Distributed Solar Generation Interconnect Course

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Minister of Fire
Hearth Supporter
Jul 11, 2008
Northern NH
I have been mulling if I was going to keep my PE license active post retirement as my renewal date was coming up. I may need to use the license on my house build so I decided to renew which meant I needed continuing education credits. Rather than going to a CEU mill I prefer to take interesting courses so I took one on interconnection of large commercial solar arrays to the grid.

The main subject is that the original IEEE 1547 -2000 standard for interconnection of distributed generation was pretty simple, just like a small solar system, if the grid goes out of specifications, the plant disconnects. This is fine when there is only a bit of solar on the circuit but once it starts to be bigger part of the grid, its a big problem as Hawaii found out. The solution took awhile until IEEE 1547 -2018 came out and that keeps the generation on line even when the grid goes out of range of specifications and the inverters are equipped with multiple operating modes that actual improve grid power quality. In order to cover how these new standards apply to the grid, the course reviewed the operation of local distribution grids and the equipment used. I knew a lot of the equipment from my CHP career, but I understood them better and what they did during normal and abnormal grid operations.

The net result is that most utilities were "sandbagging" the addition of solar farms and using rules of thumb to limit their use on the grid. The new grid interactive inverters with their various operating modes that can improve grid power quality can mean far more solar on the grid in a lot more places. The course didnt spend any time on solar farms with batteries but they increase the potential for solar on the grid plus improve the dispatch reliability. Some states have put in place pretty powerful GIS based programs that allow developers to search what previously was utility information to find potential spots for locating large solar generation, this means a potentially faster siting process.

It always is interesting to see how media and experts lags standards like these, a lot of the issues in the news about siting solar farms is now far more of a political issue than a technical issue but the press, the government and the utilities all try to blame the technical side.

Now I need to come up with five more hours. A geothermal certification course is currently the top candidate.
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Hi peakbagger, I'm not a PE, but have a B.S.E.E. and due to the industry I am in I follow this area quite closely. I assume you are talking about newer grid-forming inverters and inverters that have the ability to control the amount of reactive power supplies to the grid. Or is it something else/newer that I'm not aware aware.

Agreed that there are no technical issues to much wider deployment of solar PV on the grid and that delays/hurdles are largely a result of entrenched interests trying to protect their future profits and/or those who lean politically against solar PV (for whatever reason) rehashing specious arguments that resonate with the vast majority of the non-technical population.

Note that I am specifically not bashing the non-technical population. Technical folks, in general, are horrible at taking their complex knowledge and distilling it into simpler, shorter bites of information that everyone else can understand and use.
I think its the same thing. They come with voltage control turned on by default so if the grid has low voltage, the inverter tries to boost it or the alternative. In addition to default voltage control, there is large "swiss army" knife of various features like VAR correction but they are turned off by default and it up to the utility to tell the generator what they want to see.

Wind Turbines had the same issue years ago, they tended to be way out on the end of the grid and could raise havoc with voltage, newer designs used a grid forming inverter so they could improve the grid operation if the utility let them.

It was interesting that about 20 states have forced the utilities to make it easier to hook in solar. In NY a developer can look down to street level circuits and get a lot of info on its potential to tie in solar using a GIS based method.
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