ESS: Setting at Optimized (w/ battery Life), but MPPT does not supply together with Grid

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JimV asked Apr 15, '21

ESS: Setting at Optimized (w/ battery Life), but MPPT does not supply together with Grid

Hi everyone.

Our set-up:

Quattro with 400AH, 48VDC lead acid batteries, Smartsolar 250/100 with 4kW PV.

ESS set-up, load is a water pump consuming around 5kW. We set it on Optimized w/ Battery Life. Min SOC @100%, Active SOC 100%.

However, the batteries get discharged and supply the load together with the PV, with the Grid only on standby (only around 100W which was the grid setpoint).

Then when battery SOC reaches around 97%, the Grid supplies the load entirely (passthru) and the PV only charges the battery. When the SOC reaches almost 100% , the PV output is only around 1kW, even though the sun is up and we are expecting a high output from the PV.

The systems remains in this condition, with the grid supplying the load and no PV power supplementing the grid.

We also tried Keep Batteries charged. But still the same. Only the grid supplies the load and the PV only charges the battery. BUt when the SOC is already 100%, the PV output is very minimal and only supplies the battery at float charge.

Hope anybody can give us any idea why this is happening.

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Answer 1 · 2021-04-15T08:04:36Z

marv2097 answered · Apr 15, 2021 at 08:04 AM

Hi @JimV,

It sounds like you are telling the system to only use power if the grid fails, is that what you are aiming for?

I am still new to this myself but I would have thought you would have min SOC set to something like 20%, This way up to 80% of the battery capacity can be used for supplying the load and 20% is reserved for the grid being down.

I dont use battery life as I have no solar currently so you may want to try this "without battery life"to test. See the explanation here: https://www.victronenergy.com/media/pg/Energy_Storage_System/en/configuration.html

Cheers

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JimV commented · Apr 15, 2021 at 09:23 AM

Hi @marv2097,

Thank you for your input.

Actually we do not want to use the battery. It is just intended for grid failure, which is common in the site.
We again tried using the "Keep batteries charged". Initially, it was already working fine - the PV was both charging the battery and giving part of its power to the load.

While we were observing the operation of the system, the grid went down for a few minutes. The PV and the battery then supplied power to the load, just as the system is expected to do.
However, when the grid came back, the battery and PV was still supplying the load with the grid only providing a little part to the load.
The load was around 5.5kw. The PV was supplying less than 1kW (it was already late in the afternoon) . The battery was supplying around 4kW and the grid was only contributing around 500watts.
It continued for more than an hour. The SOC went down to 89%. Our technician stopped it for now since it was already late and needed to leave the site.

We were expecting that the battery would stop supplying the load when the grid comes back.

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