Tag Archives: math

Tesla Powerwall Payback Math for South Africa

The Tesla PowerWall is finally becoming available in South Africa, so I thought I’d do some “30% for math” calculations to work out payback periods.

This post is mostly inspired by the comments here – http://mybroadband.co.za/news/energy/154888-here-are-the-tesla-powerwall-systems-you-can-buy-in-south-africa.html

Thanks to MacAfrican for the criticism in my comments, otherwise I’d be too lazy to do this post 🙂

Onto the math –

Predicted cost at the moment for a daily use PowerWall is $4000.
Rand is currently hovering at R16 (lets hope Zuma doesn’t open his mouth in the near future, as that historically has lead to large drops in Rand values).

Continue reading

Eskom / Municipality vs Solar pricing Maths.

One of the age old questions I get asked is this – Does solar make cents(sic)?
The smartass answer is of course “it depends”.

Eskom is fast turning that answer into “extremely well” though.

Looking at the math, the average household with say 1100KW usage a month or R1800 a month average bill in Cape Town pays these rates:

600KW @ 1.56 = R936
500KW @ 1.86 = R930 (over 600KW is billed at higher rates)

Monthly thats R1866. Lets round that down to R1800 for ease of use.

1100KW / month is 36KW / day.

36KW daily usage = 1.5KW/hr on average. Ouch.

Continue reading