2 PVPowered 3500 Grid Tie Inverters powering my home.

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• BB. Super Moderators, Administrators Posts: 31,330 admin

  December 2018 #2

  You need to have a large enough Main panel to add ~3x 20 amp breakers and not exceed the panel's rating...
  
  For example, 200 amp panel * 1.2 solar allowance = 240 Amp total (main breaker+solar breakers). So, if you want to add 3x 20 amp breakers for 60 amps total, you would need to change the main breaker to ~175 amps which gives you room for 240a-175a=65 amps for solar breakers.
  
  Details matter here... So, you need to look up the rating of your 3,500 Watt GTI inverters and what breaker they need (appear to be 20 amps from quick search).
  
  You also need to check with your utility--They may have a limit for 10,000 Watt GTI system -- Above which may have more regulations (and different pricing plans).
  
  The other possible issue... If you have a long cable run from home to the pole transformer and relatively high AC line voltage (~255 VAC or higher), it is possible that the voltage drop (actually voltage rise) can trip the GTIs (overvoltage trip voltage is generally 260 to 265 VAC).
  
  Each GTI inverter should have all its panels on the "same plane" (don't point some panels SE and others SW, or different tilts). This will reduce output harvest.
  
  Otherwise, following code, good grounding practices (including lightning control, if an issue in your area), GTI systems are as simple and inexpensive way you will find to harvest solar electric energy. There is nothing you need to do other than keep free of tree branches, and weeds (if ground mount). Lightning and hail storms can be a real problem... And reflections from large arrays into nearby homes can also be an issue for those in the other homes.
  
  -Bill

  Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  

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• solar_dave Solar Expert Posts: 2,373 ✭✭✭✭

  December 2018 edited January 2019 #3

  I run 2 PVPowered grid tie inverter on my 12K system. I have a dedicated AC sub panel that joins the 2 outputs for a single run to the main breaker panel. 
  
  You will notice I have an additional slot in the combiner.  Wonder what that might be someday. (Yes I prepared the feed to the main panel with a heavier gauge of wire).

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• Skip Registered Users Posts: 16 ✭✭

  December 2018 edited December 2018 #4

  Thanks for the info Bill, The inverter takes a 20 amp breaker going to the main, I have a .28 acre lot my house sits on in NW Arizona, no shading to worry about, and I will have ground mounts for the panels. 30 ft from the transformer on the  pole to main panel, and my lot is above the rest of the homes around me plus no homes to the south of my yard, just a clear shot to the sun.
  

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• Skip Registered Users Posts: 16 ✭✭

  December 2018 #5

  That's a nice setup Dave, I will add that to my setup, saved your picture to my computer.
  

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• BB. Super Moderators, Administrators Posts: 31,330 admin

  December 2018 #6

  Skip,
  
  Sorry, I misread your first post... You are just looking at 2x 3.5kW GTI systems... The math still holds, just different number(s) of circuits.
  
  The solar GTI breakers are installed in the main panel (or sub-panel feed to main) at the opposite end of the bus bar from the main breaker/utility input connection. For older homes, installing a new sub panel for more breaker/increased capacity is an issue--And increased main breaker capacity can be held up while the utility figures out if your local distribution grid can handle the additions/changes.
  
  Check very closely your rate plans... Today, most utilities are actively working against the present (subsidized) grid tied solar systems (buying and selling power at retail... The utilities want to buy your power at wholesale and resell it back to you at retail).
  
  Besides charging the game near term (or 10 year grandfathering your present system rate plan), they are also doing things like jacking up connection charges from $5-$10 per month (happened to me a couple years ago) to upwards of $48 to $96 in a few places.
  
  -Bill

  Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  

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• Skip Registered Users Posts: 16 ✭✭

  December 2018 #7

  I have a 200 amp main panel and removed my 220 vac from my garage, electric dryer , and electric stove from the panel & replaced both with gas, that saves me 100 amps right off the top. Mohave Electric Co-op is my power company, there pretty light on solar punishment  compared to the rest of the power companies in Arizona. My power usage is in the 5 to 6 kw range so a 7k system won't be a big deal to them. Every building in our area has large AC systems so our grid is built for large power usage. On a 7k system I would get $350.00 from the .05 cents a watt for installed system, and as far as I am concerned they can keep my extra power payback and apply it toward my connection charge $16.00 a month. Thanks for your input Bill.
  

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• solar_dave Solar Expert Posts: 2,373 ✭✭✭✭

  January 2019 edited January 2019 #8

  Yeah that will meet the 2010 APS requirements.  Not too long ago I had all the inverter conduit replaced because the flex connectors literally fell apart from the sun. The panels have been remounted since this photo because of the roof repair on the front of the house (NOT cheap fix the roof first).  After 20 years the underlayment failed and a stretch of valley was improperly flashed causing a rotten spot above the garage.  I went the extra mile and replace 4 panels, 2 from hail damage(?) and 2 from broken connection boxes on the backside.  I also had proper triple flashed standoffs installed.
  
  Here is a couple pictures of the other components.
  
  

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