Trying to work out if Solar and Battery will save money.

majorstare

Hope you can help.
I am trying to work out how much a solar and battery storage system would potentially save me per month.

Had a quote for 16x JA Solar panels (375W), XSolar inverter and 5.2kw Fox battery. This creates a 5.84Kw system.
Price - £10,995 installed.
From the survey, it is expected to produce a minimum of 5285Kw per annum. Front of house is south facing and gets sun all day, no shading. Location NG17 7HB.

I am on Octopus Go (23.7p day rate, 5p for four hours at night).
According to the Octopus app, we have used 8815Kw in the last 12 months. Although it doesnt show the split from day/night.
We have a 100% EV car charged about once a week and a PHEV charged 4-5 times a week, at cheaper night rate for 4 hours.


My tarrif with Octopus ends October, i dread to think what the new tarrif will be. So im trying to future proof the next few years.

So im trying to calculate how much of a saving per month i will "make" with the proposed system, including the battery storage.
I am not paying cash for this, it will be a loan, costing about £150/month.

Many thanks.

Solarchaser

Your system is 375 x 16 so 6kw system
That should be around £6-7k at current prices
The battery being 5.2 is essentially two of these at say £2k being generous 
https://www.itstechnologies.shop/products/fox-hv2600-2-6kwh-hv-battery-incl-brackets

So I think the quote is a little high, and I'd suggest getting quotes from other places.

They are a 90% dod battery so useable is just under 4.7kwh
I've never heard of fox until now, but seems like a good battery, similar in size to the pylontech many of us have, but with a much higher discharge rate, in fact double the pylontech. 

I can't find anything about an Xsolar inverter.
I'm gonna guess its a 5kw inverter,  which would seem OK against a 6kw array, if they have actually quoted you a 5.84kw inverter,  that would seem a little big for a 6kw system,  but probably fine.

The 5.2Mwh /year seems about right for south facing in london, but you are a bit further north, so maybe 5Mwh, other users from closer to you will be better able to inform.

You are a high user, so I think like myself, you will benefit from batteries, especially batteries powered from solar, but that somewhat depends on how your usage is spread.
If most of it is during the day, then might not be worthwhile getting batteries,  if its mainly in the evening then 4.7kwh won't make much of a dent,  a balance of both and you are maybe about right.

If you look at your octopus electric bills, they will tell you each month how many units you bought at the cheaper rate and how many at the more expensive rate.
Your smart meter will also show your different rates, for me the cheap rate is the first figure.

As to how much you can save, that's very individual, but hopefully this thread I updated recently will give you some insight.

https://forums.moneysavingexpert.com/discussion/6311640/home-batteries-can-save-you-money/p3#latest

2nd_time_buyer

Solarchaser said:

Your system is 375 x 16 so 6kw system
That should be around £6-7k at current prices
The battery being 5.2 is essentially two of these at say £2k being generous 
https://www.itstechnologies.shop/products/fox-hv2600-2-6kwh-hv-battery-incl-brackets

Looking at prices that people have been quoted around here recently. I would concur that the price is a little high but it is not outrageous.

Pigeon mesh is generally recommended on here. Unless you are sure it won't be a problem. 

With your high usage. I would ask the question of whether they can fit any more panels on? And/or what the cost would be of upgrading the panels to higher powered ones would be (400w+).

In terms of generation estimation, it is worth putting it in to the PVGIS but it looks about right 

https://re.jrc.ec.europa.eu/pvg_tools/en/

Magnitio

Are you able to charge the cars during the day from solar? It won't make sense to charge your cars from the battery; it's too small and the charge/discharge losses could actually make it more expensive than using off-peak electricity (at 5p) and selling surplus solar (at 4.1p).

However, rates are changing and the difference between peak/off-peak may well reduce, so it is difficult to predict an accurate ROI. A lot depends on whether you are able to shift your consumption to the hours of the day when solar power is being generated, unless you have a larger battery. On a day like today, that battery could be filled within a couple of hours.

With current prices of solar/battery installation, the ROI is generally easier to make for solar than solar/battery. As battery sizes increase and prices reduce, the case will hopefully improve.

Based on your loan cost of £150/month, I think the answer is likely to be no; that equates to using 100% of the solar energy produced at a rate of 34p/kWh (5285*.34/12). I know there are savings to be made by charging the battery at off-peak, but you will never get near using 100% of your solar output.

arty688

if you took your cars out of the equation as they are off peak . I would say you were a low user so batteries are probably not worth it.

QrizB

majorstare said:

So im trying to calculate how much of a saving per month i will "make" with the proposed system, including the battery storage.
I am not paying cash for this, it will be a loan, costing about £150/month.

I guess your current electricity bill is around £1200/yr, £100/month?

My wet-finger estimate, based on your current Go tariff, is that you'll save around £700/yr. That's simply assuming you''ll be able to cycle the battery every day (using Go in the winter, solar the rest of the time) plus offset your daytime energy use with solar for 9 months of the year, and assuming you export the surplus to Octopus at 4p/kWh.

Savings will increase to around £1000/yr if you move onto the currently-offered Go tariff of 35p peak / 7.5p off-peak.

On the other hand, if electricity prices drop back to expected levels, your savings will fall too.

majorstare

Cheers all.

My wife works at home during the day but her energy consumption is pretty low, unless its chilly when she uses an oil radiator to take the chill from her work cabin. Big appliances like tumble dryer, dish washer and clothes washer can be used at any time if needed as they have timers.
Her car can also be plugged in at any time, mine only when i get home from work.

Looked at the figures today and i think we will wait untill later this year, see what happens with tariffs and energy prices. My Ocotpus tarrif is locked till November 27th.
We will also have in January 2023 more income per month and a better position to do this rather than a loan, so better in that respect.

However, there might be a possibility of battery storage rather than panels and using the Go tarrif at 5p/Kwh to reduce monthly energy costs.