People are forever asking us about battery storage and energy independence. Battery storage is an essential step to achieving complete energy independence at home and will revolutionise the future of energy usage. Battery storage will empower us to do many things, such as:

  • Store solar energy produced during the day and use it at night
  • Provide your home with backup power in case of a grid outage
  • Manage time of use tariffs (TOU) to buy energy at cheap off-peak rates
  • Enjoy a premium rate for the surplus energy you sell back to the grid

While it is possible for many homeowners to completely disconnect from the grid, we advise against doing so. If you were to be completely off-grid, you would not only require additional components which can prove rather expensive, but you’d also find yourself without backup power if one of the components fails. The existing grid is actually a very cost-effective means of meeting your household’s peak power demands, plus you may also be able to take advantage of the premium rates that retailers frequently offer if you’re able to sell power back to the grid at peak times (see the off-grid or backup power systems section below for further information).

Battery Storage – The Financial Benefits

At the present point in time, home battery systems are still not as cost-effective an investment as solar power, solar hot water and other available technologies. Therefore, it’s unlikely that you will be able to recuperate the financial outlay involved in a practical timeframe or before the warranty period expires.

A battery storage system capable of storing 6 kWh of excess solar production over the course of the day only delivers savings of around $400 annually. And that’s provided every battery is used to capacity on a daily basis, which is quite unlikely, plus there’s the reduction in storage capacity to take into account which occurs quicker in batteries than it does in solar panels.

What’s more, it’s also a sizeable investment – it adds $8000-$10,000 to the cost of a new solar power system or $9000-$11,000 to retrofit into your home. Given the minimal savings, the reduction in storage capacity and the sizeable outlay involved, a home battery system simply isn’t a savvy investment, at least not at the moment, though having said that, prices are dropping rapidly.

Some home battery systems enable you to sell stored energy to the grid during peak times, which could see you enjoying premium rates. However, you need to produce more energy than you consume in order to do this, which may mean you need to power down your home appliances.

Retrofitting a Home Battery System

Although it involves a significant financial outlay, retrofitting a home battery system is quite straightforward and requires the addition of just several components to your existing system – the battery, a battery inverter and a metering unit. The best time to store power is when your system is producing excess, provided that you’re not selling power back to the grid at peak times or manipulating TOU tariffs, and the best time to use this power is when your system is unable to keep up with demand.

As batteries store power in DC, not AC, be aware that this particular retrofit doesn’t allow your system to do backup power (see the off-grid or backup power systems section for further information). This also means the battery inverter needs to convert DC power from the batteries into AC power to be used for the home in addition to converting AC power from the solar panels (or the grid) into DC power for the batteries to store. In comparison, a solar inverter only needs to convert the DC power from the batteries into AC power to be used by the home.

Our range of battery inverters includes the Fronius Smart Meter, Enphase Envoy-S Metered and SMA Energy Meter, each of which is compatible with its own metering unit mounted in or near the switchboard. This device plays a very important role, that of telling the battery when the system is producing excess or not keeping up with demand so that it knows when to store power and when to use the power stored in the batteries.

Battery Ready and Backup Ready Vs Battery Compatible – Which is Better?

Our interpretation of a battery ready system (please note that other sources may have different interpretations) is a system with the inverter and metering unit already installed and is ready for use as soon as the batteries are added. An example of this is when you have a battery inverter or hybrid inverter that enables you to connect the batteries directly to the other two components.

Battery compatible systems are existing systems in which a battery with a battery inverter and all the required components can be retrofitted (see the retrofitting a home battery system section above).  All currently installed solar power systems fall into this category, with most systems unable to be configured in order to provide the home with backup power.

A backup ready system, on the other hand, is any system that can be configured to provide backup power with an Automatic Transfer Switch (ATS). These systems may or may not use batteries, and not all battery and hybrid inverters offer this functionality, so be sure to check when purchasing a backup ready system.

An example of a backup power ready inverter is the Fronius Symo Hybrid, which requires only the ATS and a firmware update. However, as many other battery and hybrid inverters lack this capability, they would need to be replaced (see the backup power and systems section below).

Backup Power and Systems

As discussed above, although a system may have batteries, that doesn’t mean it automatically provides backup power since not all battery and hybrid inverters are capable of delivering backup power, plus additional components are also required.

Additionally, there are a number of issues that need to be considered here, such as how to prevent excess power returning to the grid. In new backup systems, the Automatic Transfer Switch (ATS) switches off when there’s an outage in the grid and then switches back on again when the power returns. Once switched off, it tells the backup capable inverter that it’s safe to generate power once again.

In existing solar power systems, when power is being produced by the backup system the existing inverter mistakes solar power for grid power and also begins creating power. This results in too much or too little power being made available which the backup inverter is unable to control, ultimately resulting in everything shutting down.

Inverters which can be controlled by the backup inverter can prevent this from happening, as can opting for a hybrid inverter which stops this from occurring as everything is in the one device. If you want backup power, you’ll most likely need to replace your existing solar inverter.

Something else to note about backup systems, is that when they’re providing backup power and cannot meet demand they will shut off. This makes it important to segregate essential from non-essential loads in case a grid outage occurs, so that essential loads, like lights and refrigerators, are covered while non-essential loads, like air-conditioning units and washing machines, switch off automatically.

To achieve this, essential loads need to be put on separate circuits, but note that the more essential loads you add the greater the power you’ll need available, which means you’re less likely to meet demand and are, therefore, at greater risk of losing all power.

Off-Grid or Backup Power Systems?

Off-grid systems and backup power systems are very different in a number of ways. Whereas an off-grid system is designed to work without access to the grid, a backup power system makes a portion of power available for use when there’s no grid power available. To achieve independence from the grid, an off-grid system not only requires additional components which can be quite expensive because they must be high-capacity, as the system must also be capable of covering high energy demand situations, for example, providing the home with power on an overcast day.

What’s more, there’s a great degree of risk involved with off-grid systems because should a single component fail, the entire system would shut down and leave the home without any power at all. This in turn increases the need for alternative backup power systems, such as diesel generators, which further adds to the costs involved. Subsequently, this is why we advise not going off-grid unless you lack access to a reasonably reliable grid connection.

Considering a Home Battery System? Here’s Our Advice

Solar Repairshas an excellent variety of storage products available and there are many more products on the way. Due to our industry connections and experience we have direct access to numerous battery storage manufacturers and we’ve evaluated the products they supply in order to select the very best to make available for our customers. We have already installed a variety of systems, including residential grid connect battery systems and hybrid inverters, and as we’ve worked on many off-grid products, we’re certainly no newcomers to battery storage.

Battery technology has arrived and is set to revolutionise the way we view household power, so if you’re eager to be one of the first to incorporate this technology into your home we’re in the perfect position to help you achieve this. However, as we stressed earlier, if your motivation for installing a home battery system is strictly financial, now really isn’t the time due to the major financial outlay currently involved. That, however, doesn’t mean you can’t start planning, which is highly advantageous due to the nature of incorporating such new technology.

Here at Solar Repairs, we believe that the best way to start planning for the future is to invest in a power consumption measurement device so that you can start calculating how much energy you need to store at home. Some inverters, like those in our Fronius and Enphase range, enable you to add such a device, which we recommend you install with your new solar power system. If you have an existing system we can retrofit a device that will provide you with energy consumption data, like the Enphase Envoy-S Metered, which is an excellent choice as it records this data which can then be viewed on their portal or app suite.

The additional consumption data generated over the course of a year or two will empower you to fully understand your energy storage requirements and make the right decision on the size of the batteries your system requires. This is an important decision to make, for should you choose the wrong sized batteries it could prove to be a very expensive mistake, depending on the technology incorporated. Please contact us if you have any queries concerning batteries and battery storage.