Foundation and Inverter PDF

The hole needed to be about 5' deep by 3' square.  Thankfully our dirt isn't too rocky, so the digging wasn't that bad. 


Digging the hole



Rebar Cage


I welded the rebar cage all together since that seemed like the best way to keep everything in alignment and it's really easier than trying to wire it together anyways. It's very rigid like this, which really helps keep all the bolts aligned just right.

Rebar Cage


The J-bolts are welded to the rebar, and we made the 2x4 jigs to hang it at the correct height.  It's only about 1.6 yards of concrete, so we mixed it in a small mixer and dumped it in.



And here's a shot of it almost full.  We finished the top and then let it cure a little over a week before putting anything on it.

Line Trench


The trench full of conduits.  There's one to bring the DC power from the panels into the inverter, and one to bring 120 VAC out to run the tracking motors and such.  The 3rd one has a piece of coax (that Neal so kindly donated) in it to use for a camera.  It's about a 150ft run, but the PV system runs at about 300 VDC so the losses are pretty negligible (on the order of 20 watts worst case). 


Conduit Terminations


It all terminates at the side of the house.  The inverter is mounted in the basement, so we were able to put the conduit straight throught the wall and into the inverter junction box.


Inverter Mounted


Here's the inverter mounted.  This is the Xantrex GT2.8 and so far it's worked very well.


Meter and Disconnect


This is the meter and AC disconnect switch.  Although our utility allows net metering, they want a second meter to measure just what the PV system is generating.  They then replace the main meter with a bi-directional unit that keeps track of how much has been used versus how much has been pushed back into the grid.  The inverter outputs 240 VAC and is connected to that square D external disconnect.  This in turn is connected to the generation meter which is itself wired into the breaker panel.  It's connected in the panel like any other 240 V circuit.  Next is raising the tracker and mounting all the panels.