A bit of History
Back in 1800, Alessandro Volta (from whom we get the term ‘volt’) invented the first true battery after experimenting with copper and zinc and brine soaked cloth or cardboard, or really anything lying around his lab at the time. His battery produced charge but was spent after an hour. Further complications arose around corrosion, hydrogen bubbles and the like.
From the 1830’s through to the 1850’s, there was a flurry of battery development activity from all over the place, including contributions and developments from various geniuses from France, England, Scotland, Wales, but it wasn’t until 1859 that a French bloke named Gaston Plante came up with the first rechargeable battery – the lead acid battery. Remarkably, lead acid batteries are still in use today, some 160 years later.
Boffins continued to experiment with various combinations of primary elements to refine the battery’s performance throughout the 20th century including nickel-hydrogen, nickel-metal hydrate but it wasn’t until 1985 that Akira Yoshino of Asahi Chemical Co, Japan invented and patented the first Lithium-Ion rechargeable battery. Which brings us to the subject of our Battery School.
What is battery storage and how does it work?
What we are talking about is solar or PV storage systems for use in powering your home. The simple premise is your PV or solar panels produce free electricity, you use some of it and the rest flows into your battery to be drawn upon at night once the sun has set and your PV shuts down. So you still have free power to use at night.
Say, for example your house consumes around 20kW of electricity per day. 50% during the day, 50% at night. Your PV produces 20kW per day BUT only when the sun is shining. A perfect situation is one where your PV accounts for your daytime usage (10kW) and sends the excess power generated (10kW) to your battery to be used at night. Voila! 100% self-generated and consumed electricity, a perfect circle. It’s a bit like using your mobile while it remains plugged into its charger – you are using your phone but will be able to keep using it once you pull it out of the USB port.
Are all batteries the same?
Noooooooo. No, no, certainly not.
Chemistry: Almost all residential batteries use a chemistry called Lithium-Ion. What people don’t realise is the term “Ion” is a generic term for several different chemistries that all work with Lithium. Lithium-Iron-Phosphate is a non-combustible, low risk, benign combination that lasts longer, has lower degradation percentages and is safer. The downside is they are slower to charge and discharge. Lithium-Nickel-Manganese-Cobalt is a much faster charge/discharge chemistry that is also used in almost all electric vehicles. This is because it is lighter and makes the car go quicker. Same with home storage. The downsides are the degradation is much higher, shortening its lifespan. And NMC is highly combustible – like really high. Google something called “thermal runaway” for an eye opener.
Size: Batteries come in all shapes and sizes, both physically and in their storage capacities. Some are tiny but modular, insofar as you can add more as needed, some are simply one size – but that doesn’t fit all, as I will explain. Batteries are sized in kWh or kilowatt hours. So a 10kWh battery can discharge 1kW of electricity for 10 hours or 2kW per hour for 5 hours etc etc. When having that chat with your friendly battery sales person, it is vital you both have a reasonably clear grasp of your night time power usage (and your PV generation capacity) before committing to a particular brand. If you are an empty nest retired couple who hit the sack at 9pm after an early dinner and use 3kW of power after dark, it is absurd to have a 15kWh battery installed at your place. If the 6 of you blaze away until 2 am each night, it is unrealistic to think 5kWh of storage will take care of your evening energy needs. The average Australian night time consumption at 2019 is around 8kW, by the way.
Back Up: Because of the nature of the Australian electricity grid, we do get hit with blackouts from time to time. Naturally, we want to keep the lights on when this happens and give hand gestures to the neighbours (they will be able to see you). Some brands have back up, or EPS, Emergency Power Supply, as standard while others sell the EPS function as an accessory. When having that chat with your friendly storage sales person, please, when they say, “Yeah, it’ll back yer whole house, mate!” get some serious evidence of that from them and, if that function is an accessory, how much more will that cost. Some brands discharge at a rate of as little as 1.8kW per hour, some as high as 5.5kW. If you have a 10kWh battery installed and the blackout lasts all night, the lower discharge unit is probably a better bet as the big one will drain in two hours, leaving you just like the neighbours (who’s laughing now?)
Smart vs Dumb: Some brands simply send out power when your inverter asks for it, others provide a plethora of clever 21C functionality with software linked to clouds, inputs from IoT, AI learning, BOM data input – the list goes on. Ask yourself, do you really want another piece of smart computer hardware in your garage or just a tank full of free power to keeps the lights and Netflix running?
A residential PV battery can be installed at the same time as installing solar or can be retro fitted after solar has been installed. From your friendly solar installer’s point of view, getting both PV and battery at the same time is easier for him, but retro fitting a battery is, really, no big deal as far as installation is concerned. However, what IS a big deal are the regulations and installation standards associated with residential battery installations…so pay attention here.
IP Ratings: There are many battery brands now congesting the market in Australia. Very few have been developed specifically for the Australian market, so hardly any international brands understand the Oz market and our particularly retrograde compliance rules. An IP rating of 55 (IP55) means the battery can be installed outside. An IP30 rating means it has to be indoors. In Australia, ‘indoors’ means the garage (for reasons I will explain in the next chapter). If you don’t have a garage, the battery needs to be outside, on the services wall of your home sweet home, ideally not too far from your switchboard. Clearance rules apply here too however (explained in the chapter after the next chapter). Because many of these battery brands have been designed overseas, problems may arise with performance when the battery is exposed to day after relentless day of blazing sunshine on your western facing services wall, so perhaps consider another location for installation. You should be having a frank and honest discussion with your friendly battery installer about this. As well as the following points…
Fire Retardation: Australia has some unique Standards associated with building and electrical compliance, all in the name of safety and the greater good. The newly minted AS5139 has set some awkward rules regarding installing batteries and if your friendly battery installer fails to comply with these new rules, you may be breaking the law. If a battery is to be installed indoors ie the garage and if the battery is to be sitting against a stud wall ie not brick or cement then fire retardant cement sheets need to fitted to the wall (and perhaps ceiling) before the battery is installed. 600mm either side and 900mm above. If the 900mm above the battery is higher than the ceiling, the cement sheets will need to be fitted across the ceiling of the garage also out from the wall a further 600mm. These new rules have not helped the battery industry get going here in Oz and have also turned your sparkie into a chippie as well – a situation that both sparkies and chippies don’t really like the idea of. Once again, if your friendly battery sales person cannot explain these Standards in detail to you, politely show them the door, as they are not being as transparent as they should be.
Clearances: In addition to the above, certain clearance standards are in place for battery installations that relate to both indoor and outdoor installations. A battery cannot be under a switchboard or air conditioning unit for example and not butted up beside a hot water system. An honest and upstanding battery sales professional will be able to explain all of these requirements in detail you – should you ask… and you should ask.
How much do batteries cost and how long before they pay for themselves?
To date, we have not seen battery prices fall nearly as far as solar has in the last few years. It’s really difficult to predict whether they will drop in price at all, but supply and demand and competition should see the costs begin to fall sooner or later…we hope. Right now for a typical residential battery of around 10kWh, you could pay anything from $5,000 to $16,000 depending on its smartness or dumbness, quality, warranties, country of manufacture and the like. State government rebates are available in several Australian states and a worth exploring, too. Right now, in 2020, a battery purchase to supplement your PV installation and provide you more energy freedom, less reliance on the grid, future proofing from rising energy prices, greater energy security in times of environmental stresses and a step closer to total energy independence is a lifestyle or aspirational purchase rather than a return on investment one. It’s hoped this will change in the next few years, but currently, to have your friendly battery sales person tell you you’ll have an ROI in under 5 years is perhaps stretching the truth to a degree.