Help with Enphase solar + separate battery

[jdlongenecker]

Hello everyone!

I've been looking into solar for the last few years, but with the tax credits ending I am looking to pull the trigger. With our shading pattern, I believe microinverters make the most sense (also the main company that has quoted solar uses Enphase)

I was thinking of feeding the 8kW of AC coupled solar into an EG4 18kPV hybrid inverter with ~15-30kWh of battery connected--essentially like the EG4 diagram attached, except I was hoping to run the entire home panel off the Load terminals on the inverter. I realize that in a power outage scenario, the inverter couldn't supply enough power to run 200A, but from the last few years of power consumption data off of my Sense home energy monitor, the only times I get close to 40A/10kW of power draw is when the dryer runs and the air conditioners are running at the hottest part of the day.

Is that allowed code wise? does the 18kPV have its own internal protections if over 50A of current was drawn from the load inputs during off grid operation during a power outage?

Finally--the other option is to add on a Tesla Powerwall 3 when the solar company installs solar panels. The up front cost per kWh of getting an 18kPV and 15kWh battery is likely about the same as getting a Powerwall 3--but then I really like the ability to add 48V batteries down the road as electricity gets cheaper.

Thank you all for your help!

 

[DIYrich]

Grid down, the 18kpv will shut down if you exceed the inverter capacity (50a). But, that is in addition to whatever the enphase is producing.

 

[SplitUniverse]

Look at the recommended DC to AC coupled ratio.
If you don't have "enough batteries" the 18kpv might cut off the micros at high SOC (solark does).
Your plan is workable (similar to what I have with a Solark) but you probably want more batteries if you are to keep the micros producing during high load Grid down scenarios (when a large load drops and the BMS demands lower charge rates the inverter doesn't have time to bump the frequency to curtail AC coupled micros so it just drops them).
Basically you'll have to do some load management during power outages but I guess that is a given for most people (if you realize that the Grid is down, under most circumstances you will not even know about it).