Retrofitting batteries for your home solar power system

Submitted by Webmaster on Tue, 04/10/2016 - 15:21
retrofitting battery


You’ve already invested in a solar PV system for your home (or are thinking about doing so) and, now, you’re wondering how you can maximise your savings by adding battery storage into the mix. Read on to discover just how easy it is to retrofit batteries to your solar power system.



Battery storage is the way of the future

According to the Climate Council, Australia is expected to be one of the largest markets for battery storage due to:

  • the high cost of electricity
  • the large number of households with solar panels
  • Australia’s excellent solar resources

As feed-in tariffs are phased out (meaning households receive less money for the solar electricity they put into the grid) and as electricity prices remain high, the Climate Council anticipates that solar PV systems with added battery storage will become the most economical solution to provide electricity.

As the price of battery storage falls and grid electricity remains expensive, they predict that, by 2018, going completely ‘off-grid’ (and relying solely on battery storage) could be cost-competitive with sourcing your electricity from the grid.

(Climate Council of Australia, 2015)


The benefits of battery storage

Regardless of whether you go completely ‘off grid’ or not, battery storage systems can almost double a household’s self-consumption of solar PV. For example, adding a 4kWh battery to a 5kWh solar system can increase the amount of self-generated solar electricity a household consumes from 30 to 60% (IRENA, 2015).

In short, a home battery system enables you to extract and store electricity from the grid at off-peak times (when it is cheapest) and use the power stored in your battery at peak times (when electricity from the grid is most expensive), significantly reducing your electricity costs.


How do I add battery storage to my existing solar power system?

With most existing solar power systems, the best way to retrofit a battery system is with a battery inverter, a metering device and a suitable battery.

  1. The battery inverter talks to the battery and converts AC power from the house into DC power for the battery and vice versa.
  2. The metering device tells the battery inverter when power is going back to the grid and, hence, when to store power.
  3. For help choosing the right battery for your home, visit the battery section of our website.


There are a couple of ways Solargain can retrofit your battery system

Your first option is the new SMA Sunny Storage 2.5 with the SMA Energy Meter. This battery inverter has been designed for and is only compatible with the Tesla Powerwall. Solargain is one of the few authorised distributors of the Powerwall. The SMA and Tesla Powerwall option comes with the SMA Energy Meter and we can install that with the Tesla Powerwall for approximately $11,490.

The second and more prominent option is the new Enphase AC Battery. The Enphase AC Battery is a small battery with a built-in inverter. We prefer this solution as it’s modular and uses the latest LiFePO4 chemistry. LiFePO4 chemistry is safer, longer lasting and allows more cycles, all of which are very important for residential storage. It’s also much easier to scale up your storage if you need to and you can do two full cycles per day with the battery instead of one – essentially doubling the effectiveness. Visit the Enphase website for more information.

The Enphase AC Battery will be available for installation through Solargain in October. Please note that this system requires an Enphase Envoy-S Metered monitoring device installed at the home. Solargain will handle your network application; however, time frames and approval are subject to your network operator.

The price of this additional component is noted below.*

Indicative pricing using the Enphase storage system
# Batteries installed Usable capacity Approximate price
1 1.1kWh $2,900
3 3.4kWh $7,490
6 6.8kWh $13,990
9 10.2kWh $20,990

*Enphase Envoy-S Metered costs an additional $500 (with a battery install) or an additional $790
(if installed on its own).


When considering an Enphase system, we recommend you install the Enphase Envoy-S Metered first. In doing so, you’ll start to accumulate all the consumption data required to make an informed decision about which size of battery you need and how much it can save you. With the Enphase Envoy-S Metered you will also be able to see how your existing system is currently performing via the Enphase portal. This video shows the kind of data you can collect.



How can I ensure my system is ‘battery ready’?

Many solar companies promote the importance of having a system that is ‘battery ready’. However, at Solargain, we don’t get hung up on this concept, as adding battery storage to homes with (or even without) solar power systems is really very easy. The hard part about adding battery storage is choosing the right size and type of storage you need.

As mentioned earlier, the best way to determine what system you need is to install a device that monitors and records your consumption data, so you have a history of consumption to base your battery decision on when the time is right. Whether you choose the Enphase monitoring system that we touched on previously or a Fronius system (see Fronius data here), you’ll be well informed when it comes time to choose a battery.

So when it comes to being ‘battery ready’, we simply recommend you install:

  • a device that records the consumption data in the home and
  • a solar power system that produces enough energy to power your home all day. (You don’t have to install all the solar panels now, but if you plan to go battery down the track, you’re going to need a big enough solar power system to cover your load during the day and have enough spare power to charge the batteries.)


Should I choose a hybrid inverter?

Hybrid inverters are inverters that connect to solar panels and batteries at the same time. While they seem like a good idea now, there are a few things to consider before investing in this kind of system:

  • They’re much more expensive than standard inverters; in most cases, at least $2,000 more.
  • They’re very new, untested and lack basic functions. For example, most don’t even let you do backup power yet, which most people consider to be a standard feature of battery systems.
  • They may not be compatible with the battery you want. For example, the Fronius Symo Hybrid inverter is not available with the LG Chem battery or the Redflow ZCell battery. The Sungrow Hybrid isn’t available with the Tesla Powerwall battery. If you choose a hybrid inverter now, there’s a good chance it won’t work with the battery you want down the track.

With these points in mind, be wary of solar companies pushing you towards a hybrid inverter. Solargain would only recommend you chose a hybrid inverter if you were purchasing your batteries at the same time as the installation. Otherwise, we recommend you wait and purchase a battery inverter once you’ve chosen the right batteries for your needs.


Do you still have battery-related questions you’d like us to answer?

Upgrading your solar PV system to include battery storage isn’t a process you need to wade through alone. You can rely on our team of solar power and battery technology experts to answer your questions and help you choose the best system for your household.

If you would like more information about retrofitting a battery to your solar power system, please give us a call on 1300 73 93 55 or contact us online today.