Ac Coupled and 5 HR Go Faster

Hi all,

Looking into Giv systems and doing some research. I have a 4kw array with solar Edge invertor which I don't want to touch but I would like to add batteries to maximise use of my solar output. I'm on deemed exported.
I'm electric only with ashp for heating and hot water so in winter looking to import at cheap rate over night and utilise batteries in the day.

Based on my calcs for my 5 hour window and an ac coupled invertor I think a suitable combination of batteries would be 2 x 5.2 and 2 x 2.6.

Anyone have any comments on this? Originally I considered 2 x new 9.5 but won't be able to get them to full overnight. Or maybe 2 x inverters and a 9.5 each?

Thanks

s_r_thomas Bear in mind the bigger battery has a warranty for unlimited cycles - I think that's worth having (the smaller ones didn't used to - though maybe that's changed?) Personally if you can afford it (and have the space, and can find any stock!) I'd go for 2 inverters and 2x 9.5 - but remember that tariffs may change, and technically you need an EV to qualify for some. BTW if you fit 2x AC3, do you need G99 approval (because the total exceeds 3.68kW)?

Also there is mention of a higher capacity AC unit coming. 3.6kw I believe. I have an AC3 with 5hr go faster with a single 8.2kw battery and have an ASHP. I do run out of power in the winter months. But its not too bad, the battery charges to full and the house runs off the grid 2130 til 0230 then the battery takes over. At the moment a second battery would be overkill, but I am reconsidering it due to getting an EV and storing more solar during the day and dumping that into the EV over night. But just for home use adding a second battery would only save me £200 - £300 per year max based on my usage data.

Hi,
Thanks for the replies - my potential set-up sounds very similar to THALL . Can you help with a couple of questions:

• Does the battery charge and discharge at 3KW?
• During the off-peak period when battery is charging, does it also discharge too to?

Dual investors would be ideal to cope with over 3KW draw around evening cooking time but I'm not sure that is really warranted - as someone else said here it's all a balance.

s_r_thomas Good morning

Yes the battery charges and discharges at 3KW with the AC3, though the battery can charge discharge faster it is limited by the inverter.

So I use ECO and Timed Timed charge set to my 5hr window. During that time the battery will still discharge to the % you set. So if you set 100% charge then no it will not discharge. If you set 30% it will continue to discharge in that timed window down to the % you set then stop.

I have pondered about cooking etc with just a single AC3 and depending on the efficiency and age of your cooking appliance the AC3 covered most of it. My home is only 2 years old and the kitchen was fitted with better more efficient appliances. In December I used 590Kw from the grid, but total cost was £59, double my double DD.

THALL

Good to know that it does discharge and charge at 3KW and as you say, (my appliances are modern too) it does cover the vast majority of the cooking load. My ASHP I run overnight to heat my underfloor slab up as much as possible and that keeps the house comfortable all day.

I've been reading about the ECO and Timed Charge - can you clarify my understanding:
Off Peak Window starts, battery above say 30% - Battery continues to discharge until 30% reached. Does it charge from grid as well?
Off Peak Window starts, battery below say 30% - Battery charges from grid to 30%.

Eco allows excess solar (what would typically be exported to grid) to charge battery during the day?

Appreciate your guidance

s_r_thomas

Ah now ASHP and underfloor I have found the best result is to leave it on at a set temp all the time. My home has underfloor downstairs divided into 3 control zones. Entrance, kitchen and living room. I keep the entrance at 20c, kitchen and living room at 21c and never turn it off. I found it used a lot less power doing tiny top ups.

Ok the battery should not need to charge during the off peak window. But yes, if it dropped to 29% it would charge from grid back to 30%.
Yes battery will charge from grid back to 30%

ECO will charge the battery from solar up to the limit of the inverter, so with an AC3 3kw of solar max. Anything over would go to the grid if your system is set to export to the grid etc.

No problem, sounds like your setup is just like mine anyway.