Reading previous post one could remark that a 33% growth in photovoltaics (PV) is already an excellent result and rather close to 50% anyway, so what is the big deal about the IEA inflating a 33% growth to 50%?
I think that none of the two numbers is representative for the impact PV has on energy use, but let me first show the story as it is brought. This is how PV growth looks like according the BP Statistical Review of World Energy 2017:
This looks quite impressive, even when PV grew “only” 33% in the last year. At first glance this seems to be a sign that PV is expanding rapidly. According tot the IEA news story, PV is growing stronger than other energy sources (in installed capacity). Which is mathematically true, but how relevant is it in the bigger picture?
When we talk about PV, then we talk about electricity generation. However …
Installed capacity doesn’t equal actual electrical output
A 1 MW solar field doesn’t produce 1 MWh. Solar panels only work when the sun shines, in the morning it starts weak, gradually increasing and delivering a peak around noon, then gradually decrease in output until sundown. It will not surprise anyone that there is no output at night. At our latitute, there is also a seasonal cycle in which there is a lot electricity generation in summer and considerably less in winter.
This means that those panels will not produce electricity equal to their installed capacity, the output will obviously be much smaller than that.
In our region the capacity factor of PV is about 10%, meaning that a 1 MW installation will produce on average 0.1 MW over a year. Calculated from the BP data, the capacity factor of PV worldwide is about 11 – 12%. This is global solar production versus global installed capacity from 2006 – 2016 according to the BP data:
The rise of that orange line (actual solar electricity production) looks a lot less impressive that the much cheered rise of the blue line (installed capacity).
Imagine that someone is bragging about the huge increase of the blue line, yet doesn’t tell that what is produced by this installed capacity is just the orange line.
Looking closer, there is even more…
PV electricity generation is only a small part of total electricity generation
Look at the orange line (solar output) and the blue line (installed capacity solar) compared to total electricity output (grey line):
That orange line is shrinking quite a lot over those three graphs until now. But it is not over yet…
Electricity is only part of total energy consumption
In our region, electricity consumption is only about 20% of our total energy consumption. So, at this point we are talking about only a 12% fraction (share of production within installed capacity) of a tiny fraction (share of solar in electricity consumption) of a small fraction (share electricity within total energy consumption). When we directly compare solar energy consumption with primary energy consumption, then we get this:
|Year||Primary energy consumption (Mtoe)||Solar energy consumption (Mtoe)||Share solar in primary consumption (%)|
The share of PV in the primary energy consumption is definitely increasing, but it stays well below 1%. There is indeed a 30% increase from 2015 compared to 2016, but it is a 30% increase from a small number, which gives us another small number. This is how it looks like in a graph:
For solar energy consumption, look very carefully at the bottom of the graph. Hint: it is not the x-axis that is orange…
That steeply rising trend is flattening quite quickly when we widen the perspective. We started on top with a sharply rising line that got a lot of people cheering, culminating in a line that is indistinguishable from the x-axis, let alone that one could notice the increase.
But then, isn’t solar on the rise, therefor making some progress, albeit still very little right now? True, but:
Solar energy growth is smaller than total energy consumption growth
Solar energy consumption increases, but total energy consumption is increasing too. So how much is the increase of solar energy each year and how does this compare with the increase of primary energy consumption? Calculating the increase of one year compared to the previous for primary energy consumption and the same for solar energy then we get this:
|Year||Primary energy consumption (Mtoe)||Solar energy consumption (Mtoe)||Primary energy consumption (Mtoe)||Solar energy consumption (Mtoe)||Share Growth solar vs growth primary energy (%)|
This is how it looks in a graph:
There are several things to notice in this graph.
- The growth in primary energy consumption is much higher than the growth of solar energy consumption, except for 2009 when primary energy consumption crashed (the financial crisis), when solar energy consumption kept it pace. In 2010 there was a sudden jump in primary energy consumption (which confirms that primary energy use is a function of how the economy is doing).
- The solar energy consumption is steadily rising, yet stays firmly glued to the x-axis, only to get somewhat loose from it near the end.
- The three last years, the growth of solar energy is around 10 – 11% of the growth of primary energy consumption (2014: 10.83%, 2015: 11.70% and 2016: 10.16%), while before that the growth in primary energy consumption seems to be getting smaller.
Okay, this is only solar. What about the other alternative energy sources? In a comment on previous post, reader poitsplace gave the remark that the growth in renewables is outpaced by the growth of total energy consumption. This got me more curious how the growth of alternative energy consumption (solar, wind, biomass and hydro together) would compare to the growth of primary energy consumption. Would the growth of renewables compensate for the growth of total energy use or not?
It was a bit more difficult to compare, there was no compilation of several years in the last BP report and I had to search several BP statistical review reports to find the numbers. Since I wanted this post already up several days ago, I only went for the last four reports: 2014, 2015, 2016 and 2017.
The growth of renewables consumption compared to the growth of primary energy consumption in that period was:
|Year||Primary energy consumption (Mtoe)||Renewables energy consumption (Mtoe)||Primary energy consumption (Mtoe)||Renewables energy consumption (Mtoe)||Share growth renewables in growth primary (%)|
Also here, the last three years are in the same ballpark.
The growth in PV can’t even keep up with the pace of the growth in energy consumption. Even if we add the other alternative energy sources (wind, biomass and hydro).
After all these calculations with the BP data, I can only conclude that bragging about the growth of installed capacity of solar is quite meaningless. the focus on the growth in solar installed capacity gives the impression that it has more impact than it actually has.
They seems to forgot that:
- installed capacity of solar installations doesn’t equal actual output
- PV is only a a small part of total electricity consumption
- electricity consumption is only a part of total energy consumption
- growth of PV energy consumption (even renewables energy consumption) is surpassed by the growth of total energy consumption.
In the end, the little energy that is generated by that installed capacity is neglectable in our total energy consumption. Which is quite different from what the cheering “50% growth” and “birth of a new era in solar PV” claims seem to suggest.