Sol Ark 15k Setup Question

[bphogenson]

Our home is in Panama, Central America and we have been running a 15.2 KW solar system with two 7.6kw SolarEdge inverters and optimizers, no batteries, for the past four years. The system has been working great on a net meter with the electric company where we get full credit for what we send to the grid. We have not paid an electric bill since we turned the system on. Our problem is that we have a lot of grid down problems and brown our problems that are very hard on our electrical appliances, especially split air conditioners.

We are updating our system to a Sol Ark 15k inverter and 30kw of lithium iron phosphate batteries. We want to set the inverter to use the solar first, then batteries, then grid and finally the Generac generator. We are looking for help on the inverter settings to always have the electricity come through the inverter and limit the brown outs that are normal from our electric company. Is there a way to have the grid charge the batteries when they go below 20% SOC but have the load for the home still come through the batteries rather than direct from the grid? I would like to set up the inverter to always clean the electricity from the grid. Is this possible? Thanks

 

[DIYrich]

You keep the batteries at 80%. Once every week or two, you charge to 100%. System automatically switches to battery when grid down or even brownouts. When grid comes back up, you can recharge from grid, or wait for solar. With net metering, you don't need to use batteries except when grid down.

If you want the inverter to always clean the power, then you need a different system. Sol-ark can charge batteries, control the pv, and generator. Then you need a separate inverter to power your loads. Inverter 2 runs only off the battery. Off-grid growatt may work.

 

[BentleyJ]

You are thinking in terms of a data center type double conversion UPS system that is completely in SERIES with the load, these are somewhat inefficient.
Most hybrid solar back up inverters don't work quite like that. While on the outside of the inverter there is an AC In and an AC out the device appears to be in series with the load but inside the AC (when qualified and the transfer switch is closed) is passing straight through to the loads and if the batteries need charging some of the AC is diverted off to the side, rectified and voltage regulated as needed for the battery. When utility power goes out or gets so "dirty" it is not acceptable, the transfer switch opens and the inverter (which sits off to the side of the AC bus) starts up and provides power to the loads. RCinFLA would be the authority on inverter circuitry or if the Sol-Ark has a true UPS mode. I don't believe so??

What you could do is turn off the AC Input to force the inverter to operate 100% of the time and when solar is insufficient to fully charge the batteries you could use a stand alone charger that just plugs into the wall. It may be possible to partially automate when the stand alone charger comes on using the Aux relay on the inverter based on Battery Voltage or SoC. I'm not an expert on Sol-Ark features and programming options.

 

[Madcodger]

Hoping someone else can chime in here, but would a Victron Quattro be able to handle this situation?

 

[bphogenson]

Thanks for the information. I take away from the discussion would be to add more batteries and thus reduce the electricity coming from the grid. A second option would be to just go off grid, which is not a really good option as the net meter is a benefit to us. Thanks

 

[DIYrich]

Hoping someone else can chime in here, but would a Victron Quattro be able to handle this situation?

Victron Quattro can handle the Inverter side. But you still need a 2nd inverter if you want to isolate from the Grid. Also doesn't have an MPPT if you want to optimize solar panel production.

 

[Madcodger]

Victron Quattro can handle the Inverter side. But you still need a 2nd inverter if you want to isolate from the Grid. Also doesn't have an MPPT if you want to optimize solar panel production.

So here's what I was thinking, but I'm certainly no expert... Could the OP use a separate MPPT solar charge controller (SCC) to handle the battery charging from solar, and simply tie that to the Quattro inverter for management and monitoring via a CerboGX (or even a Raspberry Pi running Victron's free Venus software, which is what I do). Then - and this is where I get fuzzy - could the Quattro be programmed to monitor the quality of the incoming grid power, and simply not use it if it's too far out of a programmable spec? The second AC input could be set up to use the generator if recharging is necessary while the grid is out of spec. I just don't know how Victron handles selling back to the grid, as I don't do that in my setup (and I use a Multiplus, not a Quattro). I also wonder if it may be necessary to use a separate, automated switch to turn on the grid connection to the Quattro only when recharging is necessary, which is what I do (but I don't sell back to the grid).

Anyway, I'm not an expert, but I have been extremely pleased with almost everything about my Victron equipment and find that they build tank-like quality. I'm just not clear on why the second inverter is necessary unless it's just to handle the load required, so if you could elaborate on that (and comment on my thinking here) it might help the OP understand the situation better (and me). Thanks.