has a longer lifespan than the batteries which will need replacing.
In this environment it still makes sense to me for people to do batteries and solar, it just works.

QrizB

Alnat1 said:

In the end, does it really matter exactly how long it takes, it will eventually pay for itself.

and

EcoScruples said:

In this environment it still makes sense to me for people to do batteries and solar, it just works.

I can't agree unreservedly with either of those statements. The effective life of a battery is somewhere around 10 years; if it doesn't pay back in that time, there's a chance it never will.

Screwdriva

QrizB said:
However, electricity prices are currently abnormally high and can't be expected to stay this high for all that long. They could easily fall back to roughly half the current level within 2-3 years, at which point you would only be ~£400/yr better off and payback would take 25 years.

I admire your optimism I expect prices will remain high for the foreseeable. Import at 0.30p per kWh or more and export at 0.15p per kWh or more via the variable tariff. There's no way to know who will be proven correct 5 years from now but it's best to model several prices out to establish an ROI range. 

What's clear to me is that, unless you're expecting blackouts or outages, a battery doesn't make much financial sense unless you're a really heavy night time energy user. This is especially true with the advent of vehicle-to-home charging via an EV.

Until the recent component price increases, a quality 4kW PV system with a 25 year warranty on every component could be had for ~£5K. Payback was achievable in ~6 years or less for many average users using variable export tariffs instead of a battery. 

EcoScruples

QrizB said:

Alnat1 said:

In the end, does it really matter exactly how long it takes, it will eventually pay for itself.

and

EcoScruples said:

In this environment it still makes sense to me for people to do batteries and solar, it just works.

I can't agree unreservedly with either of those statements. The effective life of a battery is somewhere around 10 years; if it doesn't pay back in that time, there's a chance it never will.

Yes fair point, I suppose my statement was more about being good for the environment and not payback which most people look at.
There's definately a feel good factor with having batteries even if they're just about cost neutral but it will depend on how you sweat them. 
I'd be confident that at the current prices of electric you could get an 8 year (ish) payback.

Very important though as mentioned that you know your annual usage, can't do much calculating without that.

Reed_Richards

At this time of year I frequently find myself exporting a lot of energy that I simply cannot use at the time.  If it's sunny I can recharge my battery (6.5 kWh) and my hot water cylinder by early afternoon.  After that even running the dehumidifier and the electric heated towel rail barely dents the amount being exported.  I would feel dreadful if I then ended up having to draw electricity from the grid for evening and overnight use.  So for me the battery is about peace of mind, not about whether the total money it saves me will ever reach the purchase cost.    

[Deleted User]

Reed_Richards said:

At this time of year I frequently find myself exporting a lot of energy that I simply cannot use at the time.  If it's sunny I can recharge my battery (6.5 kWh) and my hot water cylinder by early afternoon.  After that even running the dehumidifier and the electric heated towel rail barely dents the amount being exported.  I would feel dreadful if I then ended up having to draw electricity from the grid for evening and overnight use.  So for me the battery is about peace of mind, not about whether the total money it saves me will ever reach the purchase cost.    

I agree with the above. People buy cars and pay for new kitchens with no thought to a return on investment. My experience of selling a house with PV solar is that it does add value to the home. I accept that an income of over £1000 a year (from FIT) plus energy savings might have been factors. That said, a 4000kWh/year saving from the sun for home use and EV charging plus 2000kWh/year export for my present property would, I believe, positive factors in any future house sale.

2nd_time_buyer

My inkling is that with renewables, we are now in a position where generally what is good for the wallet is good for the environment.

It batteries do not make financial sense at the moment for home storage, then they are depriving other areas where they do make financial/environmental sense e.g. electric cars.

Apologies for my cynism 

Heedtheadvice

I will also add that as well as total annual useage daily routine is one of the other factors. If you are in all day ( like you are ) then you can potentially get more benefit - if you use a good proportion of electricity in that period (rather than exporting it).

If you can not use your own generation daytime (in spring, summer and autumn times really), cannot get a cheap overnight tarriff so need to buy a high proportion more expensively then that changes thing somewhat an favours batteries more for power time shifting.

Without batteries or charging an EV during  the day  then self-using a big percentage of solar generation can be a challenge.

Do at least get some solar but consider if batteries are really for you.

QrizB might be right but I do not share that confidence regarding  prices in the short term, many factors involved but I hope that confidence plays out!