Click here to see a near real time view of our panels in action.
On March 27, 2004 our total power generated passed 10,000 Kilowatt/hours!!!!!!!
On June 11, 2005 our total power generated passed 20,000 Kilowatt/hours!!!!!!
On March 15, 2006 our total power generated passed 30,000 Kilowatt/hours!!!!!
On February 14, 2007 our total power generated passed 40,000 Kilowatt/hours!!!!!
On September 23, 2007 our total power generated passed 50,000 Kilowatt/hours!!!!!
On July 10, 2008 our total power generated passed 60,000 Kilowatt/hours!!!!
On November 11, 2010 our total
system power generated passed 90,000 Kilowatt/hours
The installation consists of (36) 165 watt Sharp photovoltaic panels and two SMA Sunny Boy 2500 watt inverters. Due to loses and inefficiencies, the total installation is rated 5000 watts or 5 Kilowatts. I designed my own mounting system made from Unistrut aluminum channel and custom made aluminum brackets. By using aluminum for the mounting hardware, I was able to keep the weight of the installed system lower and avoid galvanic action due to dissimilar metals (the frames of the PV panels are aluminum). I chose to have the panels separated a little in between each panel and between each row. This was done mainly for cooling in the summer and ease of maintenance. It is very important to remember that all the components on the DC side of the system be rated for DC. Sometimes these items can be hard to find.
The Sharp PV panels come with USE-2 wire with integral MultiContact connectors.
This is a UL listed wiring system. The panels just plug together. We
did have to make sure that none of the wires were exposed, since the voltage in
them can exceed 400 volts DC. We did this by making sure the wires were up
underneath the panels. I had to add some raceway for the wires to get
between sections of panels on bank 2 where they were separated by the
skylights. The inspector initially had a problem with the wiring method
until I showed him the UL listing of the panels and MultiContact
connectors. He also was going to turn down the inverter hook up because he
considered them a separately derived system. They are not since there is
no neutral connection and the inverters need AC power to operate and they are
directly connected to my main panel, they can not generate electricity if there
is not PG&E voltage present. We called his boss and his boss agreed
that I was correct. The inspector signed the permit and left with a little
of his ego bruised.
The system has no moving parts and no batteries. The only maintenance is a once a year check of the mounting brackets and the electrical connections. The estimated life of the system is more than 25 years. We hope that what we are doing will (1) pay for itself in a reasonable period of time (at the current rates we are guessing between 6 and 8 years), (2) be some small help to alleviate California's power problems and our country's dependence on oil, and (3) encourage others to do the same, (4) allow us to use our house as a showcase for selling PV installations through the company I work for, Clark Electric.
My union, the IBEW Local 332, partnered with the NPCP (see the links below) to make a group purchased of the photovoltaic panels and inverters. This allowed us to get the items at wholesale prices. The goal of this partnership is to train our unionís members in the installation of PV systems. To this end I can say it is working. I learned a lot about PV systems and their installation though my own installation (enough to know at least more than the inspector).
If you live in the Santa Clara County (CA) and are interested in a solar electric system like mine, please contact me, Vince Endter or Virgil Clark at Clark Electric, 408-988-4358.
I had calculated that we should generate 20 kWh around the shortest day of the year and 40 kWh on the longest day. On March 18th, a few days before the equinox, we generated 30kWh. It looks like I am right on with my calculations.
Interesting cloud effect: I noticed on days with cumulous clouds, when the sun would appear, the system out put jumped from 3800 watts to 5000 watts, a 31% increase. I called Sharp solar and asked about this. The cause of this they said was something they called the cloud effect. It only happens with cumulous clouds. When the sun appears next to a cumulous cloud, the cloud focuses the light from the sun increasing the suns intensity.
The effect of dust on performance. We went 4 weeks without any rain. I noticed a film of dust had covered the panels. I hosed off the panels to wash away the dust. After cleaning off the dust, I had a 7% increase in output.
|Daily Output||Monthly Output||Monthly Bill|
Jan 16, 2003 Daily output exceeded 20 kWh for the first time (20.6).
Jan 25, 2003 Total output exceeds 500 kWh
February 1, 2003 Power output exceeds 4000 watts for the first time (4100 watts).
February 2, 2003 Fist day we generated more electricity than we used.
February 23, 2003 Total output exceeds 1000 kWh.
March 25, 2003 Total energy output exceeds our usage since system installation.
Total system output from 12/12/02 to 08/302008 - 62566 kWh.
Pounds of CO2 abated - 91346
This is an equivalent to the energy (if used to generate electricity) in 5213 gallons of gasoline.
|12/12/02 - The completed installation|
|The end bracket and strut support for the end of a row of panels. One can see the 1/4" bolt and cone nut with which the bracket is connected.|
|This is another view of the end bracket. One can also see the support for the Unistrut.|
|The custom bracket that is placed between two panels.|
|There are two rows of (9) panels each that feed each inverter. These two rows are paralleled before the inverter. This requires each row to have it's own 10A DC rated fuse.|
|A view inside the combiner box showing the fuse and fuse holder installation.|
|Unistrut supports for bank 2.|
|Unistrut supports for bank 1.|
|View of bank 1. 18 PV panels..|
|View of bank 2. 18 panels. Notice the extra work to install the panels in between the skylights and the different widths of the roof.|
|These are the two SMA Sunny Boy 2500U inverters. Also in the picture are the two 600V DC disconnects and the sub panel above the inverters that I used to combine both inverter outputs so they could be wired to a single disconnect required by PG&E.|
|The disconnect required by PG&E. It must be within sight of and no more than 10' from the meter. I have a disagreement with PG$E about the necessity of this switch since the inverter can not generate electricity without PG&E voltage present. The requirement for this disconnect added about $1000 to the installation cost of the system.|
|The schematic used for our system.|
IBEW local 332
OtherCalifornia Solar Center
This page was last updated.
11/15/2010 07:56:38 PM