Solar Power + Battery Grid Connect

A grid-connected solar system with battery storage generates power in the same way as a typical grid connected solar system, but has the ability to store surplus energy generated for later use, rather than exporting it all to the grid.

In light of increasing power costs, limitation of solar inverter to one tariff, and with the end of the Legacy Tariff, many consumers are beginning to consider the advantages of adding battery storage to their solar array.

Conceptually, the addition of batteries is a highly attractive option. Benefits include:

  • Optimised use of power generated by own PV system
  • Ability to use own power during Peak periods, even at times of low light or inclement weather
  • Reduced reliance on grid-sourced power
  • Lower power bills
  • Greater power security
  • Greater autonomy
  • Minimisation of power consumption from less ‘clean’ sources

This option is becoming increasingly more accessible and affordable. To help provide general information regarding this topical issue, we have addressed some common questions below:


Can I add batteries to my existing system?

Yes. There are now a significant number of user-friendly batteries available on the market that can be added to nearly any existing solar systems, including (but not limited to) sonnenBatterie, Tesla Powerwall V2, LG Chem, and Enphase AC batteries.


Is it worth installing batteries?


As mentioned previously, there are a multitude of benefits associated with the installation of batteries. Battery systems installed by MODE have the additional benefit of providing a visual interface for monitoring energy consumption, enabling you to take steps to manage your own energy in a way best suited to your individual needs. You are able to keep your own energy, to use in your own time, without being compelled to export and re-purchase your own power from the grid.

In addition to the practical and financial advantages of battery installation, there are also more complex rewards associated with the responsible stewardship of our resources – the satisfaction of greater autonomy from utilities, a greater degree of security in power supply, and the knowledge that each of us are able to take steps to help care for our wondrous planet.


When should I install a battery?

This depends on your individual circumstances.

Although the installation of a battery still requires a significant financial investment, prices have dropped significantly, and home batteries are becoming a far more cost-effective power storage solution. Feel free to contact us if you’d like to discuss whether now might be a good time for your to invest in battery storage.

Please note it seems reasonable to expect battery prices to continue to fall over time, as technology advances, competition increases, and as more and more people take up this new technology.


If I install a battery, will I have power when the grid goes down?

It depends on your type of solar/battery storage system. There are a number of system options available in relation to batteries:

Grid-Connected with Battery Storage

Grid-connected batteries are most commonly lithium ion batteries, such as Tesla Powerwall, Sonnen Eco, and Enphase AC. They are able to store surplus power from your solar array, and to supplement your power needs overnight or during periods of inclement weather. Although many people expect these batteries to automatically enable them to keep power when the grid goes down, this is not the case;  when the grid goes down, your battery-connected hybrid system will automatically shut off. This happens for two main reasons:

  1. Both the battery interface and your solar inverter are actually powered by the grid. When the grid goes down, they will shut off just like your other electrical appliances.
  2. It is important that your solar/battery power systems are electrically isolated and don’t back-feed into the grid when the grid goes down. This is necessary to prevent the accidental electrocution of technicians working on restoring the grid.


Grid-Connected Hybrid with Back-up Function

Most of the better grid-connected batteries on the market have a back-up function available. The nature and capacity of this function varies from battery to battery. Some may have a simple function that requires you to manually switch over to back-up for a specific pre-selected power circuit (lights and fridge, for example) when the grid goes down, and will then pull power from the battery until it is flat. Once the battery is flat, you will have to wait until grid power is restored before you can use any further power. On the other end of the spectrum, there are back-up functions designed to automatically isolate your system from the grid in event of grid failure, and then allow you to draw from both your solar array (during daylight) and battery to power specific pre-selected circuits during a power outage. Back-up functions start around $950 and go from there.

Grid-Connected Battery with UPS design (Hybrid System)

One step further along, but requiring significantly more complex design (with associated cost), is an option of having a grid-connected system with Uninterrupted Power Supply (UPS) built into the system, so that you can be on the grid, but have the ability to retain full power if and when the grid went down. This is generally referred to as a ‘hybrid’ system.

It is possible to have a true back-up hybrid system, where your battery will continue to provide power to your home when the grid goes down, but this involves more complex system design. Unless you have critical loads that require a 24/7 power supply, or you live in areas where there are frequent power outages, it is generally better to simply invest in a regular hybrid system (with back-up, if desired).

 Off-Grid system

A true off-grid system would mean that you are completely removed from the grid. This is a lovely thought, but involves careful planning and the willingness to commit to a particular way of life. If you’re interested in what this involves you might like to check out these links:

Can I go off grid? Is it worth it?

Once again, this depends on individual circumstances and life-style.

Although living off-grid is ideologically alluring, and comes with very real benefits, there is much more to going off-grid than simply investing some dollars for an idyllic sea-change.

It is a serious commitment to a particular way of life.

If you are currently grid-connected, it would generally be best to remain so, unless your house and life-style lend themselves to off-grid living, and you choose to go off-grid as a matter of principle, rather than as a cost-saving measure.

Consideration needs to be given to non-electric power sources for cooking, heating, and hot water. The short video below will help you think through what going off the grid looks like.

For anyone building a new home where it will cost $15,000 or more for power connection, however, it may be worth seriously considering going off-grid, and to design your house accordingly. See our case study of a house designed for optimum energy consumption for an example of what can be achieved when architecture and technology are synergistically designed to optimise efficiency and performance.