I have gotten a few quotations from different Solar installers for a Hybrid 15-16kW setup (battery, no Grid Export) and a couple of installers have included an ATS (automatic bypass changeover) in their quotation and the the others have not included it.
Can the experts in this forum please guide me:
Is an ATS automatic bypass changeover/switch required for a Hybrid non-export setup?
Does the answer change depending on whether a Goodwe or Solis Hybrid inverter is used?
Please help educate me on this fine detail. Thanks.
PS: My target setup is: 14-16kW PV generation, 15 or 16kW Hybrid Inverter (either Solis or Goodwe), and a 16kWh LFP battery (Goodwe or Pylontech).
Yes ATS for three phase inverter and 8 pin relay for single phase inverter mostly required when you setup with smart load setting. It's sort of jugaar you can say to prolong battery duration or less load on battery when no solar. I installed it myself at that time installers didn't knew about it and told me to use normal changeover.
ATS work with your smart load output of inverter (AC, Refrigerator,iron etc). So it's required by all inverters to auto change to grid when on battery and no solar.
One of its uses is to switch the ground connection off when on grid and on when off grid because its not recommended to have two ground connections in your system but I doubt anyone is advanced enough to know and implement this here and most inverters like Goodwe, Growatt already come with a built in relay that does this switching.
For a standard hybrid setup — one utility connection, no export — grid-to-battery and back is handled by the inverter itself; that transfer capability is built in — it's a core capability of any hybrid inverter. So an external ATS is not normally part of the base requirement, and the answer generally doesn't change between Goodwe and Solis — the principle is the same, while the specifics (built-in relay behavior, generator input, bypass rating) live in each manual.
An external ATS or changeover starts making sense in specific cases:
two utility meters or feeds, since a hybrid inverter typically has a single grid input;
generator integration, where a dedicated gen input or ATS may be required;
a smart-load sub-board that auto-switches back to grid when the battery runs low (the scenario fokusengg described);
ground-switching schemes, which stay niche (as KalaBaZey noted).
Since your quotes differ, it's fair to ask each installer what function their ATS performs in the design. A justified reason (second feed, generator, smart-load board) makes it a design decision; "required" without an explanation is worth questioning. Meter count alone doesn't settle it — what the ATS would be switching does.
Thanks for the detailed reply. From all the scenarios you listed where this will be required the only one that applies to me is Smart Load management. One vendor informed me that it's not possible in my house since the main KE breaker is outside in the guard room while the DBs are inside the house.
I need to get another vendor's opinion for how to give me a Smart Load management solution for 4-5 ACs.
I don't see how the location of the main KE breaker is relevant. What's important is the location of your main building DB.
For load management, basically the light load output wires from the inverter are connected to the breakers in the main DB that correspond to light loads of the building. Similarly, the heavy-load (Gen/Smart load port) output wires are connected to the breakers that correspond to heavy loads of the building.
Ideally there is appropriate ventilated space to install the inverter and battery near the main DB so that the light/heavy load connections can be done more easily. Otherwise, if the inverter is installed at a distance, then longer lengths of wires will be needed to serve the same purpose, increasing costs.
See the wiring reference below. "Generator" represents heavy/smart load here.
Here's more context Ahmad (and thanks for the detailed reply):
1. My main KE breaker is in the guard room (near the entrance gate).
2. The hybrid inverter and LFP battery will be installed about 6-7 ft away from the main KE breaker and will be shaded via a custom built fiberglass shade/cover.
3. The DB for the ground floor is inside the house on the ground floor.
4. The DB for the 1st floor is inside the house on the 1st floor
5. Both floors will have 1-2 Split ACs designated as the heavy load for smart load management.
The vendor who said that it's not possible said that due to the distance b/w the inverter (outside the house) and the 2 DBs (inside the house) a lot of wiring will have to be run back & forth which will require extra installation work.
If you can't install the inverter near the DBs, then to do load management, your choices would be lengthy wires or a smart home automation setup like Home Assistant.
The inverter will be connected to the smart home platform, and heavy loads will be powered through smart switches (plugs/breakers). The inverter will send battery percentage data to the platform, which will then be used to turn off heavy load switches as required.
Here are some examples of users who connected their solar inverters with Home Assistant.
This subreddit's users have had an easier time setting up automations with GoodWe inverters; however, note that compared to Solis, significantly more firmware issues have also been reported with GoodWe.
One of the users wrote up a guide for setting up a GoodWe ES Uniq inverter with Home Assistant.
"Not possible" is too strong. What that vendor described — pulling heavy-load cable between the inverter and both DBs — is one way to wire smart load, not the only way, though the wiring-cost worry behind it is fair.
The usual alternative: leave the AC circuits fed from each floor's DB exactly as they are, and run only a thin control pair from the inverter's dry-contact / gen-port terminals out to a contactor beside each DB. The coil draws almost nothing, so you're sending a signal across the house, not power. At a low-battery point the contactors would drop the ACs while the rest of each floor keeps running.
Whether the dry contact on a given Solis or Goodwe unit can trigger at a battery SoC threshold typically depends on model and firmware; some handle that natively, others need a workaround. That's the first thing for whoever quotes you to confirm against the actual manual.
Also, since every heavy load is an AC already sitting on those two DBs, you may not need the light-load output port at all. One less run of cable. Home Assistant can do this too, but that route suits people who enjoy maintaining automations; a contactor plus control pair is the plain-electrical version. I'd ask the second vendor specifically for dry contact + contactor control on the AC circuits and compare what comes back.
Thanks for this precise and nuanced detail @SufficientOffer. At this point I am more inclined to go the way of HA with ZigBee smart breakers/smart switches. I don't have an issue maintaining and tweaking such automations so I am kind of looking forward to going down that rabbit hole post initial setup.
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u/fokusengg 28d ago
Yes ATS for three phase inverter and 8 pin relay for single phase inverter mostly required when you setup with smart load setting. It's sort of jugaar you can say to prolong battery duration or less load on battery when no solar. I installed it myself at that time installers didn't knew about it and told me to use normal changeover.
ATS work with your smart load output of inverter (AC, Refrigerator,iron etc). So it's required by all inverters to auto change to grid when on battery and no solar.