How Safe are Solar Battery Storage Systems?
For those of you who are keen to dive into the nitty-gritty science, this report by the Clean Energy Council contains everything you'd ever need to know.
For everyone else, here's an overview:
Battery storage, regardless of whether it's lithium ion, lead acid, flow or aqueous hybrid ion, is perfectly safe if it is installed by an accredited electrician and properly maintained.
However, the inherent safety behind battery storage does vary between competing technologies:
Lead acid is generally safe, and easily recyclable. To quote from the Clean Energy Council report linked above:
"Lead-acid batteries are generally safe, but do emit a corrosive and explosive mix of hydrogen and oxygen gases during the final stages of charging. If these gases are not vented appropriately in accordance with regulations they can potentially ignite if exposed to a spark or flame. Hence, it is essential that this type of battery is located in a well-ventilated enclosure or place. Another hazard is that the sulfuric acid electrolyte can cause serious burns if spilt.
These are risks that, if managed by appropriate care and use of the batteries, will not lead to a dangerous situation; they are much like the risks associated with driving a petrol-fuelled car, which remains a useful and prevalent technology in daily life."
Lithium ion poses a fire hazard if not installed properly, or if you use inferior quality batteries. This is due to the chemistry behind lithium-ion batteries making them prone to 'thermal runaway' (aka bursting into flames) if they are damaged or if they overheat.
Because 'lithium ion' is an umbrella term that describes a wide variety of lithium chemistries (like lithium ion phosphate and lithium titanate), it's important to note that some types of lithium ion batteries are much safer than others. Tesla's Powerwall battery also boasts a special design that seals off any thermally unstable cells if they pose a thermal runaway risk, which is why they're rated for both outdoor and indoor installations.
Lithium ion batteries are very difficult to dispose of/recycle, making them hazardous from an environmental perspective.
Flow batteries are much more environmentally friendly, and have a very low fire risk due to the inherent chemistry behind the zinc-bromide electrolyte, which is essentially a fire retardant. They're also very easy to recycle.
Salt water batteries are non-toxic, non-flammable, and non-explosive. Their chemistry is inherently safe and not capable of thermal runaway. The batteries are also entirely touch-safe, and environmentally friendly to recycle.
In short? Don't skimp on battery quality or installation costs. Get the job done right, and your battery storage system will last decades.