Learning Some Lessons

etcm

Well my system is constructed and I am awaiting inspection and interconnection with the local utility. Deciding to check out my self-designed/installed system, I placed it in service - only to discover it produced about 1.2 kWH at a 0.2 kW rate the first day as it only charged the battery. The only setting on the Outback Mate 3 that I did not change was the Generator setting, the Radian inverter would not send power into a generator. No generator attached, but the setting said it. The Outback technical assistance walked me through the firmware updating for the Mate3 and the Radian inverter and then placing the unit in operation. The two FM80 CC's each had a different firmware version, but the tech assistant said that can only be changed at the company. The first 1/2 day it produced 20.5 kWH the next day, partially sunny, it produced 37.6 kWH. What I found interesting was that each of the two 3.05 kW arrays(STC rating) had 3.5kW peaks. The temp was about 55F. Then, during the weekend, I saw the sun break out while I was observing the power meter...and the meter pick up (increased) the count rate. Seems the meter reads power flow...in either direction! So that was enough for me to shut down except when we are cooking, etc. or during low power production in the evening. It is quite a thing to see the house in operation and the power meter not clicking at all!
I still have a basement to finish and installation of the basement sub panel that will receive the inverter power if/when the grid goes down.
My panels are all at the same angle on the same roof exposure and the CC's are very close to each other in output...but in different ways. One operates with a higher input voltage/lower amps (closer to the data sheet MPP point) and the other has a voltage lower than the MPP point and has higher current ...and about a 1-3% higher power output.
The input voltages vary over a large range 62-72 at varying times, we've had a lot of clouds and rain lately (Indianapolis) and this rig is still producing at a 1.2-2.5 kW rate, even with the clouds! This project took a long time but I am very pleased.
I did have a local installer mount the rails/hardware and panels on the roof. As I was crawling up on my shaking ladder my wife drew the line, I relented.
When I rewired the Outback GSLC175PV120/240 load center, it knocked me off track for a lot longer than I thought. My 2AWG and 4AWG wires broke my GFCI breaker tabs, and manipulating my large gauge replacement wires in the panel was difficult. I cut and re-lugged the wires. That $25 pairs of wire cutters was sure a lot easier/nicer than the hacksaw I used when starting the project. One of those moments where you think, "What was I thinking?!" - by using a hacksaw to cut the cables.
I tried to run two 2AWG USE2 wires and a single 8AWG (THHN) ground wire inside a 1-inch PVC conduit-from my roof eave, underground and to my outside DC disconnects. The wires got stuck, I broke the pull ROPE, and had to dig up the 20-inch deep conduit to extract it! Note- I had used a lot of slime electrical wire lubricant from both sides After digging it up, I replaced the 2 one-inch conduits with a single 2-inch conduit that carried the wires from both arrays out of teh combiner panel. The wires/cables slid right in and through the conduit. Oh yes, when rewiring a panel, make sure you do not cut the 3-4 feet of 2AWG cable that leaves you 2 feet short on a 55 foot run That kind of execution just runs the costs up even more. Thanks for letting me rant a little.
I feel like I've accomplished some...now if only the federal gov't will have enough $$$ to fund the tax credit I should be getting.:D

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20x305W Helios 7T2 panels(6.1kW), Outback Radian Inverter&GSLC175PV120/240 panel, FlexMax80 x 2, 178AH @48VDC

inetdog

Re: Learning Some Lessons

etcm wrote: »

I replaced the 2 one-inch conduits with a single 2-inch conduit that carried the wires from both arrays out of teh combiner panel. The wires/cables slid right in and through the conduit.

Yes, two 1" pipes and one 2" pipe both have about the same amount of plastic in them, but the 2" has twice the wire area inside compared to both 1" together.
And that is not even taking into account that it is easier to get around bends.