Frequently asked questions

Why is RESU so much less expensive than other alternatives? Is it inferior?

Not at all! LG Chem RESU is cheaper because we actually manufacture our own battery cells. We even supply cells to some of our competitors! As the cost and technology leader in both residential and automotive battery markets, with approximately 130,000 homes using RESU and 1 million electric cars using our batteries, with grid scale and commercial storage, we have large manufacturing volumes allowing us to achieve low cost combined with maximum quality.

Does RESU require an additional inverter?

Yes and no. Confusing? Let’s explain. All batteries are DC (direct current).Solar power is also DC (direct current). Household power is AC (alternating current). So whenever solar or battery power is used to power AC loads, an inverter is required to change the DC to AC.
This can be a PV (solar) inverter, a battery inverter (technically a inverter-charger) or a hybrid inverter which, as the name suggests, is a combination of the two.
All batteries require at least one inverter, and RESU is no exception.

What then is an AC battery?

Some products are sold as “AC batteries” and these are actually a battery and inverter integrated into a common enclosure. Examples are products from integrators like Eguana, Sonnen, Tesla and Varta.
Note that AC batteries always require a separate PV inverter.

So, what do I need?

There are 4 main scenarios, depending on your current situation.

  • (a) I have solar with a PV inverter and I don’t want more solar:
    RESU plus battery inverter.
  • (b) I don’t have solar at all :
    RESU plus hybrid inverter
  • (c) I have solar with PV inverter and I want to expand my solar system :
    RESU plus hybrid inverter.
  • (d) I have solar with RESU-compatible hybrid inverter RESU only

If it’s all a bit confusing, don’t worry! Simply ask your quote provider for advice.

How does RESU know when to charge and discharge?

This is handled by the smart controller in the inverter the RESU is connected to. A meter in the switchboard measures whether the system is exporting to the grid or importing. Generally you want to use your excess solar power to charge the battery rather than export to the grid, and generally you want to use solar power stored in your battery to power your home rather than buy electricity. That’s your “plain vanilla” home battery system. But some inverters have other functions too, such as time-based charging, energy trading and smart home control of discretionary loads. In most cases it will be future offers from retailers that will make those extra functions worthwhile.
See also FAQ below about back-up.

What size RESU should I get?

Any size will help reduce your power bill, but the optimum size is usually one that has the capacity to store your excess solar production plus leave an amount for emergency back-up in case of a power outage.

So does RESU give me back-up power?

RESU can deliver strong back-up power in the case of an outage. But it is also important to select the right inverter to match your back-up needs. Most hybrid inverters and many battery inverters provide back-up power. Please consult with your quote provider.

In case of an outage, my solar stops working though, right?

You’d think so, because that is what happens with a PV inverter, whether there is a battery in the system or not. But with RESU, not necessarily. Some hybrid inverters from SolarEdge, Goodwe and Sungrow actually allow the connected solar to keep working. If it is a sunny day, your battery might even be charging as well as supplying your backed up loads! Not all hybrids have that feature though, so again, please check with your quote provider.

Can RESU operate completely off-grid?

Yes, provided you are using the right battery inverter, such as SMA Sunny Island or Selectronic SP-PRO. Hybrid inverters are not intended for off-grid use.

I have 3-phase power, what are my options?

You can either

  • (a) Use a Fronius Symo 3-phase hybrid inverter plus RESU That will give you self-consumption across all phases but no back-up
  • (b) Use a 3-phase PV inverter and connect a battery or hybrid inverter plus RESU to one or more phase. That will back-up the connected phase only (assuming the inverter has back-up) and still give you self-consumption across all 3 phases.

Another one to discuss with your quote provider. See how RESU is so flexible?

Can I expand my RESU system later?

We do have expansion options. With Solar Edge there is an optional RESU10 secondary battery. With SMA Sunny Boy Storage 5.0 you can connect up to 3 batteries. With most other inverters, a RESU Plus allows the connection of a second battery later. A word of caution though – technology is constantly advancing, we will keep developing new solutions and we can’t guarantee backwards compatibility into the future.

How do I know if my battery is working properly?

RESU sends information constantly to the inverter, and the inverter reports that information on its monitoring portal and/or phone app. In addition, you can set up text or email alerts, depending on the inverter

Where can RESU be installed?

Indoors or outdoors.
Indoor installations must comply Australian regulations and commonly a garage or utility room is used.
Outdoor installations should be in a shaded area such as a carport or south-facing wall under an eave.

Where do I find a quote provider?

Please see website for “find an installer”