GoodWe ESA backup: what happens in a blackout

Quick answer: when the grid fails, the GoodWe ESA disconnects from the network and runs your backed-up circuits, or the whole switchboard, from the battery and the solar panels, switching over in under 4 ms. Its internal 63 A bypass means whole-home backup needs no separate gateway. In backup it supplies 10 kVA on the 9.999 kW models and 15 kVA on the 15 kW model, with short surges of 20 and 30 kVA for 10 seconds.

GoodWe ESA backup is built into the unit rather than added on. In its Australian launch release, GoodWe said that unlike many hybrid systems that rely on additional gateways or accessories, the ESA provides 63 amp full-home backup from day one. Our guide to whole-home vs essential-circuit backup explains both approaches in general; this page covers how the ESA does it, on the single-phase GW9.999K-EHA-G20 and the three-phase GW9.999K-ETA-G20 and GW15K-ETA-G20.

How does GoodWe ESA backup work?

The ESA has two AC connections: a grid port that connects to the network, and a backup port that feeds the circuits it protects. While the grid is up, power for those circuits passes through the unit on an internal bypass rated at 63 A, so the house runs normally and the inverter adds solar and battery power as needed.

When the grid fails, the ESA opens its built-in grid relay, so it stops feeding the network, and supplies the backup port from the battery and the panels. GoodWe rates that switchover at under 4 milliseconds, quick enough that most appliances ride straight through. This is what GoodWe means by “UPS-level, full house back-up (63A) with no gateway needed”: the switching that some systems put in a separate box is inside the unit.

How much can it run in a blackout?

Two ratings matter, and they are easy to confuse. The bypass rating is what the house can draw through the ESA while the grid is up. The backup rating is what the ESA itself can supply once the grid is gone.

So “whole-home” means every circuit stays connected, not that everything can run at once. The 10-second surge rating helps with motors that draw extra power for a moment as they start, such as fridge compressors and pumps. But a ducted air conditioner, an oven, a kettle and an EV charger running together can exceed 10 kVA, and if the load goes past the backup rating, the inverter’s overload protection steps in. We design the backup around the loads you want to keep running.

What do your solar panels do during a blackout?

They keep working. GoodWe’s Australian manual for the three-phase ESA describes the off-grid mode this way: when the grid fails, solar first supplies the household loads during the day and any surplus charges the battery; at night the battery supplies the loads. GoodWe describes the series’ off-grid mode as allowing independent power supply with solar, and the single-phase datasheet rates its off-grid output at 10 kVA, with 20 kVA for 10 seconds.

That matters in a long outage: a sunny day can refill the battery while the grid is still down, while a cloudy winter day may leave little to spare. The three-phase manual adds two details worth knowing:

• Black start. If the grid is down, there is no solar and the inverter has stopped, the battery can restart the system. With the battery power switches on, a 15-second wait and then a 2-second press and hold of the multifunction button on any battery makes the battery discharge, starts the inverter and puts it into off-grid mode.
• A floor under the battery. For systems running off-grid, GoodWe recommends setting a lower charge limit of 30% so the battery isn’t drained completely, and says the system limits loads or goes into protection mode as it nears that limit.

Whole house or selected circuits?

GoodWe’s three-phase manual shows two wiring arrangements for Australia: whole-house backup, where all household circuits are fed from the backup port, and partial backup, where only selected circuits are and the rest stay on the grid side. GoodWe markets the single-phase ESA for full-house backup through the same 63 A bypass.

Whole-house is the simpler experience: everything stays connected and there is nothing to remember. Partial backup can still make sense on a three-phase home where a few very large loads, such as a ducted system or an EV charger, would otherwise push past the backup rating or drain the battery quickly. Which arrangement suits your switchboard is settled at the site assessment, and the backup question in Build Your System is there because the answer changes the equipment and the switchboard work.

What limits backup in practice?

• Power. The backup rating caps what can run at once: 10 kVA on the 9.999 kW models, 15 kVA on the 15 kW model.
• Stored energy. Our ESA packages hold 16 to 48 kWh usable. How long that lasts depends on your load; our guide to how long a battery lasts in a blackout shows the method.
• Charge when the grid fails. A battery that has already run the evening may be close to empty at 2 am. If outage cover matters more to you than the last few kilowatt-hours of everyday saving, talk to us about how the battery’s discharge limits are set.
• Cold. The G21 battery modules charge between +2 °C and +55 °C, so a sheltered location helps solar refill the battery on a frosty morning.
• Phase. A single-phase ESA backs up a single-phase home. A three-phase home needs one of the GoodWe ESA three-phase models to keep all three phases running.

ESA packages for backup

Every ESA package includes the 63 A bypass, so whole-home backup is built into the system rather than added on. For a single-phase home, examples are the 9.99 kW single-phase system with 24 kWh and the 9.99 kW single-phase system with 32 kWh. For a three-phase home with big loads, the 15 kW three-phase system with 32 kWh lifts backup to 15 kVA. Our GoodWe ESA all-in-one guide covers the rest of the system, and our battery storage page covers home batteries more broadly.

Frequently asked questions

Does the GoodWe ESA need a gateway for whole-home backup?

No. The ESA has an internal bypass rated at 63 A, so the whole switchboard can be wired behind it without a separate backup gateway. GoodWe describes the single-phase model as offering full-house backup with no gateway needed, and the three-phase models use the same 63 A bypass design for whole-home backup.

How fast does the GoodWe ESA switch to backup power?

GoodWe rates the switchover at under 4 milliseconds on both the single-phase and the three-phase models. That is quick enough that most appliances keep running through the outage without noticing it, provided the total load stays within the backup rating of 10 kVA on the 9.999 kW models or 15 kVA on the 15 kW model.

Do solar panels keep working in a blackout with a GoodWe ESA?

Yes. GoodWe’s three-phase manual says that in off-grid mode, solar supplies the household loads first during the day and any surplus charges the battery, with the battery supplying the loads at night. If the grid and the sun are both gone and the inverter has stopped, a black-start button on the battery can restart it.

Can the GoodWe ESA run ducted air conditioning in a blackout?

It can, if the air conditioner and everything else running stay within the backup rating: 10 kVA on the 9.999 kW models and 15 kVA on the 15 kW model, with short surges above that. A large ducted system plus cooking and an EV charger can exceed it, and a big load also empties the battery faster.