Bogdan Nedelcu avatar image
Bogdan Nedelcu asked

Software attenuation for home excess PV charging of EV while keeping ESS battery consumption minimal

I work with an EasySolar II with 4x12V Deep Gel batteries of 220Ah each. The ESS is connected in parallel to the grid and a power meter is mounted single phase and connected to the ES USB port. Solar PV give max 4000W power so not enough for the 7KW need of the standard single phase charger of the EV.

Charging EV is a pain as it draws a lot of power from the batteries even in cases of maximum PV power available… I am at -3000 KW, not considering the house consumption averaged at 1KW.

In order to prevent discharging the batteries during the charging of the car I setup a script which monitors the power drained from the batteries and adjust dynamically the Grid Setpoint in order to reduce to minimum the previous value. This way the ESS raises the power taken from the grid and no longer needs to supply it’s own power from batteries. I do a running average to smooth out all the values and update these parameters every second and leave -50W as a buffer for the PV panels to step in if more solar is available.

The results look promising as I have maximum 10 seconds of ESS powering the EV from batteries until the running average catches up, then system stabilizes at -80W at battery, all the rest comes from the PV.

Not only this is usable for EV car but also for large consumers in the house, as in bad weather they cannot be charged from PV so battery draining is probable.

Not sure if this is appropriate usage of Victron, or if other options are possible for my setup… I leave the thread as a request for your comments.

Registers used: 2700 to write grid setpoint, 810 for Grid Input L1, 842 for battery load.

Download from this link and use it on your own risk

/var/log/evvictron.log where the logging goes.

Script should run directly on the EasySolar through ssh.


ESSEasySolar All-in-Onesolarvictron
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Alexandra avatar image Alexandra ♦ commented ·
@Bogdan Nedelcu

Neat. I am sure there will be a few Victron users who would be interested in this script.

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2 Answers
Bogdan Nedelcu avatar image
Bogdan Nedelcu answered ·

Quick update: I activated DVCC and selected "Keep batteries charged" in ESS Settings. While I charge the EV car with 4KW, higher than what PV produces, the system takes few Watts from battery, mostly when new consumers appear or disappear.

For whoever is parallel connected to the grid, I think this is the best configuration which does not empty batteries when a EV car is charged from a EasySolar system.

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Jonathan Simpson avatar image
Jonathan Simpson answered ·

@Bogdan Nedelcu Would one be able to use a similar script to lower the Grid setpoint during the day as PV can handle the load, and at night raise the setpoint to reduce the battery ?

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Bogdan Nedelcu avatar image Bogdan Nedelcu commented ·
@Jonathan Simpson you should change the setpWDefault variable inside the loop based on the current hour.

However I discovered that if I enable DVCC and turn to "Keep batteries charged" the system does exactly this. Keeps a constant voltage of the batteries thus they do not discharge during night and during day the power is extracted from PV. No matter if you give excess to network or not.

Any other mode for ESS (Optimized/not optimiezed) behave strange when batteries are discharged, meaning that sometimes PV is working at 1% in full suneshine and keeps the batteries in Absorption for hours, not giving power to house. Basically I think I have a too small battery pack for my household consumption in order to cycle them daily.

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