Solar Batteries – Frequently Asked Questions Part II

Q1: Can I add a battery to an existing solar system?

YES, it is possible! The easiest way is to install an AC Coupled battery storage system, which can eliminate the need to contact existing solar wiring. Not only is it easy to set up but it is also a more economical way to increase energy storage. For example, Tesla Powerwall 2, Alpha ESS, or Huawei.

Q2: Can I use a single-phase battery with a three-phase existing solar system?

YES, you can. Physically, the battery is connected to one of the three phases, but the battery will measure the total solar export to maximise self-consumption by charging with excessive solar. The electricity meter (for billing purpose) will automatically calculate the total net power (in/out) on all three phases. In other words, it is equivalent to a single phase battery that can be charged with three phases of solar system.

Assuming that the total power generated by the three-phase solar is 6kW and the single-phase battery is charging 5kW (for your electricity usage at night), the utility meter will automatically calculate the net export as 1kW (you can sell the electricity back to the grid). 

Q3: Can the solar system still charge the battery in the event of an outage?

Definitely! The first scenario is a DC Coupling solar + storage battery system. The second scenario is that some of the AC Coupled battery systems also offer this function, for example: Tesla Powerwall 2.

Q4: How do I choose a battery storage system?

Firstly, you need to take into account your electricity usage and load power at night. Secondly, you need to know the size of your solar system and ensure that the existing solar system can fully charge the battery during the daytime. Thirdly, you need to know whether you want to add a backup function to your battery and whether you will need the solar system to work during the backup period. With the backup function, you will be able to power your home appliances in case of a power outage, without panic.