On-grid domestic battery storage

frugalfran

Going away soon, so car will not be used, and am wondering how best to use my tou tariff. Am hoping nightly charges of the batteries means they can be used in the daytime to full advantage, but just wondered if there are any 'tricks of the trade' gathered from the considerable experience of those who post here.  Many thanks

goRt

frugalfran said:

Going away soon, so car will not be used, and am wondering how best to use my tou tariff. Am hoping nightly charges of the batteries means they can be used in the daytime to full advantage, but just wondered if there are any 'tricks of the trade' gathered from the considerable experience of those who post here.  Many thanks

I don't have PV, I use my ToU and run the house from it every day
I do pull 14+ kW when charging the car, batteries, hot water, etc...

Solarchaser

If you are away, id suggest the minimal PV will probably cover most of the battery topping up (assuming no-one in the house) and you shouldn't really need to use the TOU.

This month the batteries were set to full charge every night.... but the main electric user (swimbo) is definitely still in the house.

Managed 21Kw for about a half hour last night.
Batteries, water tanks and the tumble dryer and hair dryer. 😮

jamie07051975

orrery said:

I've just ordered. I've gone for the Lux 3.7kW AC coupled inverter and a single Pylontech US5000 5kWh (nominal) battery, installation and a large cabinet to eventually take a total of x4 US5000's.

I could have got a basic install with x2 US2000 for about £3,700 (fully installed) but I've managed to talk the price up by insisting on the US5000 and 19" rack and will have to pay about £4,600 as the US5000 is special order and not available until November. Ho Hum, but saw no point in not going for the US5000 and making it expandable. I'm estimating that my optimum will be about 15kWh of capacity (my peak tariff usage is commonly 15kWh if the house is occupied, neglecting solar contribution and car charging), but I know that I'll end up with 20kWh to maximise the amount from solar PV in summer). I can buy the additional batteries discount and add them myself.

Can I ask where you have ordered from?

jamie07051975

I've placed an order for our first EV and we'll be charging over night via Octopus Intelligent via an Ohme charger.  As the car will not be at home from about 7am to 5pm we're not going to get it charged via solar so I think that's a non-starter.

However, I do like the sound of batteries charging up off-peak and used throughout the day during peak.  We're generally using just under 10kWh daily.  With the off-peak tariff we'll start to use things like tumble driers and washing machines at night to alter our usage patterns but I think 10kWh of battery should do us and bring our costs down quite a bit.

Ideally it would be installed outside or in the loft as we have no space near the meter/consumer unit.

I have looked at GivEnergy as it can be installed outside.  I presume a loft installation would be cheaper as it would not need to be weather proof.  Just seen Lux inverter plus Pylontech batteries as well and they sound good.

There's just so many different options I'm hoping someone could give me some ideas.

Problem is finding someone to provide and install, basically everyone so far have said they will only do it with solar at the same time which I think is pointless at the moment for me.

Any ideas/thoughts/help would be gratefully received!

Thanks

jamie07051975

goRt said:

70sbudgie said:

There seems to be a general consensus that RoI on batteries isn't good. But on the "how low can you go" board and others, there seem to be a lot of people with batteries that have achieved incredibly low imports. With typical annual import costs currently in the thousands, real world battery RoI can't be all that bad? Am I missing something, or is it to do with the detail? 

I think the logic goes along the lines of:
RoI = ((peak rate - off-peak rate)*90%* kWh per day * 365  * lifetime of batteries) / purchase price

Then
Purchase price * (1 + savings rate%) ^ lifetime of batteries

So your RoI is, say, 1.5, but your initial investment left in a savings account would have grown by 3.5% per year

Then the assumption there's no value in the batteries but you would have your cash

I've got 9.6 kWh batteries that cost 5.2k using about 8 kWh during peak and an EV so on Octopus go currently, I'll likely move to Intelligent Octopus next May

So for me:
RoI = ((40 - 4.5)*90%*8kWh*365*10)/5.2k = 1.79

Savings = 5.3k * (1+3.5%)^10 = 7.3k

Exactly what I am looking at doing with an ROI of around 2.5 years just trying to find a provider/installer for the batteries.

thevilla

Maybe interesting to zappi owners in particular.

https://myenergi.com/libbi/

rgannon45

I found that most installers are wary about the existing installations, especially if they're over 10 years old. Most who we have contacted won't guarantee the work or want to replace the whole system. This is not a problem if you qualify for Eco grants as solar and batteries are now an offered measure.

The only installer that seems to provide a retrofit solar battery solution is Dyson Energy

orrery

jamie07051975 said:

orrery said:

I've just ordered...

Can I ask where you have ordered from?

Green Building Renewables/GoEco Renewables, Daventry for the installed system. Expected install early November. I've now ordered x3 more US5000 batteries, from Voltacon UK, as the prices were just continuing to rise. Delivery end of December. I'll look back in 2 years and see that I've overpaid.

zeupater

rgannon45 said:

I found that most installers are wary about the existing installations, especially if they're over 10 years old. Most who we have contacted won't guarantee the work or want to replace the whole system. This is not a problem if you qualify for Eco grants as solar and batteries are now an offered measure.

The only installer that seems to provide a retrofit solar battery solution is Dyson Energy

Hi

Are you talking to the installers about using the existing panels and replacing the current inverter with a hybrid unit ... or adding an AC connected battery system?

I can see some installers having worries about providing a guarantee for a hybrid based replacement unit as it exposes them to the potential 'my solar's not working, it's up to you to fix it under your guarantee' kind of disgruntled customer argument when it's really an existing panel array problem and nothing to do with the equipment or workmanship they've provided .... there's also the current supply chain problems where batteries in particular are in short supply, this likely causing installers to prioritise installations of battery+solar systems to maximise turnover from the limited supply of batteries they're able to access.

Considering a separate AC connected ESS may help solve the guarantee issue as it should effectively be a completely separate system, however, if potential installers still use the guarantee argument, I'd consider them to simply be 'trying it on' and cross them off the short-list on trust grounds ...

Another consideration is that if you're system is ~10years old it's likely paying a pretty good FiT return, so just be wary of the FiT scheme implications if they attempt to sell any form of system based on replacing the existing panels ... 

HTH - Z