As I alluded in my last post, my Friday and Saturday this week was spent doing something besides cycling.  I was given a very valuable and highly sought after opportunity to work on my first solar energy installation thanks to Jim Duncan of North Texas Renewable Energy, Inc.  Jim started in the solar electric installation business in 1994 and has a proven track record and reputation for quality work.  I recently completed a NABCEP certification in Solar PV system design/installation in June.  I could think of no one better to help me expand on that knowledge with practical hands-on experience.
     The system we installed was a 4.2kW grid-tied system (solar panel STC rating) located on a residence in Carrollton.  The roof was of standing metal seam construction covering what used to be an open patio.  It was relatively flat so that made work on this first project much easier.  Aluminum railing made by Unirac was fastened to the seams before I arrived Friday morning.  I helped my work-mates, Shawn and Walt, carry panels up to the roof and connect the first few to the racks with special clamps.  Below you can see all 20 panels in place with Jim about to connect them to the wiring leading down to the inverter.  The blankets are used to cut some of the current to help reduce the risk of electrical shock.

 

      While Walt and Shawn continued installing and connecting the panels, I helped Jim pull wires through the conduit running around the edge of the house to the inverter, fuse, meter and disconnect boxes.  Below, the conduit on the left brings in the PV DC (~330 VDC, ~9.2A) to the Solectria PVI 4000 inverter box (top).  There, it runs through fuses and a disconnect built into the inverter.  The inverter converts the DC voltage and current coming from the solar panels to a regulated 240 VAC voltage that can be connected to the breaker box at the utility entrance of the house.  The inverter matches the phase and voltage to that coming from the utility so it is just adding or displacing current that the utility normally provides.  If the home owner is using more current than the solar panels can provide, then some still comes from the utility.  If he uses less than the panels can provide, then some of the current can be sold back to the utility and this makes his electric meter spin backwards.  If the utility loses power, the invert must disconnect its AC output to protect linemen trying to restore power from electrical shock.
     Below, the AC power goes through the AC disconnect (bottom left) which allows the utility power to be disconnected from the inverter.  Then, it goes through the kilowatt hour meter (bottom right) so the owner can monitor the energy produced by his solar panels.  The round, silver cans attached to the boxes are lightning arresters which help protect the equipment from a lightning strikes.  There is one for the DC wiring and one for the AC wiring.



I helped Jim make the final conduit connections and wire up the boxes.  Below is a close up of the AC fuse box.



This is the electric meter box minus the meter.



Here is the inverter box.  The four black squares on the left hold the DC side fuses.  The yellow circle is where the DC disconnect switch is located.

 

This is the AC disconnect box just before it goes into the main breaker panel inside the house.  These are some beefy switches because they have to handle a lot of current.



Here you can see Jim has installed the new meter showing all zero's.



     This is the system all closed up and running.  If you look carefully, you can see it has already generated nearly 0.5 kWhr of electricity.  The AC side should be able to put out just under 3kW under normal operating conditions.  With the air conditioner switched off we could see the utility meter spinning backwards.  That was so cool!    One more solar energy convert to who is now reducing his energy bill and cutting his carbon footprint.

 

 Shawn couldn't make it back for the system start-up, but here is the Saturday crew (clockwise), Myself, Alfia, Jim and Walt.  All that is left is final inspection.

 
 
      It was a lot of hard, hot work, but it was well worth it.  I want to thank Jim for the opportunity to get some practical installation experience.  Walt and Shawn were also very helpful in understanding the panel installation process.  I think I learned a lot by doing it firsthand which wasn't included in my class room training.  Now, my goal is to look for opportunities where I can be the installer on record for two systems so I can complete the final NABCEP solar PV certification process.  I think that would be a feather in my cap in the solar system design/integration workplace.