Changing system from off grid to grid tied a few questions.

Stix
Stix Solar Expert Posts: 31 ✭✭
in Grid Tie and Grid Interactive Systems #1
  Well after getting my feet wet in a off grid system with a midnight solar controller and 16 250w mono 24v panels 5000w 24v inverter with batteries....(alot of work) I have decided to ditch the batteries and go grid tied.  Looking for ideas on what are the changes/equipment that I would need that would best fit my needs.  I am reading up now on how to tie in a grid tied system and always looking for more information before I change anything.  I jumped into solar fast and learned from alot of mistakes.  

  Trying to avoid them if I can this time.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Grid tied requires a central inverter of a different type (or micro inverters for each panel). Central inverters require different line voltages so you will likely want to rearrange your strings of panels and you may not have a good fit for, likely 2 strings of panels. Check out some of the requirements of different inverters.

    You will also want to go to and ask your power company what they require, most will want an electrician to sign off on your setup and they will likely have an addition person come out and check your system. Some electric companies won't allow grid tie systems (mostly these will be municipally held companies)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • cow_rancher
    cow_rancher Solar Expert Posts: 117 ✭✭✭✭
    #3
    They will also probably require a "special" meter, and of course they will charge you an additional "special" price for that meter.

    Rancher
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  • Stix
    Stix Solar Expert Posts: 31 ✭✭
    #4
    Thanks for the information.  First thing I will do is ask the electric company and then do research on inverters.  What is better micro or central inverters?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #5
    If you have an open flat array with no major shading issues... I would personally suggest a Central Inverter.

    If you have shading issues and/or east+west+south facing panels, micro inverters may be better.

    If your building department likes on-roof shutdown, micro inverters may be better.

    You also need to look at your panels (number, Vmp and Imp ratings) and figure out which will work. Micro inverters need specific panel ratings that are sized to the inverter's capabilities. Central inverters, you have to match the inverter's Varray and Iarray requirements (like 8-15 panels in series, 1, 2, 3 series strings) and your local weather conditions (minimum and maximum temperatures).

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