Sunday, July 25, 2010

Experience with Our Solar PV System

Our Solar Photovoltaic System Facts:
Size: 24 SunPower panels at 215 Watts each, for 5.16 kiloWatts total
Roof Orientation: South Southwest
Installation Date: January 27, 2007
Peak AC Power Output: approx 4,000 W
Peak AC Power Output for a full sun day: 33 kWh
Our Annual Power Usage: 
2005: 10,278 kWh (base year for system sizing calculation)
2007: 7,738 kWh (year of system installation)
2009: 7,051 kWh
Power Production in Excess of Usage, 36 month total: 3,009 kWh 
Percentage Power Production to Usage, 36 month total: 113.5%
Total Cost Before Incentives and Credits: $39,336 ($7.62/Watt)
State Rebate Paid to Installer: $11,837
Net Out of Pocket Cost before Federal Credit: $27,499
Federal Tax Credit: $2,000 (maximum limit at that time)
Net Cost to Homeowner: $25,499

So how has our solar electric power system worked out for us?  In a word, "Fine".

The installation was completed in a couple of days.  The installers removed our clay roof tiles in the area where the panels would be installed, and they installed a new composition tile roof system below the position of the panels.

Things went smoothly, aside from a few misplaced bolts that we saw poking through our wood beam bedroom ceiling, and a broken window, all of which the installer quickly fixed.  Our utility, SCE, replaced our old electric meter with a new digital one.

Living with a solar electric system is simplicity itself.  We can ignore the system.  It will produce power when the sun is shining, and our electric meter will run backwards.  When it is cloudy or at night, our meter may run forwards or backwards.  The system requires no maintenance or monitoring.  To improve the performance of the panels, they can be cleaned with soap and water perhaps twice per year.

Issues:  Pretty big ones actually.  Before I go into this, I will say that everything is fine now and our installer has taken care of the problems.  We are happy with our system.  We and the installer learned a lot about some roofing issues from our experience, but we certainly had some worries and emotional concerns through the process.

What happened?  RAIN LEAKS!!  Our system was installed at the end of January, 2007.  We woke up on the morning of the first rain storm to find our master bedroom ceiling leaking in 20 places!  Yes, on our bed, on the carpet, everywhere that a lag bolt pierced the roof to hold the panel mounting racks, there was a leak.

We are patient, trusting people, so when the installers sent out a crew to find the leaks and fix them with mastic, we expected that to solve the problem.  It didn't. They came out SEVEN times for attempted repairs before it was fixed.  My poor wife Carol was so disappointed.  It felt to her that we had naively agreed to turn our home over to inexperienced people and that they had broken it.

What was the problem?  The original roof modification plan was poor.  When they put the new composition roof in the area where the tiles were removed, they left the area that was still tiled untouched.  So water ran down the tiles and onto the roof below and got underneath the composition roof tiles that they had installed, then it found its way to the lag bolts that penetrated the roof and the water leaked inside.  Putting mastic into the holes from above did almost nothing.  Carol had anticipated this problem from the beginning, but the company was reassuring, so we went ahead with their plan.  We now know better.

When I finally got tired of letting them try the same solution, I called the president of the company.  Within a few days, a supervisor came out and authorized the repair guys to remove all of the roof tiles and put on a SECOND new composition roof on top of the first one, and to place it edge to edge and top to bottom on the roof.

That finally worked.  There were one or two slight leaks after that, but they were quickly solved.

The moral of the story:  Make sure that the company you choose has experienced roofing experts on the staff.  The electrical part of the installation is important, but our experience is that the roofing piece is more important. And if they suggest an unusual sounding installation, question it until you are completely satisfied that they know what they are doing.

Next blog entry:  Things we've learned about solar.