What you need to know about
Battery enquiries have been skyrocketing over the last year with more and more enquiries and questions regarding whether batteries are they worthwhile.
If you’re installing batteries for the right reasons and you want to take advantage of excess power that would have otherwise been sent to the grid bu using this at night for your own purposes, then solar batteries may be a good option. An added bonus of many solar batteries is blackout protection when the grid goes down.
If you’re only installing batteries for the financial benefits then we would highly recommend doing the calculations or speaking to a designer first. It is important to get accurate information on your specific scenario. We still find that without rebates the payback period is approximately double the time of a standard solar panel system.
It is a complicated area and with new technology coming onto the market each day it is something to keep in mind and clarify with a designer and installer before moving forward with a purchase.
There are state government incentives that may be available to assist in financing a battery solution. Check out our page dedicated to Rebates for further information.
Batteries capture any unused solar power that is generated during the day. Batteries then give you the capacity to draw off this saved power at any time when your consumption is larger then the amount of solar PV being produced at that given time. One of the major benefits of batteries outside of the financial benefits is the ability to produce power in a blackout without the grid. If your solar system is large enough a battery could make your house self sufficient for a large portion of the year.
If you do not install a battery there is no option to have blackout protection on your solar system. The standard solar system requires the grid and synchronises to the grid to allow the solar production. The new battery systems create an artificial grid that works in conjunction with your appliances and household loads to allow functionality in blackouts whilst also protecting the actual grid by locking out the ability to export any power.
Depth of discharge (DoD)
Batteries are designed to work within parameters to not be harmful or detrimentally impact on the life of the battery. Lithium batteries (which is what most hybrid solutions are in the market) can safely be discharged up to 80 and 95% of their nominal capacity. This would mean a 10 kwh nominal battery would have a usable capacity of 8 to 9.5 kwh.
The unit of measurement for batteries is kilowatt hours (kwh) and the definition nominal capacity is the amount of power the battery can hold. This however is different to usable capacity which is the amount of power the battery can deliver due to the depth of discharge allocated through specifications.
When battery manufacturers talk about warranties, they usually write these in cycles. The cycle life of a battery is how many times you can charge and discharge the battery before it is considered to reach the end of its life. As a guide lithium batteries can have life spans / cycles of between 2000 and 10000. You should also expect that over the lifespan of the battery the efficiencies of the battery will also become depleted. A 10 kwh battery out of the box in 10 years time may only have a usable capacity of between 5 and 8 years as an example. Batteries cannot hold their full capacity indefinitely.
There are lots of variations of lithium batteries from lithium nickel manganese cobalt (NMC) used by Tesla and LG chem. As well as lithium iron phosphate (LiFePO) used by companies like BYD and Sonnen. These are very similar in manufacturing process with similar pros and cons.
Other options with batteries may include flow batteries where electrolytes are pumped around and chemical reactions are used to charge and release. Such batteries include Redflow. There are also saltwater batteries and recently announced supercapacitors. These are not common but with technology advancements these options and many others may become viable options moving forward.
Batteries do have some limitations as to the amount of power that can be used and harvested at any given time. There are specific charging rates 4 batteries and this is determined by the specifications of the battery and the charging unit / inverter hooked up in conjunction with the battery. As a guide, at the moment the majority of battery systems can allow up to 5 kilowatts or 20 amps of power to be sent to and from the battery at any given time.
So should I install a home battery?
With the return of investment for solar panels at a very viable level, and the return of investment for solar batteries still sitting a lot higher, the question is: should I install one?
We personally believe that without financial incentives from the government at the moment it does not make complete sense to install purely for financial reasons. You may even find that the payback is longer than the warranty and expected lifetime of the battery. Lithium ion battery systems installed in conjunction with a management system and hybrid inverter can cost anywhere between $6000 and $16,000 depending on the size and the manufacturer.
Pricing has fallen quite a lot over the last two to three years, this has slowed down recently but is expected to continue will continue into the foreseeable future. We look at your specific scenario in deciding whether it makes more financial sense to install a hybrid inverter now or not.
Having a battery that offers blackout protection (especially in rural areas where power is required for pumps and fire protection) battery solutions can be a great option today.
So when making the final decision on whether a battery solution or a solar system with a hybrid inverter is the right option for your home, we highly recommend you speak to a specialist. It is vital to get a more detailed understanding on how solar batteries function, what options are available and whether a battery will actually serve your purpose. A battery will not always be the right option for every client.