Thoughts on Solar

The California Solar Initiative (CSI) is responsible for overseeing solar rebates for California’s three Investor Owned Utilities (IOUs): PG&E, SCE and SDG&E, and in that role the CSI program collects some very interesting data.  As we have in the past, we decided to dip into the data from the first half of this year to gain some insights into the State of Solar in California.  Over the next several days we will be reporting on what we have learned - and there are some very surprising things in here to be sure!

Overview & Methodology

A word first about how we processed the CSI data.  We downloaded the most recent active data set as of this writing (the August 24, 2011 data set to be precise) and parsed it into Excel.  Since we were only concerned about systems in our service area, we excerpted out just the data from SCE.  To narrow our focus more, we wanted to only look at applications that had significant status during the first half of this year.  The CSI data has a host of date fields - we took the latest of the fields ranging from First Reservation Date to First Completed Date as our Status Date and excerpted those that fell between 1/1/2011 and 6/30/2011 - a total of 6,306 data points.

That’s a fair amount of data but it necessarily omits any data at all from the municipal utilities such as Pasadena Water & Power (where we do much of our work) or LADWP.  Unfortunately, none of the munis make their program data generally available - which is particularly odd given that the local residents actually own those utilities (and thus, their data) - but that is a topic for another day.

Finally, for the purpose of these posts, all system sizes are reported in CSI Rating AC Watts (to account for differences in equipment choice and system design) as opposed to DC (or nameplate) Watts.

What can we say about those 6,306 projects?  Collectively they account for 164.7 MW of new solar power at a total installed cost of just over $1 billion - with incentive amounts totaling $219 million - roughly 21% of the installed cost.  Unfortunately, not all of those are built - or even ever will be.  Fully 11% (698) of those projects have the status ‘Delisted’ - meaning that they have been cancelled for one reason or another.  Those delisted projects account for 37.8 MW of potential solar power that presumably will never see the sun.  (Do some installation companies have a significantly higher rate of “delisted” systems?  We will answer that question in a subsequent post - stay tuned!)

The remaining 5,608 are split between “Installed” and “Pending” with 55.8% (3,131) installed and 44.2% (2,477) pending.  Breaking that down a little more, the installed projects account for  33.8 MW worth $240.1 million with incentive amounts totaling $57.1 million.  In contrast, the pending projects account for almost three times as much capacity at 93 MW worth $575.8 million with incentive amounts totaling $120.6 million.  (That is, nearly three times the to-be-installed solar cpacity for roughly twice the rebate dollars.)  On average, installed projects cost $7.09/Watt whereas pending projects cost $6.19/Watt - a positive trend for consumers since it shows the cost of solar power systems declining over time.

Does Bigger = Lower Cost?

Finally, for today, let’s examine whether the data supports the notion of solar economy of scale - that is, as system size increases does the installed cost/Watt decline?  To get a handle on that, we took two different cuts through our data set - “small” installed or pending systems <10 kW, and “large” systems ranging between 10 kW and 1MW.

First, here’s the graph for the “small” systems (consisting of 4,992 installed or pending systems - click on the graph to view full size).  As the trend line makes clear, larger systems really do drive down costs - decreasing from over $10/Watt at the small end of the range to just above $6/Watt for systems around 10 kW.

Another interesting observation from this graph are the outliers - with some data points below $3.00/Watt (mostly from self-installed system) all the way up to nearly $18/Watt!!! (We will have way more to say about those data points - and who is responsible for them - later in this series.)

If we now look at larger systems - those between 10 kW and 1MW - our data set has 587 such systems and again, the trend line shows the decline in system costs as system size increases.  (Note, because there is such a huge range in system sizes on this graph, we plotted the system size on a log scale.)  Some of these outliers are also pretty curious - a 200 kW system coming in at over $14/Watt?

Of course, this data is showing what happens when an individual project gets larger and there the trend is clear.  One might well ask, does the same trend apply to larger installation companies?  In other words, as a company has more and more installs, does that economy of scale translate into lower costs for the end consumer?  That’s a very interesting question and the answer - coming in our next post - just might surprise, or maybe even disturb you.

If there are some other cuts of this data that you would like to see, just let us know in the comments.  Trust me, we are just getting started!