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Thread: PLug in Wall GTI Vs Central or Micro Inverter for a 4-5KW system

  1. #11
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    I should be more careful about the advice I give to people, I forget not everyone has the background nessessary for a safe installation

  2. #12

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    1). Make sure that your meter is reversible, or you might need extra money for meter.

    2). Do not go to option 3 " plug in GTI", Those GTI are low voltages and work well and high Efficacy with single solar panel, If you use it for high power parallel connection, 1000W solar panels get only 600W pump back to grid while "option 1" and "option 2" get 25% more power back to grid in real life.

    3). If you go with Enphase GTI option2, it is fine. If you go with Option 1 Sunboy4KW, Make sure get good grade of same type/Watts of solar panels, Do not get "Costmetic" discount grade solar panel, you will have less Dollar/Watts in String GTI connection.

    4). "DIY" solar panels look cheap but are they really? 90% of those solar cells are costmetic grade plus hard to do good weather protection, Also Money = Watts x service years, you get less money return for long run.

    - From Money point of view, String inverter option 1 is still the cheapest and easy to install, and buy 1X600W 22-60Vplug in GTI for your 2x135W DIY solar panels in series for maxium power.

    - From safety point of view, If you use 20X230W solar panel, Those are 36 Volts each panel, if you put them together, It will be 720V and too high for your Inverter, So you might consider parallel them in pair, then connect them in string 10X36V = 360V, Make sure read more info before doing it.

  3. #13
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    Quote Originally Posted by computerpc101 View Post
    1). Make sure that your meter is reversible, or you might need extra money for meter.

    2). Do not go to option 3 " plug in GTI", Those GTI are low voltages and work well and high Efficacy with single solar panel, If you use it for high power parallel connection, 1000W solar panels get only 600W pump back to grid while "option 1" and "option 2" get 25% more power back to grid in real life.

    3). If you go with Enphase GTI option2, it is fine. If you go with Option 1 Sunboy4KW, Make sure get good grade of same type/Watts of solar panels, Do not get "Costmetic" discount grade solar panel, you will have less Dollar/Watts in String GTI connection.

    4). "DIY" solar panels look cheap but are they really? 90% of those solar cells are costmetic grade plus hard to do good weather protection, Also Money = Watts x service years, you get less money return for long run.

    - From Money point of view, String inverter option 1 is still the cheapest and easy to install, and buy 1X600W 22-60Vplug in GTI for your 2x135W DIY solar panels in series for maxium power.

    - From safety point of view, If you use 20X230W solar panel, Those are 36 Volts each panel, if you put them together, It will be 720V and too high for your Inverter, So you might consider parallel them in pair, then connect them in string 10X36V = 360V, Make sure read more info before doing it.
    Yes meter is reversible I have checked it on the bench by sending 2x 110v on the outputs and connected a load to the input. Span backwards !!! sooner or later they will change it out but for now its a start by the time they get round to it it will be 5 years.

    I will make 2 strings of Panels to keep voltage down and run to a junction box first then run a #10 (DC wire gauge calc on 360V 15A 20m length 1% loss says min #11) down to inverter about 60ft away.

    House is steel structure with grounding wire and tin roof can I ground panels to that or do I need a separate ground for lightning ? Do Central inverters get effected by Lightning strikes ? if so is there a simple protection ?

    Any advice welcome and thanks to all experts for info so far !

  4. #14
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    When checking a meter just don't see if the wheel spins backwards. There are meters out there that the wheel spinning simply sends an inpulse to the counter and will count up regardless of which way the meter is spinning. Run the test long enough to verify that the meter is counting down.
    Rich
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    NABCEP certified Technical Sales Professional

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    http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)

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  5. #15
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    Quote Originally Posted by voodoocr View Post
    House is steel structure with grounding wire and tin roof can I ground panels to that or do I need a separate ground for lightning ? Do Central inverters get effected by Lightning strikes ? if so is there a simple protection ?
    Simplest/most straightforward solution is a copper wire running to each panel (panels generally have dedicated grounding locations) run back to the structure's primary ground point (rod in the ground, water supply pipe etc.) It is in general a bad idea to rely on incidental contact between panels and racks, racks and metal roof etc.

  6. #16

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    billvon is right, All UL solar panel come with ground connection hole, Just connect them together and ground it to ground, do not ground it to your power line, Ground it to ground directly either "Copper rod" " Metel water pipe", not very much work.

    In My area, Our electricity rate is 6 cents only, I installed 1/3 size of my 5KW system and decided to wait awhile for better timing, It does need cleaning occasionally here due to dust problem unless you install them more vertical.

    I also installed a small testing 400W Wind turbine, It was even worse Idea here because of higher maintenance and noise problem with expensive strong mounting system needed. ( For winter time power)

    They are investment, I find that it looks $100 project but it is easily end up $10,000.

  7. #17
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    Quote Originally Posted by computerpc101 View Post
    billvon is right, All UL solar panel come with ground connection hole, Just connect them together and ground it to ground, do not ground it to your power line, Ground it to ground directly either "Copper rod" " Metel water pipe", not very much work.

    In My area, Our electricity rate is 6 cents only, I installed 1/3 size of my 5KW system and decided to wait awhile for better timing, It does need cleaning occasionally here due to dust problem unless you install them more vertical.

    I also installed a small testing 400W Wind turbine, It was even worse Idea here because of higher maintenance and noise problem with expensive strong mounting system needed. ( For winter time power)

    They are investment, I find that it looks $100 project but it is easily end up $10,000.
    Ok thanks for the info I think the quote I got includes grounding lugs at least and I do have a copper pole in the ground which is attached to my structure I will run a separate copper line down to ground.

    I have looked at sizing the system up to 7KW from what I read 80% can be accounted for waste by the time you finish so 30x 230w panels might be a better bet with a SB7000US looking at an electricity consumption of about 10K Kwh per year minimum with some days as much as 80kwh consumed with AC units running and stuff.

    My estimates of $16K investment (Including shipping and tax from Miami to costa rica ) with $3K a year bill (yes here we are being charged a nice 30C/kwh) is that grid parity would be reached in 5 years. I will be doing the install myself with a qualified US electrician at hand.

    Now waiting for panels to come in from Germany to Miami.

  8. #18
    alta780
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    Quote Originally Posted by voodoocr View Post
    Ok thanks for the info I think the quote I got includes grounding lugs at least and I do have a copper pole in the ground which is attached to my structure I will run a separate copper line down to ground.

    I have looked at sizing the system up to 7KW from what I read 80% can be accounted for waste by the time you finish so 30x 230w panels might be a better bet with a SB7000US looking at an electricity consumption of about 10K Kwh per year minimum with some days as much as 80kwh consumed with AC units running and stuff.

    My estimates of $16K investment (Including shipping and tax from Miami to costa rica ) with $3K a year bill (yes here we are being charged a nice 30C/kwh) is that grid parity would be reached in 5 years. I will be doing the install myself with a qualified US electrician at hand.

    Now waiting for panels to come in from Germany to Miami.
    What make of panels are you buying at $1.25 per watt, including shipping from Germany to Costa Rica?

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