Category Archives: Talk is Cheap

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.

Continue reading

Why is there Load Shedding at night (if we have plenty of extra capacity)

I was asked this as a followup on MyBB to my previous post about EV Cars and Load Shedding at night.

It’s a great question.

Why is there load shedding at night?

Eskom has a generation capacity of roughly 45GW in total.
Due to decades of neglect, horrifically bad decision making, and outright theft in some cases, this generation capacity is now closer to 30GW; sometimes even less.

What does generation capacity have to do with anything though?

This is easily answered by looking at demand. Sigh, I hear you say. What’s demand?

Demand is the counterpart to capacity. Demand is the amount of power we need to supply at a given time point.
Luckily this is fairly predictable on a daily weekly or monthly basis, and usually measured for time periods between daytime, evening and night.

Continue reading

Feasibility of Electric Cars in a Load Shed SA

One thing I’ve continually had to refute is whether we could support EV’s on Eskom’s grid in South Africa.
Yes, even with our current load shedding woes, it won’t be an issue, has long been my answer.

So, with that in mind, let’s put my money where my mouth is, and do some basic math to prove this.

I’ll start – let’s hand wave, and convert 500,000 cars to EV.

500,000 EV’s – woohoo! Go SA. 

To work out how much extra power is going to be needed by Eskom, we first need to work out a few things. Assumptions are a good thing to start with, so let’s make some of those..

As I’ve stated previously (and if you look at some of my previous posts, referenced with data), the average car journey in SA is 40km/day. Let’s use that as our first assumption.

Continue reading