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Community Batteries - Synergy Powerbank

 

WA Energy minister Bill Johnston announced on the 9th April 2020 an exciting new plan to end fossil fuel power generation in WA, and part of that plan includes batteries to store surplus solar.

 

Unlike other states, this plan does not involve offering people a rebate on their own battery, rather it is designed around very large batteries like the one pictured below that are shared by the local community.

 

It works like this.

 

Let's say that your solar makes 25 kWh of power a day, almost all of it between 8am and 4pm.

 

Your house uses up 10kWh of that solar production during those hours and the other 15kWh is sold back to Synergy for 7.13 cents per kWh. Then after the sun has gone down you buy back 10kWh of solar from Synergy at 28.82 cents. That's how things work right now.

 

Synergy then install a battery in your neighbourhood and invite you to connect to it. Initially they only you allow you to store 8kWh of your surplus per day in the battery, which you do, and you draw it back out at night.

 

Synergy charge you $1.90 a day for your 8kWh of battery use which works out at 23.8 cents per kWh.

 

So, you've been given 7.13 cents and paid 23.8 cents, so you end up paying 16.67 cents for each of those 8 kWhs of night time power. That stacks up very nicely compared to the current situation where you get paid 7.13 cents in the morning but buy it back at night for 28.82 cents, making a net price of 21.69 cents per kWh. The new battery scheme is saving you 5 cents for each of those 8 kWh and it cost you nothing. Fantastic.

 

The above maths is based on Synergy's A1 tariff where you pay a flat rate of 28.82 cents per kWh 24 hours a day. To make the battery mathematics look more appealing, Synergy offer their Smart Home Plan which has different tariffs through the day. Very cheap in the middle of the night (15.1 cents), pretty much the same as A1 for weekends and 7am to 3pm weekdays (28.7 cents) and VERY expensive 3pm to 9pm (54.8 cents).

 

Now your night time savings look wonderful with 7.13 cents paid to you first and then a saving of 54.8 cents for each of those 8kWh and you only had to pay 23.8kWh. So you are up 26 cents per kWh.

 

Of course that's really just smoke and mirrors and remember that once you've gone through your 8kWh of storage you will be paying 54.8 cents per kWh of power your home uses until after 9pm.

 

Not sure whether we will be given the choice to stay on the A1 tariff, but if we are, then there's still going to be a 40 cents a day benefit, or $146 a year.

 

Compare that to getting your own battery

We assume you have solar already, and were wise enough to purchase a battery capable inverter (often called hybrids) with its smart meter. We sell lots of them, with Huawei being the most popular.

 

A battery inverter is plug and play ready for a battery and the typical cost for 10kWh of battery is between $6,000 and $8,000. Let's split the difference and call it $7,000.

 

You lose out on the 7.13 cents because you are storing the power in a battery not selling it to Synergy (or at least you are storing 10kWh of your surplus). You are saving 28.82 cents at night per kWh so you are 21.69 cents per kWh ahead or $2.17 a day. That's $792 a year so you won't get your money back on the battery for 10 years which is the typical warranteed life of the battery.

 

However, if the A1 tariff goes and the Smart Home Plan is forced on all of us paying 54.8 cents at night then the home battery equation becomes very interesting indeed. If you used up all 10kWh of the battery power each night you would see a benefit of $1740 a year and the battery is paid off in just four years and then a minimum of six years profit of $1,740 a year. Now that IS worth doing.

 

 

 

Why not give home owners a battery subsidy?

At this stage, Minister Johnston has ruled that option out. No explanation given.

 

 

 

 

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