‘Tracking the Sun’ Report from LBNL

The 2019 Tracking the Sun report covers distributed PV systems installed in the US in 2018 [1].  This is a real-deal, actual report based on data recorded for more than a million installations over the last 20 years.

“Distributed” PV is defined as non-utility installations, i.e., homes, businesses, and campuses.  (There is a separate report on Utility-Scale Solar [2].) These systems are trending larger, more efficient, and a small but increasing percentage have battery storage.  As noted elsewhere, the ‘loading’ is steadily increasing, at least for non-residential installations.

The price per Watt of installed capability fell 5% or more over the year with considerable variability. This continues a long term trend.  However, much of this decrease is offset by the elimination of subsidies and incentives.  Price decreases in this study are slowing, though.

It is good to have these authoritative reports not only public but well documented.  (I am so, so tired of ‘reports’ that have no explanation of the methodology.  A waste of perfectly good photons, IMO.)

This report has it limits.  The report makes clear that the sample is incomplete: IL not there, TX and FL likely under reported.  CA and NY are heavily reported.  These sampling issues may mean that details of the size and cost statistics are a bit off.  But I’m pretty sure that the main trends and overall statistics are pretty well represented.

One funny thing is that the report seems to be totally focused on new installations.  With data going back 20 years, we can be confident that many of the older systems have been shutdown or are only partly operational.  So boasting about “1.6 million” systems is definitely misleading!

And obviously, everybody knows that the total cost of operation over the lifetime of the system is at least as important as the installation cost.  This report has nothing much to say about these systems over time.

Another point occured to me.

Reading this report and the companion “Utility scale” report, I am not sure exactly where “community solar” projects would appear in this data.  Here I’m thinking of small scale local installations owned by the users (who might be both residential and non-residential). These seem to fall in the cracks of the report’s definitions.  The system could be located in a non-residential location, but might serve residences and/or businesses.  The technology is going to be similar to home or business systems, though they may be operated by third parties.  But the ‘third party’ may be a cooperative or local corporation owned by the consumers.

Even the basic “small” versus “large” vs “utility” criteria (up to 100kW, 100-5000kW, over 5000kW) are hard to interpret.  The overall array might be large, but it is shared out in what might be small slices for many owners.  So, it may be purchased and operated in ‘small’ ways, even as the infrastructure becomes ‘large’.

Essentially, community solar mixes the technical and business models in a way that doesn’t fit the report categorizes things.

I strongly suspect that there aren’t very many such coops at this time, though there is considerable interest in some places.  It seems to me that this survey might want to carefully consider the definitions if community solar grows in the future, as I hope it will.

  1. Galen Barbose and Naïm Darghouth, Tracking the Sun: Pricing and Design Trends for Distributed Photovoltaic Systems in the United States. Lawrence Berkeley National Laboratory, Berkeley, 2019. https://emp.lbl.gov/tracking-the-sun/
  2. Mark Bolinger, Joachim Seel, and Dana Robson, Utility-Scale Solar: Empirical Trends in Project Technology, Cost, Performance, and PPA Pricing in the United States –2019 Edition. Lawrence Berkeley National Laboratory, Berkeley, 2019. https://emp.lbl.gov/utility-scale-solar/


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