Newsletter No. 3


Occidental's 1 MW solar array just finished, today, it's first year of operation.  Happy 1st Birthday Solar Array!

Oxy community,

 
Occidental's 1 MW solar array just finished, today, it's first year of operation.  Happy 1st Birthday Solar Array!
 
In its first year the array produced 1.81 GWh of electrical energy.  This is a LOT of energy.  The average LADWP house uses 14.8 kWh per day so the energy produced by our array in its first year was enough to power 334 of our neighbor's houses for a whole year.  For other equivalencies, especially regarding climate change, you can punch in 1.81 GWh = 1810000 kWh here.  For instance, 1.81 GWh of green electricity, is equivalent to taking 266 cars off the road for a year.  More locally 1.81 GWh was 12.5% of the total electrical energy used by the college over the last year.  We haven't seen annual electrical usage this small since 2002.
 
On the financial side of things, our electrical bills have been lower this last year due to the energy generated by the solar array.  Every month I am able, with help from Facilities, to do a detailed and robust calculation of our savings.  Over the last year the solar array saved the college $241,000.  This is a little smaller than the $283,000 I had predicted bumping up my predicted payback period from 12 to 14 years.  Recall that the panels are warrantied for 25 years.  The payback period calculation, however, assumes a conservative 4% inflation rate for electrical rates, based on national averages.  The LADWP has been increasing rates at more than 6% for the last decade.  If I were to put 6% in we would be back to a 12 year payback.  So we will have to see.  So far the solar array has paid back 6.5% of the money we borrowed from the endowment (~$3.4M).  
 
1.81 GWh was 9% more than my simple solar model predicted.  As I said in my last email an excess might be due to sunny days, clean panels, conservative assumptions, simplistic assumptions or something else.  Understanding the output of the array is important; in order to maintain it properly we need to understand it.  To that end I am aware of 3 student proposals submitted, 2 in physics and 1 in math, to the URC.  With their help we could make some headway on this problem.
 
If you want to monitor the array yourself you can log into our AlsoEnergy website,

Login ID = oxysolar
Password = 1600solar

The app can be found, for the iPhone, at the Apple's App Store by searching for AlsoEnergy.

In other news,

1) We made it onto Google.

 
2) In October Facilities weeded around the array and cleaned all of the panels.  I did a simple analysis and found that the combination, with a little rain thrown in to confuse the matter, produced at 30% bump in our energy production.  If you are interested I'd be happy to send you a memo I wrote about this.  30% was much larger than I was expecting and got me to thinking about an optimal cleaning schedule.  Ramin Naimi, in Math, and I got talking about this one day and did manage to come up with an algorithm to maximize $.  However it doesn't include rain.  Hey, you've got to start somewhere!  Anyway the array has posed some fun and practical puzzles to solve.
 
3) On 3 separate occasions we popped a fuse on the big 500 kW inverter.  The reason for this is still under investigation.  It is worrisome!
 
4) Martifer went bankrupt!  I am assured this is just an opportunity to get their finances in order.  In fact Martifer was up on the hill just a few weeks ago trying to track down the fuse problem.
 
5) In October the DWP shut us down for a couple of days for electrical work nearby.  In total I estimate we were down for the equivalent of 11 full array days or about 3% of the year.  97% uptime isn't too bad.
 
6) On December 13th Facilities reported one of the panels had been broken.  This was fixed within a day.  It appeared to be some sort of projectile but we could never find it.
 

7) The solar array cannot help us in a power outage, such as the one we experienced yesterday.  In fact, for safety reasons, if the normal AC shuts down the array's inverters automatically cut power coming from the array.

 
Enjoy the sun because it produces lots of electricity for us but enjoy the rain too because it keeps our panels clean.