By Larry Howe
How many rooftop solar installations are there in Texas? Is the number growing? Where do you find this information? How current is the data? How often is it updated?
The Texas Solar Energy Society (TXSES) estimates, at a minimum, there were over 17,000 “behind the meter” solar PV installations across the state at the end of 2015. “Behind-the-meter” means solar PV generation installed to generate electricity on the customer side of the meter to provide electricity supply for the customer’s load. This type of distributed generation installation includes both solar PV installed on rooftops of homes and businesses, as well as ground mounted systems. For simplicity, I will refer to behind-the-meter installations as rooftop installations for the remainder of this article.
To date, there isn’t one place to find data on the number of rooftop installations in cities and communities across Texas (This is changing, more on this later.). We have been piecing together information from various sources to try to compile a total for the state. And the good news is the number is continuing to grow! Note: Some states do provide rooftop solar installation counts and installed capacity – see www.californiasolarstatistics.ca.gov .
Until late 2015, we had been using three main sources of information for rooftop installations. These sources are (1) Solar San Antonio and (2) Austin Energy, both large metro areas with growing rooftop installations serviced by municipal electric utilities; and (3) load profile type count data from the deregulated market areas of the state through ERCOT, our Texas grid operator. Using these three sources, complied data indicated 10,648 and 14,606 installations at the end of 2014 and 2015 respectively. While this provided a decent estimate, it did not include data from the large number of electric co-ops and other municipal electric utilities across the state.
Then in December 2015, the Energy Information Administration (EIA), published an article titled, “EIA electricity data now includes estimated small-scale solar PV capacity and generation” www.eia.gov/todayinenergy/detail.cfm?id=23972. For the long term, this is very encouraging! After a conversation with a project manager at EIA, we obtained an understanding that their data is constructed from (1) the annual survey Form EIA-861 which collects this data from all respondents, combined with (2) statistical sampling from the monthly Form EIA-826 which is a cutoff sample drawn from the annual survey. Since the EIA regularly provides data on electricity sales and generation, their objective in tracking small-scale solar PV installations is to use the number of installations and the installed capacity of these systems to develop monthly estimates for the mega-watt-hours (MWHs) generated by these systems.
The first data from utility respondents for the small-scale solar was compiled in 1Q-2015 for the end of 2014 data. Doing some initial parsing of the annual survey data, and comparing with the other three data sources we had, we identified an additional 2,444 installations. Therefore, we now estimate that in Texas we had a minimum of 13, 297 installations and the end of 2014 and 17,050 at the end of 2015. Again, we estimate these are minimums because of the “snapshot” timing of the data. For example, the “end of 2015” data includes the following data “snapshots” in time:
- 7,088 from 12/15/2015 ERCOT load profile counts
- 4,670 from Nov 2015 Austin Energy Solar Energy Monthly Report
- 2,848 from Solar San Antonio, as of May 2015
- 2,444 from an extract of the end of 2014 Form EIA-861
The EIA manager that developed the “small-solar” tracking process indicated that over the next reporting cycles (i.e. next couple of years), the data will become more accurate and complete. Electric utilities have been providing electricity sales and generation data to the EIA for decades. Their internal processes to report this data are mature and stable. However, this is not yet the case for this new distributed generation reporting, but will be over time.
So in the next few years, the EIA small-solar reporting should become a good annual source for the number of installations, the capacity, and the estimated MWHs generation all across the US. Until then, TXSES will continue to attempt to track and report what it determines to be a best estimate.
And we could use your help! Ask your city and/or community to track and publically report solar installations at their locations at least on an annual basis, including the total number of installations and the total installed solar PV capacity grouped by residential and non-residential distributed generation. We can then use this data to collaborate with the EIA and other organizations to further improve the tracking of our growing rooftop solar installations across Texas!
Useful References:
- http://www.ercot.com/mktinfo/loadprofile, see description for “Profile Type Counts”
- https://austinenergy.com/wps/portal/ae/about/reports-and-data-library/customer-energy-solutions-program-updates, see “Download the Solar Monthly Report (pdf)”
- http://buildsagreen.org/, Solar San Antonio now part of Build SA Green, contact for rooftop solar installation data
- “EIA electricity data now include estimated small-scale solar PV capacity and generation” (see www.eia.gov/todayinenergy/detail.cfm?id=23972).
Larry Howe is a TXSES board member and co-founder of Solar Plano Advocates. He has tirelessly promoted solar in his community through Solarize Plano, numerous presentations and workshops, and Solar Car Kits for Kids. He is also involved with TXSES’s North Texas chapter NTREG.
As a tie in to this article, NTREG’s members spearheaded a remarkable grassroots effort to count the rooftop installations in their region by pulling information from electrical permitting departments of 160+ government agencies. You may read the white paper here, where 2,167 installations were documented by the close of 2014. At the end of 2015, there were 4,467.