When you're purchasing a solar system, even if you're not looking at buying battery now, you're really need to think about designing the system in such a way that adding a battery later is possible. When we design systems, we ensure that the products that we use can be very easily upgraded to add a battery at a later stage. And some don't, so really what that means is that we're installing either hybrid inverters or we're installing inverters that are very easily able to have a battery retrofitted to them. We also look at putting monitoring in with systems so that we get a feel for whether or not a battery is viable for people, how big a battery you might want in the future, so we can start gathering the data so that in two to three years' time, when people perhaps have saved up some more money to purchase a battery, and the costs have come down, that we know, we all have enough information to be able to tell them exactly what battery they need and what size battery they need.

So the payback period can vary for customers, anywhere from three to four years, all the way up to sort of eight or nine years. It really depends on when you're using that power in the home. So people that are home during the day, they tend to have better paybacks than people that don't work at home during the day. That's where the case for battery sort of starts coming in. So, what that means is that you can store that solar power that you're generating during the day in a battery and then use it at night, when you're likely to be home. Ultimately, by putting a battery in, you increase the self-consumption of your solar PV. So rather than exporting it to the grid and not getting paid a lot forward, what you're doing is using that in the home later in the day or early in the morning. So that's the first benefit. The second benefit, if you are connecting that battery to a virtual power plant is that there are additional revenue streams available to the homeowner for the use of that battery. So, a retailer may say, Okay, I'm going to buy the power out of your battery because we're going to see a grid issue in the afternoon when everyone comes home and turns on their air conditioner, and I'm going to pay you for that. And certainly that amount, that revenue stream is much higher than what you would typically get from a normal feed in tariff.

They're the two major benefits of having a battery - firstly, just to summarise using the solar power in your home rather than exporting it, but also the ability to sit there and support the grid when the retailer asks for it and get some attractive returns for that.