Max power from battery?

[Lydanial]

So my setup is the givenergy 5kw inverter and the gen2 9.5kw battery.

When the sun goes down and I'm running on battery how much power should my battery be able to send to the house?

It seems to be around 3.5kw before it then draws from the grid as well?

Also what would be the maximum the solar and battery would send to the house if I was generating 6kw off my panels?

Thanks

 

[Bob Smith]

I don't know that particular battery. If you have the datasheet you can read what its max discharge power is.
The inverter can also be the bottleneck. Even if your battery is capable of let's say 5kW discharge power, your inverter can only handle 3.6

You seem to have a 3.68kW system as this is the maximum you can have with making a request to the DNO (Distribution Network Operator).
Your installer should have explained to you the difference between kW and kWh.

If your battery is full and you have 9.5kWh of stored energy and the battery can discharge at 9.5kW (just for simplicity as your battery won't do that), then after 1h your battery will be flat. However, if your inverter limit to 3.6kW and your house needs 9.5kW (you have the oven, the iron, the kettle, the dryer etc... on), that the 9.5-3.6= 5.9kW will have to come from the Grid.

Many people get caught because they think with a battery of 10kWh and their night consumption of 5kWh they will not need to take from the grid.
You only take from the grid when the house's needs are greater (in power ie in kW) than what your battery/inverter can provide at an instant T

Therefore, understanding means you can avoid turning everything on at the same time. and try not to exceed your limit which seems to be 3.6kW for your case

I hope this helps and I have answered your question

 

[Lydanial]

I don't know that particular battery. If you have the datasheet you can read what its max discharge power is.
The inverter can also be the bottleneck. Even if your battery is capable of let's say 5kW discharge power, your inverter can only handle 3.6

You seem to have a 3.68kW system as this is the maximum you can have with making a request to the DNO (Distribution Network Operator).
Your installer should have explained to you the difference between kW and kWh.

If your battery is full and you have 9.5kWh of stored energy and the battery can discharge at 9.5kW (just for simplicity as your battery won't do that), then after 1h your battery will be flat. However, if your inverter limit to 3.6kW and your house needs 9.5kW (you have the oven, the iron, the kettle, the dryer etc... on), that the 9.5-3.6= 5.9kW will have to come from the Grid.

Many people get caught because they think with a battery of 10kWh and their night consumption of 5kWh they will not need to take from the grid.
You only take from the grid when the house's needs are greater (in power ie in kW) than what your battery/inverter can provide at an instant T

Therefore, understanding means you can avoid turning everything on at the same time. and try not to exceed your limit which seems to be 3.6kW for your case

I hope this helps and I have answered your question

Hi and thanks...

Looking at the battery it states a discharge of 3.6kw... However this doesn't seem to be what I requested from a quote.

I originally requested a 14 panel system with a 5kw inverter and 9.5kw battery so told the solar company I required a g99 as well as I wanted to maximise export in summer.

I understood the inverter would allow me to pull 5kw from the solar and 5 kw from the battery simultaneously meaning that if I had a 9.5kw shower I wouldn't need to use the grid (during the day)... However I was led to believe that in the evening my battery would send up to 5kw and anything over that would be made up by the grid... This doesn't seem to be the case... So is the battery restricted through the battery or inverter?
It's a givenergy gen 2 battery.
https://batteryfactory.co.uk/products/givenergy-9-5kwh-li-ion-battery
They say they've applied for a g98 and g99 as the g98 will be sorted quicker meaning I can get paid for export quicker and then after g99 approval I can 'upgrade' with my supplier.

I understand keeping usage to a minimum, i.e., if we're cooking tea, no showers.. I turn the ac off when I jump in the shower etc...

Have I missed anything?

Thanks

 

[Bob Smith]

From the datasheet I would not say it is a 5kW continuous charge discharge.
You need to take the voltage x amp and it says 80A but the voltage will vary depending on the SoC (State of Charge) so generally the battery is more a 80 * 48 = 3.8kW battery.
It will surely be able to surge above that 80*57=4.8kW but surely for a few seconds only.

The datasheet is quite poor in technical information.

Some brands will say
Continuous discharge 5kW
Max discharge 6kW during 30sec
Peak discharge 7kW during 5sec
things like this

From the info you provided me I cannot read that your system can provide a continuous charge or discharge at 5kW for nearly 2hours (your battery is roughly a 10kWh and the max discharge is not constant during the discharge of the battery so I round up the figure)

I will ask the installer to provide more technical information. To me if you wanted a 5kW continuous discharge then that is not the right battery or you need two in parallel. If your inverter supports this.


Now, I understand that first your installer told the DNO you have a 3.68kW system so G98 is only required then once you have your export tariff, it will make a G99 request. As it is the same equipment I am not sure how that works. Of course, some inverter can have a setting to change the export limit. So maybe he set it to 3.68kW and this is what you now have. After once G99 is approved the limit will be 5kW. So surely your battery will peak discharge close to 5kW but I don't believe this is its normal operating conditions based on what I explained above.

Hope my explanation can help you have a better discussion with your installer and clarify your situation.

 

[Lydanial]

From the datasheet I would not say it is a 5kW continuous charge discharge.
You need to take the voltage x amp and it says 80A but the voltage will vary depending on the SoC (State of Charge) so generally the battery is more a 80 * 48 = 3.8kW battery.
It will surely be able to surge above that 80*57=4.8kW but surely for a few seconds only.

The datasheet is quite poor in technical information.

Some brands will say
Continuous discharge 5kW
Max discharge 6kW during 30sec
Peak discharge 7kW during 5sec
things like this

From the info you provided me I cannot read that your system can provide a continuous charge or discharge at 5kW for nearly 2hours (your battery is roughly a 10kWh and the max discharge is not constant during the discharge of the battery so I round up the figure)

I will ask the installer to provide more technical information. To me if you wanted a 5kW continuous discharge then that is not the right battery or you need two in parallel. If your inverter supports this.


Now, I understand that first your installer told the DNO you have a 3.68kW system so G98 is only required then once you have your export tariff, it will make a G99 request. As it is the same equipment I am not sure how that works. Of course, some inverter can have a setting to change the export limit. So maybe he set it to 3.68kW and this is what you now have. After once G99 is approved the limit will be 5kW. So surely your battery will peak discharge close to 5kW but I don't believe this is its normal operating conditions based on what I explained above.

Hope my explanation can help you have a better discussion with your installer and clarify your situation.

I do know it's a hybrid inverter which can be capped at 3.6kw (although he's told me he hasn't capped it) and then changed to 5kw.

I don't understand the g98/99 situation... Although maybe he's applied as 3.6kw inverter and can then tell them it's now a 5kw inverter (as it's had settings changed)? Thus making it a completely different system...

Thanks for you help, you've basically clarified things for me.

 

[Bob Smith]

I am glad I was able to help. Don't forget the thumb ups