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home > solar power
Installing a grid intertied
solar electric power system

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Overview System
Financing Panel
Hardware Grounding Rail

11 Enphase M190 inverted mounted to IronRidge  Genesys rails
August 14, 2009
I decided
not to wait for the remaining inverters and start by installing the 12 (of 21) that I have so far.  These are the brand new Enphase M190 units (now discontinued) that were in high demand and short supply.  This installation is not going the way that I visualized it -- I had pictured a barn raising with half a dozen friends taking a day or so and we'd have the whole thing done.  Instead I'm doing it piecemeal while I wait for the inverters to arrive.
Enphase M190 cable too short to reachI began at the bottom right and wired the cable end into the junction box and then mounted the first inverter at the bottom right of the roof.  I had planned to run the AC circuit up 3, left 1, down 3, and on to the left for 15 units. 

Each inverter's 240 Volt AC cable plugs into the next unit like extension cords in series.  The maximum number of inverters per group is limited by the 15 Amp circuit breaker, in this case my limit is 16 units and I'm installing 15 in the first group, and the remaining 6 in a second group.  Eventually I will add to the 2nd group as finances allow.  But when I installed the second inverter above the first I found that the AC cable built into the unit was not long enough! 

So I called Enphase tech support and spoke with Eric.  I asked him to look at my blog so he could see my layout and understand the issue.  He immediately offered to send me some 6ft. extension cables for free!  So I asked for 4 of them.  If I change the wiring sequence to start at bottom right, go left 5, then up 1, then right 5, then up 1 then left 5 -- then I only need to go up twice per group of inverters.  The second group will have 6 inverters to begin with and eventually 14 total as I can afford to add to the system.

The previous model M175 had AC cables with male and female ends, the M190 has a male cable and a female connector built into the unit.  I think the 2 cable design was better as it allowed more flexibility in installation.

Sept. 9, 2009.  An Enphase staffer told me today that the cables have been extended 8" on all production units
Here is a system wiring diagram:
System wiring diagram
Enphase M190 inverter mountingI am mounting the inverters with an extra large washer, regular washer, lock washer and nut over the right mounting slot.  The large washer is there to cover the WEEB grounding washer to ensure it gets good even pressure on it.  I used a torque wrench to tighten the nuts per the Wiley Electronics recommendations. 

Since I did not originally have a torque wrench, I looked for an inexpensive one on the web and found one for about $15.00 at Harbor Freight ToolsTorque wrench
While they are known for cheap tools that are often not much good, this tool has worked out fine on the job.  I have found many great bargains at Harbor Freight.

Update April 14, 2010
Enphase has released an app note clarifying how to use the WEEB grounding system for their inverters.  Download it here.

September 3, 2009
roof showing panels and 9 mor inverters
I finally got the last 9 inverters.  I had to scour the web to find a supplier that had some in stock - they are selling out fast.  So I went up on the roof and installed them today in preparation for installing the remaining panels tomorrow.

Enphase M190 inverter and mounting rail hardware - shwing WEEB washerEnphase M190 inverter and mounting hardware - showing WEEB washer under stainless washers and nutHere are some images that show the WEEB grounding washer that I put beneath the Enphase inverter bracket to ground it to the Genesys mounting rail.
Torquing down Enphase M190 inverter mountConnecting Enphase M190 invertersHere I am torquing down the inverter mounts and plugging the inverter in to the extension cable that goes down to the next row.  It's a "plug-n-play" system! (Note that I had turned off the circuit breaker before working on the roof!)

Thanks to my wife, Rebekah Younger for these photos
Junction box wiringThe daisy chain wiring of the inverters terminates to a cable that comes from a weatherproof junction box.  I used a larger than necessary box to have plenty of room inside - could have used a smaller 4X4 box in retrospect, but they are cheap.  Note the weatherproof wire connection on the side of the box.
Tomorrow, we'll install the solar panels to complete the 21 panel array.

Here are 2 really good videos that detail the installation of a system in New Jersey.  Very clear and detailed:
Part 1 New Jersey PV Solar Installation of a Enphase Energy Micro Inverter system
Part 2 New Jersey 5.6 KW PV Solar Installation of a Enphase Micro Inverter system

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