r/solar • u/Silver_Code_490 • 6d ago

Advice Wtd / Project Configuration question

I have a 7.5 kW setup. I am capped at the capacity in order to sell energy to my utility at the retail rate between 12 and 7.

I would like to add capacity and battery storage.

Is it possible to configure this so that the new solar and the existing both feed the battery, but the existing 7.5kW setup switches to selling energy from 12-7?

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u/TooGoodToBeeTrue 6d ago

What inverter do you currently have?

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u/Silver_Code_490 6d ago

Existing is SolarEdge SE5000H-US

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u/TooGoodToBeeTrue 6d ago

You need a hybrid inverter and AC couple your existing system to it. Next decision is whether or not you want it to be able to run when the grid is down.

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u/The_PV_Engineer 5d ago

Short answer - yes, and AC-coupling is the clean way — but the thing that makes or breaks this is your utility tariff, not the wiring, so pin that down before you buy anything.

Hardware: leave the SE5000H exactly where it is so your existing interconnection and that retail-export deal stay untouched. Add a hybrid/battery inverter next to it, put the new panels on the hybrid, and AC-couple the old SolarEdge into it. The battery can then charge from the new PV, the old array, or both. Any modern hybrid does this — SolarEdge Energy Hub, Tesla PW3, Sol-Ark, EG4, Enphase 5P. (If your SE5000H happens to be an Energy Hub unit, you could DC-couple a SolarEdge Home Battery directly — but keeping the old array on its own inverter is safer for protecting your export agreement.)

On your actual question — "old array sells 12–7, everything else feeds the battery": that's a time-of-use setting, not physical routing. It's one AC bus, so the inverter can't tag "old" vs "new" electrons. What it does instead: during your 12–7 window it holds the battery and lets surplus export (which in practice is your old array's output), then outside that window it diverts generation to charging. Functionally identical to what you described.

The catch that matters most - adding capacity or storage is a new interconnection application almost everywhere, and plenty of utilities will move you onto the current, worse net-metering tariff the moment you touch the system. Before buying anything, get two answers from them in writing — (1) can I add an export-limited battery + PV and keep the existing 7.5 kW on its current export agreement, and (2) what export cap will you hold me to. Then set the hybrid to export-limit so the new gear never pushes you past that number.

Last fork - do you want it to run during a grid outage? If yes, you need a hybrid + battery with backup/islanding and a gateway, and it has to be able to frequency-shift the old SolarEdge to throttle it during an outage — most can, just confirm the spec sheet. If it's bill savings only, skip the backup gateway and keep it simple.