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Topic starter
August 3, 2025 7:58 pm
I’m in California with a 3kW grid-tied system currently under NEM 2.0. I want to expand to 12kW total using the EG4 18kPV inverter and add batteries, but without informing PG&E, since that would push me into NEM 3.0 and incur additional permitting costs.
PG&E already expects about 3kW export during the day. I have two plans. Which is the most secure for ensuring PG&E does not find out about my upgrade?
Plan 1
- Limit PV export to 3kW max
- Absolutely zero export from batteries, ever, even during the day
- No export at all at night
Plan 2
- Block all export completely
- Run the 18kPV in off-grid mode
- Still connect the 18kPV to the main service panel so it can supply loads and prioritize PV
- Allow grid support only when batteries are empty or overloaded, but ensure it never causes even small export back to the grid
Can the 18kPV reliably enforce these limits with export control? Is there any risk of inadvertent backfeed, particularly when the sun is down?
From what I’ve seen in forum discussions, the 18kPV may still briefly backfeed when switching from batteries to grid support. For example, when a central AC kicks on or the batteries run out.
If PG&E detects any export after sunset, that could trigger problems.
This topic was modified 3 weeks ago 3 times by newsolarproject
August 5, 2025 7:16 pm
When the 18kPV is operating in Off-Grid mode, no export to the grid will occur. Additionally, the 18kPV allows you to limit export to PV generation only, if desired.
However, we strongly recommend consulting your local AHJ before proceeding. Making system changes without notifying PG&E could lead to issues down the line.
Topic starter
August 6, 2025 1:57 am
@jared What about when a large load turns off when operating under battery power? Where does that floating current go? There are threads in this forum about people showing hundreds of watts being backfed to the grid when this happens.
August 6, 2025 2:05 am
@newsolarproject you will want to run in off-grid mode and not bother backfeeding. Not only do they pay your next to nothing for your generation but the 18kPV 'leaks' about 200W back to the grid continuously no matter what your settings are except for off-grid.
I ran across this when I backfed to our grid only during peak payment periods and was surprised when my statement shows we were paid far less. When I asked they told me they take every hour when there is ANY backfed power and use the price for that period in the MEAN calculations. So they were taking the MEAN of all 24 hours in the day because the 18kPV 'leaks' back a little power all the time.
Topic starter
August 6, 2025 2:59 am
@dougl Thanks for that tip. I haven't heard of this elsewhere or documented anywhere either.
So when it's in off grid mode, the battery won't backfeed at all, even under circumstances where it uses the grid as support to power 100A loads? I guess that also means solar won't sell at all, period, even when the sun is up at peak angle. So basically I'm not selling to the grid at all and the PV is being "wasted".
This doesn't really matter I guess since utilities pay nothing for PV generation.
August 6, 2025 3:12 am
@newsolarproject I don't think in off-grid mode it would pick up for 100A loads but I don't know since I can live with 50A max load so the grid has been unused for months. And yes, when you battery(batteries) are full the solar PV will throttle back and power your house loads and not backfeed.
I had not found a way to turn off backfeeding through the night and then turn on backfeeding later in the day without the switching bouncing power on teh house/load output. The have a sellback setting but you set it to 0kW and it still pushes that 200W continuously.
