Battery FAQ

Will installing a battery mean that I never receive a power bill?

No. You will still draw energy from the grid when your battery is depleted, such as late at night or when energy use is high.

Will installing a battery mean that I won't be affected by blackouts?

You will not be affected by blackouts for however long your batteries can maintain power. This varies according to what battery setup you install, and how much the battery was already depleted when the blackout occurs.

How much are batteries?

The cost of installing batteries varies greatly for each customer. A general rule of thumb is that at this point in time 1kW storage = $1000, plus installation costs. This puts the average quality residential install of around 10-15kW storage somewhere between $12000 – $16000. This is a very broad and general guide, and Jim's Energy will provide a highly specific and tailored quote for each install.

It is worth mentioning here that there are some companies currently offering battery setups at around $6000 including installation. Customers need to be aware that the size of these 1.4kW systems will only offer around half an hour of power to an average home, and are therefore not an advisable investment.

Why would I install batteries now? Wouldn't it be better to wait?

It is commonly quoted that the prices of residential batteries are likely to drop by 30% annually in the coming years. Early adopters and off-grid properties may want to make use of the great technology on offer now, but most households are likely to wait.

Does the East Gippsland Solar Bulk Buy only offer Tesla batteries?

Negotiations are currently underway between Jim's Energy and a number of battery providers. The Tesla Powerwall 2 is on offer, with a select number of options to be released on June 1st 2018. Jim's Energy is happy to discuss other options with residents and businesses to find the best deal on a quality product.

Some useful definitions:

The following definitions may be useful if you decide to do further research into battery options.

Usable Storage Capacity (kWh)

The energy stored in a solar battery that can actually be used. In most cases this is less than the nominal storage capacity.
For example, the Enphase AC battery has a total capacity of 1.2kWh. But as only 95% of that stored energy can be discharged (aka a 95% DoD) its usable capacity is really 1.1kWh.
 
Power (kW)

A battery's power is how fast it can be charged or discharged.

For example, an Enphase AC battery is a low power battery (also known as an 'energy' battery) because it takes 4 hours and 23 minutes to discharge all its usable energy, while the BMZ ESS is a high power battery because it can discharge all its usable energy in under 40 minutes.

A high power battery isn't necessarily more desirable than a low power battery - your household's unique energy usage needs will determine how much power you will require from a battery.
 
Cycle Life & Depth Of Discharge (DoD)

Besides storage capacity, this is one of the most important numbers to look at when comparing battery storage. It is expressed in a format like this: 6,000 cycles at 90% DoD (depth of discharge).

What that means is - the solar battery should be able to discharge 90% of its capacity then recharge 6,000 times before it reaches the end of its life.

Most batteries (Redflow's Zcell is a notable exception) will have a degradation in their depth-of-discharge over time. This is usually buried in the warranty documents for the batteries.
 
All In One unit

This means the system includes batteries, a battery management system, and an inverter. The Sunverge SIS is one example.
If a battery management system and/or inverter have to be purchased separately this will add to the total cost of the system.

Total warranted kWh (1 cycle per day)

If you only discharge the battery once per day (most likely for larger batteries in residential situations) then the warranty period may expire well before the warranted kWh are all used up. 

The number of kWh the battery can discharge per day is multiplied by the number of days in the warranty period to get the figures for this row.
 
Cost per warranted kWh (1 cycle per day)

This is the price of the battery divided by 'Warranted kWh (1 cycle per day)'. If you discharge the battery approximately once per day this number indicates which system may be the most cost effective.
 
A note on warranties

Some products in the table have different warranties for parts within the unit. For example, some "All in one" units warrant the batteries for 10 years but the internal inverter for only 5 years.

Further Resources

Renew Economy is a great place to read up on the latest in battery technology.

The Alternative Technology Association is a highly respected, independent non-profit organisation that provides independent advice on sustainable solutions for the home to households, government, industry and corporate clients.


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This is an East Gippsland Shire Council program powered by the Yarra Energy Foundation. Jim's Energy is the solar provider.

This program has been funded by the Victorian Labor Government under Round 2 of the New Energy Jobs Fund.