question

monachus avatar image
monachus asked

How do I only use the grid for PV backup when SOC is below 40%?

Hello, everyone! I live in Chile and recently had a company install 5 kWp of PV and 625 Ah of battery backup at 48V.

The installer told me that the system would use PV when available, but if the battery SOC fell below 40% and PV was at 0 (e.g. night), it would pull from the grid until SOC was above 50%. This way we're only using the grid if we need to, for the least amount of time, and never cycling the batteries below 40%.

It's not working as expected.

When capacity falls below 40%, grid usage stays at 0. I call him, he logs in and makes some change, and it starts pulling from the grid. Then it'll climb above 50% without turning off. I'll call him, he'll make some change, and it'll stop pulling from the grid. I can find the lower limit parameter, but I'm not able to find the upper limit in the configuration. I'm starting to think he's doing this manually.

We live at the end of the line in a rural area, so our grid voltage is unreliable and fluctuates between 205 and 250 throughout the day. In addition to the configuration for when to pull from the grid, I'd like the inverter to accept grid voltage between 205 and 245V so that there are only a few hours out of the day where it might not be able to pull from the grid if it needs to. I'm not able to find that parameter either, but he has sent me screen shots of the web portal that show it exists.

The inverter is a Quattro 48/8000/110-2x100.

What parameters do I need to set in order to get the result that I'm after? If you can tell me what to look at, and whether I can get to it through the panel or if I need to access it through the web portal, I'll be able to verify his settings and figure out where the disconnect is (no pun intended).

Thank you!


batterySOCgrid
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1 Answer
tilo avatar image
tilo answered ·

As far as I know there is no configurable upper SOC limit to end the grid charge which is activated after you get to the lower limit SOC, at least not straightforward without tricks. This is mainly because it is not necessary. In the ESS setting the system will stay at the lower SOC limit and cover the consumption from the grid, without recharging the batteries (exception: sustain mode). If you define a lower SOC limit for discharge, why would you want to first discharge the battery to 40% and then in the same night recharge with the grid to 50%, instead of waiting till the next day for solar to recharge? If you want to keep 50% in your batteries, use that as lower limit.

In ESS there is an option called "scheduled charging" which allows an upper SOC limit, but that is activated regularly based on time, not if you reach a low SOC. This is intended for peak shaving/avoiding peak tariff hours during certain hours in a day, not for your case. Try ESS in mode Optimized with Battery Life algorithm.

Can you list all the system components please with their firmware version? Use the latest firmware in all components.

Do you use the ESS assistant? If you use ESS, please post a screenshot of your ESS configuration.

The accepted AC input voltage range is configured in the Quattro with the software VE Configure 3, through a MK3-USB or through VRM remote configuration. If you use ESS: The ESS setting requires a grid parameter setting to chose in VEConfigure3 in the Grid tab, even if you do not want to inject energy to the grid. Right now I am not sure if the AC Input voltage range configuration of the Quattro in the same Grid tab in VEConfigure3 overrides/narrows the ESS grid parameter setting range. Unfortunately there is still no parameter set for Chile, so you might use "Other".

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