EU PVSEC in Paris was my very first conference related to solar energy. Since my field of study relates more to the system side of photovoltaics, I was happy to see that this conference had its fair share of talks on system research. From energy yield analysis and prediction methods to the effect of PV on the grid, even after selecting the most interesting subject to shorten the list, it was impossible to attend all the presentations. I can’t even imagine what it was like for my colleagues who study solar cells when the conference had about three times as many talks on the solar cells than it had on systems.

Although I have a lot of respect for my colleges  performing research in improving the efficiency of the solar cells, I believe that the future of the photovoltaics as a major energy producer will depend much more on the quality of the power it delivers to the grid than the-per panel output. The high variability of the solar resource, mostly due to intermittent cloud coverage, has little impact on the grid when the solar penetration levels are low. But with all the solar projects currently happening and all the home owners installing solar panels on their roofs, it won’t be long before penetration levels get to a critical point and utilities start enforcing solar installation caps. In fact, this is already happening in some regions and this is why I think it is critical to do research in this field.

I believe the way to solve this problem in the long run will be to use storage technologies. But before these technologies become reliable and affordable, intermediate solutions should be put into place to alleviate some of the problems. One of the talks at the conference discussed one of these intermediate solutions. Owen Schelenz from GE Power Conversion presented “A Novel Approach to Plant Level Voltage Control on Distribution Feeders” which demonstrated the capabilities of a novel controller developed by GE that uses reactive power to reduce the impact of a sudden rise or drop in the power output.  Basically, when a cloud passes in front of the sun, there is a dramatic change in irradiance and thus the power output from the solar panels drop accordingly. This power that was used by some load still needs to be supplied and thus, the power plant will need to compensate for this change. There are a few problems involved in this situation. First, the power plant will need to ramp-up power production and this will increase wear-and-tear on the equipment. Second, these changes affect voltage levels and in turn might damage voltage sensitive equipment. This second problem is what GE is trying to solve with its novel controller. By injecting reactive power on the grid while the power plant corrects for the variation, the power at the load appears constant and thus the voltage is much more stable.

This novel controller by GE is certainly a step in the right direction and one that may help solar in the short term. But in the long run, regulators will want more control over the power supplied by solar, and more powerful solutions will have to be developed. As the saying goes, “With great power comes great responsibility”!

FrederickCarle

Frederick Carle
MASc Candidate, 2nd Year
SUNLAB, University of Ottawa