Concentrator Photovoltatic

Conentrator Photovoltaic (CPV) is very similar to the PV in that it uses the same physical process to convert photons into electricity, however it does this by concentrating the sunlight into a very small, and efficient multi-junction solar cell using lenses or mirrors.

To help keep the efficiency as high as possible these arrays are typically installed on dual axis trackers to point the array directly as the sun.

Concentrated Solar Power

Concentrated Solar Power (CSP) is completely different from CPV or PV, in fact the only thing that is the same is that it uses the sun for energy.

CSP works by directing the solar energy into a point (or a series of points) to heat a liquid (or a solid to a liquid) and then this liquid is used to heat water to convert it to steam. This steam is converted to electrical energy using similar thermal turbines as coal, oil, etc.

CSP sites are up to 50% efficient, however they require specific sites to set up and work.

The Ivanpah Solar Power Facility, image by Doc Searls

The Ivanpah Solar Power Facility is a 392MW CSP that is expected to produce 940,000 MWH per year. [3]

Photovoltaic Solar

Finally we get to photovoltaic (PV) solar, which is the one that the rest of the series will be concentrating on. The reason that PV solar is so popular is that it attacks the problem in a simplier way, its a hammer for every nail.

CPV is great if you only have a small area and need to have reliable energy in in a disconnected site. For the same panel area you can extract much more energy than with PV. A CPV system can have an efficiency of 44%, where typical PV cells, at cool temperatures, are half that at 22%.

CSP is a different beast where it can only be installed in very specific sites.

PV may have a lower efficiency, but it can be installed almost anywhere, it is a lot cheaper and lighter than CPV, and there is competition in almost every market in around the world. If you want to have a little more system efficiency you can add trackers, dual or single, and since the panels are much lighter you can add a lot more to them for cheaper.

They can be of almost any size, from the small ones in your calculator, to any array that is 100s of MW.

Why Solar?

Why not?

That's not a great answer, but here it is. I don't think that solar is going to be the holy grail that a lot of people think, at least in the next 50y, however it is a very powerful tool to help reduce our reliance on carbon emitting fuel sources.

It is also a technology that allows people to feel like they are part of the solution by installing panels at home and work. That may lead to support to the policy decisions that need to be made at a government level to make the fixes we need.

The next few articles will be covering how solar system design happens, what you need to know etc.

I'm sure after that I will have a few articles about why solar is going to cause a lot of challenges to the operation of the utility grid over the next decade and some of the things that we, as a society, will need to figure out to make everything work.

I don't think the answer is "microgrids", but rather more transmission, something that is harder than an apartment building in a 60s era suburb, but it is the solution if we want variable energy sources as our main electricity source.

Conclusion

This was a short introduction to solar design and the various types of solar systems. From this point we will be covering PV Solar, but if you would like me to cover CSP or CPV in more detail let me know on twitter and I will add it to the calendar.

Sources