Are Solar Battery Systems Worth The Money?


Battery storage systems have been available within Australia for a number of years. These systems have been highly priced, the equipment is large and bulky, and a great deal of knowledge to operate and maintain these systems is needed. However, there is a new generation of energy storage emerging within Australian. These storage systems are more cost effective and better looking than previous systems. They will become a common addition to solar and smart households around Australia.

How Battery Storage Systems Work:

  1. Solar panels convert sunlight to DC electricity.
  2. If there is a surplus of DC electricity, it charges the battery storage system.
  3. Your solar inverter converts DC electricity to AC, which is able to be used within the home.
  4. Some solar inverters can convert AC to DC electricity to charge your storage systems using cheap off-peak mains power.

Battery Efficiency

This refers to how much energy is successfully stored and converted to electricity for household use. Obviously, battery systems cannot have perfect efficiency, but some models and systems come very close. You want to purchase the highest battery efficiency system.

Solar battery life, or the period of storage, is measured in cycles. Assuming there is one cycle per day, meaning the process of filling and emptying a battery, you want to purchase the system with the most durable cycles.

Feed-In Tarrif

This type of tariff is basically a rebate on your energy bill. For every kilowatt your households solar system produces but does not use, it is fed back into the grid. So if you get paid for energy generated but not used, why store the energy? Across Australia, there are high tariff rates, such as the NT, and low tariff rates in areas QLD, Tasmania and Victoria. So if you live in an area with high tariff rates, you can benefit from “selling” your energy back to the grid.

The Tesla Powerwall 2

Fact Sheet:
Storage = 13.5kWh
Power = 5kW steady, 7kW peak. It can power an average 2 bedroom home for an entire day
Battery Efficiency = 92.5%
Cost = $8,000 plus GST and installation
Features = compact, stackable, indoor or outdoor and installation is relatively easy


System Layout:


In What States to Install a Powerwall 2:

If you are purchasing and installing a Powerwall 2 for money saving and economic reasons, then the states of Western Australia, NSW and South Australia are the best installation locations. Mainly because of the high peak electricity rate and time-of-use tariffs.

Who Benefits From a Powerwall 2?

The Tesla Powerwall 2 is going to be big. So big in fact that its large capacity is more than the average household requires at night. If you have a Powerwall 2 installed, you are basically using it at less than its full capacity. Meaning you are not really getting your monies worth.

Although the Powerwall 2 is bigger than the average battery storage system, households with large families or ones that don’t have gas will benefit greatly from this system. If you have the energy stored, you might as well use it rather than waste it.

If you’re unsure about whether or not to install a Powerwall 2, the best place to start is to determine how much electricity your household uses.

  1. Inspect your electricity bill. If you use, on average, less than 13.5 kilowatt-hours of grid electricity per day, you’re not going to reep the benefits of a Powerwall 2 at high capacity.
  2. Install an energy-monitoring device. This device will tell you exactly how much and on what appliances you are using your electricity.
  3. Smart Meter. If you have a smart meter, you can request a breakdown of your electricity consumption from your electricity retailer.

Average Electricity Consumption in Sydney:

Lets say that a household in Sydney has 4 residents and no gas. This means that:

  1. The household uses on average 20.1 kilowatt-hours per day
  2. Lowest daily consumption is in Summer (18.2 kilowatt-hours per day)
  3. Highest daily consumption is in Winter (24.8 kilowatt-hours per day)

Charging With Off-Peak Power:

The Powerwall 2 can be charged with off-peak power if the solar output is not efficient. Unless you have a high solar feed-in tariff, if you charge with off-peak electricity this will always be more expensive. If you do have a high feed-in tariff, then battery storage definitely is not the solution for you.

The Verdict: Are Solar Battery Systems Worth The Money?

We recommend to not install a Powerwall 2 unless your household averages around 12 or more kilowatt-hours of electricity OVER NIGHT. We also recommend not installing a Powerwall 2 unless your solar system produces surplus electricity to fully charge it on a clear sunny day. This usually requires at least 5 kilowatts of solar panels.

A battery storage unit will help you reduce your grid energy demands and requirements, but you won’t necessarily save money given that storage units are very expensive. If you are smart with you energy usage, ineligible for feed-in tariffs or have high electricity rates, then battery storage systems are worth the investment.


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