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My little grid tied system with tesla batteries
#21
Jens, I have overlooked your response Smile ..but in meanwhile I have solved the issue I had with the system.
It works now as charm.. except the fact that discharge of batteries can't pass 40.9 Volts.. I was wondering where this limitation is coming from.. but it would be related to ESS configuration.. my guess.

This way my system has min Volt at 40.9V and max. Volt at 49.2V.

Regarding durability.. I would more worry about charging too high than discharging too low. Having an option to discharge lower than 40.9V would be nice to have.

Dropping some photos:

Note: fronius and victron are in different corners of the garage


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#22
(03-26-2020, 05:02 PM)jaro2k Wrote: Jens, I have overlooked your response Smile ..but in meanwhile I have solved the issue I had with the system.
It works now as charm.. except the fact that discharge of batteries can't pass 40.9 Volts.. I was wondering where this limitation is coming from.. but it would be related to ESS configuration.. my guess.

This way my system has min Volt at 40.9V and max. Volt at 49.2V.

Regarding durability.. I would more worry about charging too high than discharging too low. Having an option to discharge lower than 40.9V would be nice to have.

Good morning !

Something seems to be wrong with "new message notification". I also dont get any.

Regarding ESS and 40.9 Volts: it's an Inverter Limitation. Victron lowered this by 1 Volt a year ago via firmware update.

Please have a look at: https://community.victronenergy.com/ques...on-in.html

Seems to be not that easy to lower further than this value.

Which BMS do you use ? Does not look like a simp bms ?

I'm fine with my voltages. High Cell limit (float) is 4.106 volts. Lower limit aus mentioned before is 3.408 volts.

BMS will disconnect the charger if one cell reaches 4.160 Volts (quite in a secure range).

Please find attached a chart from a tesla forum. As one can see: disconnnecting at 20,45 volts (on single pack basis) is very close to the final voltage drop at the end of the discharge process. This voltage seems to be a perfect sweet spot.

Love your Fronuis Storage Wink .....

Jens

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#23
so,  you are right. ..that's about 15%-95% (SOC) range. No reason to seek for change. Anyway, thank you for link.

Regarding fronius battery.. I had to tweak this setup a bit.. I have 2 smart-meters at the front: one for fronius and one for victron.
right now, the victron ess is charging first and if generated solar power exceeds 3.2kW (70A limit na charging) the surplus goes to fronius battery.. Also ones victron ess is 100% full.. energy goes to fronius battery.

I'm thinking to extend current setup with additional DC-coupled solar panels (to victron ess).. but will need to read about it.. how to do it.

Regarding BMS.. I was considering simpBMS but then I decided to go for BPath BMS.. it's a great product well integrated with victron inverters.
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#24
very nice project, I'm following.
vitron and tesla bricks are already here, await awaiting to find a connection.
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