Tag Archives: solar

Solar vs Coal – the Math

Solar, solar solar.

If Solar doesn’t work for most of the evening, how can it compete?
Wouldn’t we be better off with Coal? Isn’t coal better for generation – you know, its baseload!

Yes, its another post based of an answer to something asked on MyBB!

At first glance, you’d think so, however the math tells a different story.

As I like to do in my posts, I’ll first go over some basics

Solar PV farms are built to supply electricity at a certain price. This price per kW.h is usually awarded with an REIPP auction where vendors bid to supply a given amount of electricity – typically 100MW or less at a certain price.
The price paid is then guaranteed by the government for every kW.h supplied for a 20 year contract, typically with small escalations per year.

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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.

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