Lead acid batteries and solar battery storage

Bank of batteries

A bank of lead-acid batteries

Lead acid batteries are the most common form of solar battery storage currently on the market.

Battle-tested, thousands of Australians have used banks of lead-acid batteries with solar electricity to remove their need to be connected to the traditional electricity grid.

The most common setup of lead acid batteries you'll see is usually some kind of rural household installing a bank of batteries + solar panels, because it's cheaper than paying $30,000 to get the grid extended all the way to their house.

However, some Australians who have normal access to the grid still elect to go off-grid with a big bank of lead acid batteries. As I explain in another article about off-grid solar systems, from an economic point of view this is sheer madness for an average Aussie home. If you have a super efficient home that uses less than 5kWh per day, leaving the grid can make more sense. But for the average Australian household using more than 20kWh of electricity per day, you would need to spend $30,000-$50,000 to go off grid reliably.

Here's some specs about lead acid battery systems:

They will give you 1000-3000 cycles at about 60% depth of discharge. In plain English: You can discharge them 60% 1000-3000 times depending on the quality (price!) of the batteries. So if you are discharging 60% every day, they'll last 3-8 years.

BUT – these figures are usually quoted at a 20 degrees C ambient temperature. If your battery storage area gets hotter than this, the performance will be worse.

How much will a lead acid + solar setup cost?

It all depends on how many batteries you want. But the short answer is: you'll pay double compared to a hybrid solar system.

At the time of writing, a good 3kW solar system costs about $5,000 installed. If you want to add 4kWh of usable storage to this, expect to pay about $10,000 for the complete system. 4kWh of electricity storage will get an efficient house through the night.

The average Aussie home is not that efficient unfortunately – so you may need a bigger system. A 5kW solar system without batteries will currently cost you about $8,000 installed. If you add 8kWh of usable storage, the total price would be closer to $18,000. This would get an average home through the night.

(I'll be the first to admit that $15,000+ is a lot of money for the average Australian to find, even if they're extremely keen on adding battery storage to their solar PV system. My recommendation is for people to wait a year or two for battery prices to drop further before they consider adding them to their homes.)

A note on the future of lead acid technology

As you might have guessed from this article, I personally believe that traditional lead acid battery technology is more or less obsolete for solar battery storage purposes. However, there is one special technology that may bring lead acid back into vogue for solar battery storage – it's called the Ecoult Ultrabattery. We haven't carried out a review of it as yet, but it promises to give all other forms of battery storage a run for their money, in terms of both performance and cost.

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