Following on from last week’s FAQ, ‘Should I install solar panels on my home’, Ty Christopher, Director of the Energy Futures Network at the University of Wollongong, answers two common questions about batteries.

So I’ve got solar panels, should I get a battery for my home? 

The answer to that is look very carefully at the cost versus the benefits. Because in most cases, when you look at the significant cost of the installing of a battery and the benefits that it'll yield by storing only some of the solar that you'll generate during the day and allowing you to use it once the sun's gone down, over the practical life of a battery – which is determined by the number of times you charge it and recharge it, but in rough numbers, 10 to 12 years for a home battery – in many cases, the economics are barely positive and in many cases they're not. 

My first question for someone who asks me ‘Should I get a battery for my home?’ is, ‘How are you heating your water?’ 

Because in a temperate climate such as the Illawarra, depending on your home, around one-third of your energy goes into your water, heating it from whatever source you are using. 

So before a person considers a chemical battery, a lithium-ion one, the better thing to do is to look very carefully at considering what I call a thermal battery, which is your hot-water system. 

With the government rebates being very attractive at the moment, look at getting a highly efficient heat-pump electric hot water system, and run it during the day when the sun's shining and store the solar in the form of hot water. 

That, at the moment, is a far more ecologically and economically good thing to do as a household than to look at buying a household battery. 

That may change. Battery prices may come down and that will shift the balance. 

I'm not saying, therefore, I'm anti battery or anything like that. Full disclosure, I work with an Australian company which manufactures community battery technology here in Australia. I do strongly recommend people look at the costs and benefits of a home battery before jumping in. That's the fact as it stands at the moment – for most homes, before you even consider a battery, look at what you're doing for your hot water. 

In the energy transition, which is better – household or community batteries? 

The answer is ideally a mix of both. 

It's counterproductive in the energy transformation debate at the moment to be constantly setting an ‘or’ mindset around technology pathways. When you boil it down, there are sensible and practical roles for nearly all of the technology to play – in the right space. 

It's not a silver bullet solution; it’s a silver buckshot solution. 

And so, on home batteries versus shared batteries the answer is probably a good, well-executed combination of both. 

ARENA, the Australian Renewable Energy Agency, did a study a few years ago, it was called Grid versus Garage, where they explored the economics and the practicalities of grid side of the meter, shared storage on the low-voltage network – basically, to time shift and soak up solar output – versus individual garages or basically individual home batteries. That report really went thoroughly through an analysis of all this and clearly concluded that grid side of the meter storage is the best, most economic solution. 

It's challenged by the regulatory structures, but one of the great benefits of grid side of the meter shared storage is it democratises access to locally generated clean energy.

And it starts to open up the potential for people who don't have access to a roof – renters, lower socioeconomic areas, et cetera – to access cheaply generated, locally generated clean solar energy. 

For me, that's what tips the scale over, while a future of energy storage should have a mix, I think that there is more benefit for us in terms of equity of energy across our society, as well as overall reduction of carbon footprint to have more of a dominance of coordinated grid side of the meter storage, because it really does open up access to clean energy at the local level. 

Ty Christopher, Endeavour Energy’s former ‘chief engineer’, is an electrical engineer who brings 37 years of hands-on experience in the power supply industry to his current role as Director of the Energy Futures Network at the University of Wollongong.

Read more Energy Explained articles

• Should you put rooftop solar on your home?
• The case for home and community batteries
• Electricity Regulation – Kicking goals or killing time before the bell?
• The hidden cost in your electricity bill
• Why restructuring the market may save you money
• Why should we 'Electrify Everything' – and why can't Wollongong run on sun?
• How much power can solar actually deliver?