MAILBOX: “I have been 95% off the grid for seven years and love solar power. This is the future!”

The email below was received from BizNews community member John Simpson in response to the article ‘How home batteries and inverters can impact your electricity bill: South African insights‘ published on last week.

Hi, sadly, this story is so incorrect.

Your facts are correct, but the logic and application are totally wrong and misleading. The extra cost of running an inverter and battery from an electricity usage perspective amount to a relatively insignificant amount As the equipment may only have a 95% efficiency.

Read more: SA Presidency maps out plan to end loadshedding

Your calculations are applied totally incorrectly. By way of example, suppose one had no load-shedding and used 20kwh electricity at a cost of R60. If you had load-shedding for half that time and used a battery backup, each would produce half the usage and cost R30.

The total electricity in this example is unchanged, and the cost is almost unchanged. You are arguing that it will then cost R30 to charge the battery. But you have still used the same amount of power as if there was no load-shedding?

Read more: Cape Town ‘wheeling people’ to give loadshedding, poverty and pollution another deadly blow

You are saying the cost is R60 plus R30 = R90. So your maths is perfect. But your logic is totally incorrect.

So, if you had solar panels to charge the system, then the amount of power you purchased from the supplier would drop, and your electricity bill would drop. With no panels, the amount of electricity used would be materially unchanged, and your bill would increase by a very small amount because the system is not 100% efficient. It would not increase by the amount used to charge the batteries. You are double counting and coming to a totally incorrect conclusion.

Read more: Mailbox: Renewable energy proposal – “Harness the Agulhas current”

I have been 95% off the grid for seven years and love solar power. This is the future!

Please rethink this.


Kind regards
John Simpson

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