Batteries capacity

Bluewatersailor · Apr 26, 2024

so this system that in the house we not long purchase as an Growatt which I been told is fault,
Checking the sunny boy inverter it show it putting in around 10kwh at the most per day .
I been quoted for a givenergy Gen 2 at 9.5 kWh
Or
All in one 13.5kwh
As my panels are only max at 10kwh is there any point in putting in a 13.5 gen set as the panel as I see it will never put enough in to fully charge them ,
Or am I missing something and if so what .
Thanks

DIYrich · Apr 26, 2024

Bluewatersailor said:
Or am I missing something and if so what .

You might only have 10kW max to put into the battery, but the 13.6kWh AOI may be able to take out 13.6kW from the battery to power loads.

May not be a smaller AIO that can handle all 10kW from the panels.

Bluewatersailor · Apr 26, 2024

DIYrich said:
You might only have 10kW max to put into the battery, but the 13.6kWh AOI may be able to take out 13.6kW from the battery to power loads.

May not be a smaller AIO that can handle all 10kW from the panels.

Ok I might being stupid but if the panels can only produce 10kw some of that will be used in-house then there never going to be enough to fully charge 13.5 bank .
Or doesn’t it work like that .

DIYrich · Apr 26, 2024

What do you have currently?
You mentioned Growatt and Sunnyboy.

Do you have any batteries?

You mentioned Gevenergy 9.5kWh, and an AIO (plus 13.5 kWh of batteries)?

Seems like you are replacing more than just the Growatt.

If the Sunnyboy has 10kWh of excess power each day (over immediate self consumption), I would go with a 12kWh battery or larger. You don't want to use the full 100% of the battery on a regular basis. At a minimum, you want to save the last 10%, just in case, and the top 10% is "slow" to charge. That said, you may want to use the Grid to charge up the battery so you hit 100% once or twice a month.

Bluewatersailor · Apr 26, 2024

DIYrich said:
What do you have currently?
You mentioned Growatt and Sunnyboy.

Do you have any batteries?

You mentioned Gevenergy 9.5kWh, and an AIO (plus 13.5 kWh of batteries)?

Seems like you are replacing more than just the Growatt.

If the Sunnyboy has 10kWh of excess power each day (over immediate self consumption), I would go with a 12kWh battery or larger. You don't want to use the full 100% of the battery on a regular basis. At a minimum, you want to save the last 10%, just in case, and the top 10% is "slow" to charge. That said, you may want to use the Grid to charge up the battery so you hit 100% once or twice a month.

There’s Growatt 5kw batteries system which so I been told no longer works ,
Then there an sunny boy inverter which goes into the grid FIT .
Photo of today Input just before sun down.
The system recommended is givenergy , we been give two option .
I trying to get my head around if the extra £3K for help bigger 13.5 kw is worth it as the panels are only putting in 10kw max .

DIYrich · Apr 27, 2024

For 10kwh of production, 9.5kwh is probably enough to store one day of production. Some will be consumed immediately, and some will be lost in charging efficiency. If it is winter in your area, summer production may be a lot higher.

kommando · Apr 27, 2024

You are on FIT which gives you very favourable export rates, be very careful you do not lose that. To lose it for storing in a battery with the lose rates of conversion would be an expensive mistake. FIT rates on early installations are up to 72p per kWh. As import rates are much lower why export less at a higher rate than to import.

RPI rate for December has just been released at 5.2% so by my calculations it gives a new FIT rate as below:
Generation rate was 68.3p so now 71.85p per kWh generated.

Check what your FIT rate is.

Bluewatersailor · Apr 28, 2024

DIYrich said:
For 10kwh of production, 9.5kwh is probably enough to store one day of production. Some will be consumed immediately, and some will be lost in charging efficiency. If it is winter in your area, summer production may be a lot higher.

Sorry but I poorly worded that , it’s not the Max I seen at any one time but the max I seen produce in any one day .

shavermcspud · Apr 28, 2024

kommando said:
You are on FIT which gives you very favourable export rates, be very careful you do not lose that. To lose it for storing in a battery with the lose rates of conversion would be an expensive mistake. FIT rates on early installations are up to 72p per kWh. As import rates are much lower why export less at a higher rate than to import.

RPI rate for December has just been released at 5.2% so by my calculations it gives a new FIT rate as below:
Generation rate was 68.3p so now 71.85p per kWh generated.

Check what your FIT rate is.

You can still have battery storage with a FIT system, we fit them all the time. The important bit is it sits outside of the FIT generation meter so an A/C coupled system is required. FIT is based on deemed export normally around 50% of what the generation meter shows. @Bluewatersailor feel free to DM me if you need some advice.

Batteries capacity

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