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Hybrid Inverter - Advice Choosing the Right One

glandpuck

Solar Enthusiast
Joined
Aug 26, 2023
Messages
421
Location
San Diego
I need some real world advice on choosing a new hybrid inverter for my situation. This is my problem:

1. My PV array is 8k in size.
2. My lithium battery bank is 40 kW in size
3. My grid tie is only 50 amps @ 240 volts
4. MY LOADS ARE ALWAYS LARGER THAN MY PV PRODUCTION.
5. My generator supply is about 40 amps @240v.
6. My electricity plan is based on Time of Use with rates cheapest Midnight till 6 AM weekdays, until 2PM weekends and costly 4PM till 9PM.
7. I have an electric car too on this circuitry as well as an electric dryer.

My 24 hour day of PV and load use looks like this:

Midnight until 6AM, I like to charge the EV and try to AC charge my batteries and my baseline load aside from these is about 2 kW. If running the AC, this adds about 1.5 kW to baseline. I can change the EV charging amperage on the fly in real time so I usually set it for 15 amps and never go above 25 amps. I try to keep the total load pulled from the grid to 8.6 kW so as to avoid tripping any breaker. At a draw of 8.6 kW, the AC voltage drops from 240 to about 233.

At 6AM, charging stops on weekdays. The system can use either AC or battery until PV starts at around 9AM now. The load from 6AM until 9:30 AM is about 2 kW. At 9:30 AM until 4 PM, pool pumps operate and go through their cycles. They add about 1 kW to base load and then the cycling pumps for spa, slides run for 10 minutes daily and add about 2kW. So during those periods, load is 5.5 kW. Any AC running during the day adds about 1.5 kW to baseline load.

During the daytime, PV ramps up on sunny days to about 6kW. Sunny day PV runs from winter lows of 24kW to summer highs of up to 50 kW.

At 4PM until 9 PM, I want the system to run off batteries to avoid high time of use rates.

From 9 PM until midnight, I am okay with batteries or grid use or a mix of both.

My old inverter was an Outback Radian and it would allow me to use grid power and battery power to my critical loads panel at the same time, so the inverter could output up to 8k with the batteries and add grid too. I would be able to run loads of up to 12k with this passthrough setup. Never a hiccup or any loss of power. As the batteries discharged, the AC grid tie increased to meet demands.

What I found in trying to use a popular hybrid inverter on this sight that it was grid + PV to loads, but never could combine grid and batteries to load. It was a switch back and forth from one to the other. And this was causing power outages. And it had all kinds of problems if trying to charge batteries from PV and AC source at the same time. This type of inverter limited me to no more than 8.6 kW to be safe.

SO I AM LOOKING FOR A HYDRID INVERTER THAT CAN COMBINE OUTPUT TO LOADS FROM GRID AND BATTERY AT THE SAME TIME SO THAT SWITCHING POWER OUTAGES THAT RESULT FROM ONLY BEING ABLE TO USE GRID OR BATTERY SEPARATELY DO NOT HAPPEN. MY RADIAN DID THIS. ARE THERE ANY OTHERS THAT CAN BE USED?
 
Eg4 18kpv. Sol-ark 12k or 15k.

I know with the Sol-ark you can tell to limit grid to 50 amps, and it will supplement from pv and battery.

If you can get a good price for exporting, I would charge up the batteries overnight. Export the pv when generated, and between 4pm-9pm use pv and battery first.
 
Last edited:
To my knowledge the EG4 18k PV will not blend grid power and battery power to a simultaneous output. It will transfer back and forth between the two separately. Will combine battery and pv to loads, but not grid and battery to loads.
 
To my knowledge the EG4 18k PV will not blend grid power and battery power to a simultaneous output. It will transfer back and forth between the two separately. Will combine battery and pv to loads, but not grid and battery to loads.
Do you know if the SolArk 15K combines both?
 
No, that's what I am trying to learn. My Outback Radian could do this, but I would need 2 in parallel and it is still low voltage charge controllers. I may wind up having to go back to it. Never had an outage with it.

If Sol-Ark can do it then I will go that route.
 
Do you know if the SolArk 15K combines both?
yes. It has "Grid Peak Shaving" mode, which is a variation of it.

"Grid-Peak Shaving: Sets the Sol-Ark's threshold to begin contributing power from batteries to keep the power drawn from the grid
of generator connected to the “GRID” terminal, below that value."

"Limiter
The Sol-Ark 15K-2P-N inverter will simultaneously utilize different available power sources to satisfy load demand in the electrical
service panels (essential loads panel / main service panel). The following work modes allow the user to determine how generated
power is utilized."
 
To my knowledge the EG4 18k PV will not blend grid power and battery power to a simultaneous output. It will transfer back and forth between the two separately. Will combine battery and pv to loads, but not grid and battery to loads.

Page 75 of 18kpv manual:
"11.1.2 Charge First ModeThe order of priority for solar power usage will be Battery>Load>Grid. During the charge first period, loads are first supplied power from the grid. If there is excess solar power after charging batteries, the excess solar will power the loads along with grid power."


Page 76 of 18kpv manual:
Grid peak-shaving and peak-shaving
power (kW):
Used to set the maximum power that the
inverter will draw from the grid. See page
84 for examples.
 
Okay, on the 18k inverter, grid peak shaving works to limit the amount of grid power that the inverter will draw from the grid AC input. So for example, if your load from high TOU period is 3kW and you set the grid peak shaving to 1 kW, this means that for that time period, the load will be powered by battery and or PV, but no more than 1kW from the grid tie. If your batteries go below the set SOC or Voltage, this is where you can run into trouble due to switching from battery to grid entirely.

As far as the Charge First PV mode, you can set times of the day for this to be in use. Say suppose you want batteries to charge from PV first, you can set a timer say from 9 AM to 1 PM in the daytime. Or just forget the timer and set a voltage or an SOC.

In my setup, when I tried to set charge first PV by SOC or time, it didn't always work. Also, when I told it to charge with AC power from midnight to 6 am, limit charging to 3kW rate and stop at SOC 80%, the inverter either would not follow the commands or would throw E019 bus over voltage errors and the charging would not take place. I reached the point where support told me to only charge with PV and not charge with AC, but then when batts got low at night, system powered off rather than switch to grid support.

I'm just saying.....
 
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