Solar Battery - Yes/No?

Shortsy

Interested in this thread as I've just got my quote for a 3.85 system with optimisers (cost 5.3K) and an optional 5.2kW battery (cost 3.2K). We use less than 2500 electric per year, although planning one 3.5kW A2A pump to cool part of the house in midsummer and to reduce reliance on gas in the heating season. Having used the online calculator for our current use, payback for the panels alone would be about 8 years, when adding the battery it would be about 10 years. The calculator doesn't take into account buying cheaper rate electricity to store and release during the day, but it looks like unfortunately we wouldn't access the cheaper rates anyway as we wouldn't be getting an EV in the next five years (ruling out Octopus Go) and might not even get the Octopus Cosy tariff as our A2A may not get a MCS certificate. So the battery is a marginal decision, it only makes sense if we can fill it from cheaper off peak rates, which it looks like we wouldn't be able to.

Exiled_Tyke

On the other hand, for a more RE world we need more storage (preferably on a huge scale, grid side).  But my tiny green conribution from my battery reduces the grid load at peak times (when a higher proportion of FF is burnt for electricity). 

And the money saving bit?  Like others I thought it might just pay for itself when I bought it.  At current prices it should save me around £600 this year.  It cost me £3k.

94JDH

Batteries are currently saving me just over £200 per month, so in my circumstances wil be beneficial.

ecraig

Shortsy said:

Interested in this thread as I've just got my quote for a 3.85 system with optimisers (cost 5.3K) and an optional 5.2kW battery (cost 3.2K). We use less than 2500 electric per year, although planning one 3.5kW A2A pump to cool part of the house in midsummer and to reduce reliance on gas in the heating season. Having used the online calculator for our current use, payback for the panels alone would be about 8 years, when adding the battery it would be about 10 years. The calculator doesn't take into account buying cheaper rate electricity to store and release during the day, but it looks like unfortunately we wouldn't access the cheaper rates anyway as we wouldn't be getting an EV in the next five years (ruling out Octopus Go) and might not even get the Octopus Cosy tariff as our A2A may not get a MCS certificate. So the battery is a marginal decision, it only makes sense if we can fill it from cheaper off peak rates, which it looks like we wouldn't be able to.

We have a 6.5kwh Growatt battery which can be topped up by grid.. we are now using octopus economy7, which gives us 7hrs until 7.30am at 16p kWh.
You don't necessarily need Go - there are other tarrifs that open up cheap overnight charging.

Since mid September we've saved around £300 based on what the solar panels have produced, plus we have saved around £60 per month in November and dec since moving to economy 7 and relinquishing cheaper overnight charging.

Solarchaser

I'm not sure how, but this thread seems to have turned into a weird thing of people with batteries explaining there reasonings and some their returns, and people who decided against accusing those of us who have of wasting resources... eh???

Anyway I've said this before, so apologies if you have read it before, if you are a low electricity user, say under 2.5Mwh (2500kwh) then battery and inverter costs vs your saving each year will be unlikely to make sense. 
If you are over say 4Mwh a year then you would be borderline, if you have solar, then assuming you pick a storage level that is right for you, and you don't get ripped off, then they should make good sense.
If you are over 6Mwh a year, then they will almost certainly makes sense unless you intentionally skew your figures to make them not make sense. 

However it becomes an individual decision. 
If yours is that you don't want to because of roi or whatever, cool, just don't try and guilt others who have made a different decision. 

So me, personally. I'm an 8Mwh a year user.
I have a useable 20kwh in theory.
In 2022 they discharged a total of 4191kwh.
What does that mean with today's prices?

Well I think it's best to be pessimistic with figures so you don't try and man (or woman) maths it to strongarm it into making financial sense.

So let's say 2000kwh was during the brightest 6 months, and therefor would be from solar and so free. (In reality it will be more was from solar, probably closer to 8 months)
Current average prices for electricity according to the gov.uk site is 34p/kwh
So 2000 x 0.34 = £680 saved

The other 2000 would be bought at cheap rate of 10p/kwh on intelligent octopus. 
Round trip efficiency my battery/inverter package is 82% so 10p/0.82 = 12.2p
So 2000 x 0.122 = £244 (cost to me)
And 2000 x 0.34 = £680 (cost if no batteries)
680-244 = £436 saved. (Intelligent octopus is actually 40p/kwh peak rate, but again trying for pessimistic)

So my saving for 2022 would be £1116

My total battery system was under £7000

So that's all intentionally pessimistic, but still a ~7 year payback

I dont have seg, I have fit, which means I want to self consume as much as possible, others have seg and like to export, fine. Each to their own, calculations would change a bit for seg.

Battery here £1660 for 4kwh useable, 5 of these brings it to 20kwh (or 21.6 kwh in reality) for £8300
https://voltaconsolar.com/pylontech-us5000-lithium-battery.html

Here is a sofar me3000sp for £300, I originally paid £700 for mine.
So say £9k total for the same amount of storage as I have now.
https://www.ebay.co.uk/itm/275636756601?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=MqO40ER1QY6&sssrc=2349624&ssuid=DtbsXk1pRsq&var=&widget_ver=artemis&media=COPY

When I bought my batteries around 4 years ago the advice was to hold back as costs were about to fall, glad I didn't, as costs have risen.

I bought mine partly as a project, partly to be greener, and partly to save money.
Charging off peak when the grid is cleaner, and charging using home generated solar is a whole lot greener than buying electric when the grid is dirtiest.

It works for me, it works for married life as there is no friction about trying to use energy hungry appliances when the sun is out, and it's saving me money, what's not to like?

Power cuts in central Scotland are very rare, and I've only used my eps once, but I was very glad I had it available that once, only house in the street with lights still on.

ispookie666

One thing we all need to consider is, how our electricity consumption will change over then next 5 years. 

Ever since we added 3 A2A heat pumps, our electricity consumption has gone up significantly. The oil heating comes on very very occasionally.  

Weekends we use 25-35kw, weekdays it's around 20-25. The winter months is when my solar underperforms due to shading and split array, hence we rely on E7 to charge up. 

My only regret is Givenergy! 

Reed_Richards

Screwdriva said:

Only the Tesla powerwall has a true household power cut protection (vs. dedicate circuits that are protected by other batteries like the Libbi).  Better than nothing but not quite as imperceptible as we are often led to believe. 

Why do you think that @Screwdriva ?  Firstly, you cannot protect your "household" with a battery unless you consume very little electrical power or you have a larger battery than you would need for any other (domestic) reason.  You can only protect for a limited time so it makes sense to prioritize those circuits you need the most.  

If your house is wired correctly and you have an isolator that allow you to island some or all of your electrical circuits then you can protect those with a suitable inverter and any battery.  But no battery alone can give you the wiring you need.  As I was having my house being rewired, I chose to protect the lighting circuits and a dedicated circuit for my fridge, freezer and router.  If there is a power cut the lights will flicker as the islanding isolator kicks-in but otherwise you might not notice.  It came in handy when we lost power for 24 hours after Storm Arwen but I had to be careful not to run down the battery to the point where the inverter lost power and I could not recharge it.  Fortunately the day after Storm Arwen was sunny.    

Screwdriva

Reed_Richards said:

Why do you think that @Screwdriva ?  Firstly, you cannot protect your "household" with a battery unless you consume very little electrical power or you have a larger battery than you would need for any other (domestic) reason.  You can only protect for a limited time so it makes sense to prioritize those circuits you need the most.  

I have always stated that batteries make little sense for low consumption (<4K kWh) households. As an example, a single 13.5 kWh powerwall can easily power our entire home for 48 hours if it needed to. If the economics ever begin to make clear sense again, it will likely come down to the Tesla's capability or the Libbi's integration (w/ other MyEnergi devices) for us.

Nothing wrong with dedicated circuits, especially if you suffer from repeated short duration outages. It's just not the same thing.

Reed_Richards

@Screwdriva, I was agreeing with you in my previous comment that a battery with enough capacity to power an entire house for 48 hours is likely to be a battery with over capacity for anything else you might want to do with it.  So unless a power failure would cost you a lot of money then a battery that large is over capacity and therefore too expensive.  Maybe Elon needs some support at the moment but you still failed to explain why a Tesla battery is better than all others. 

I bought my battery before you could export electricity at a half-decent rate (although currently only with Octopus).   What price domestic harmony?  The fact that my battery means I don't need to hassle my other half to load-shift all power-consuming chores to a time when the sun is shining is worth a lot of money to me!        

Solarchaser

Screwdriva said:

Reed_Richards said:

Why do you think that @Screwdriva ?  Firstly, you cannot protect your "household" with a battery unless you consume very little electrical power or you have a larger battery than you would need for any other (domestic) reason.  You can only protect for a limited time so it makes sense to prioritize those circuits you need the most.  

I have always stated that batteries make little sense for low consumption (<4K kWh) households. As an example, a single 13.5 kWh powerwall can easily power our entire home for 48 hours if it needed to. If the economics ever begin to make clear sense again, it will likely come down to the Tesla's capability or the Libbi's integration (w/ other MyEnergi devices) for us.

Nothing wrong with dedicated circuits, especially if you suffer from repeated short duration outages. It's just not the same thing.

So you use less than 7kwh a day in the middle of winter?
13.5kwh (easily the most horrendously expensive battery) power wall 13.5/2days = less than 7kwh/ day.
And so taking that 7kwh x 365 = under 2500kwh. For the year

So getting solar must have been a total waste of money for you too.
What roi are you looking at on your panels?