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Thread: PV System for My Own House

  1. #11
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    Quote Originally Posted by electrofelon View Post
    Not sure which the OP was planning, or if he has room for a ground mount, but I would go ground mount if possible. Probably will be able to get more ideal angles and better production than the roof, unless the roof gets you above obstructions. Also one can "homebrew" ground mount mounting structures (assuming you want to invest some time to save some money) much easier than roof mount systems. Lastly, if you need another structure anyway, like a carpart or wood shed, it can make it really cost effective.
    Ground mounting is generally more expensive than roof mounting. You might be able to "homebrew" a ground mounting system but you might not, depending on where you are. Some AHJs require a PE stamped structural drawing or letter for a ground mounted PV system.

    One advantage, however, to a ground mounted system is that in general rapid shutdown rules do not apply.

  2. #12
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    New York, 40.7514,-73.9925
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    I am not a PV expert, but I'll tell you what I did at my house.

    I did a 200A main with a 50A branch breaker in position 1,3 with a mechanical slide interlock (Reliance). The only thing I would do different would be to add extra space for watt meters.

    Then a line side tap service fused disconnect for PV supply. I only had enough South facing roof for 8kW of panels and a 6kW inverter (actually it has (2) 3kW circuits for better max power point tracking). I live in the Northeast, so I only make 6kW on few and far between periods.

    That way I have the ability to use a gen and PV at my choice (not at the same time).

    Because of my utility pays me the same $$$ as it costs me to buy kWh from them, the battery is not cost effective for me, so I don't worry about it
    Ron

  3. #13
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    Feb 2003
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    San Jose, CA
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    Hey…….Sorry for the delay in responding. I have been on the forum some for only enough time to quickly read a few topics.

    First, I want to thank all that replied.

    It sounds like I’m fine going with the Panasonic panels if they are the most economic for me to get over the LG’s.

    As far as installing a Tesla or other battery. This is just a possible future option. It’s definitely not mandatory and probably will not happen in the near future if ever. I just want the service equipment to support adding it.

    I’m mounting my 200 amp meter main and 400 amp panelboard about 3’ apart. I will nun a raceway from the meter main down, over that up to the panelboard. Since the 400 amp panel board has quite a bit of space for only 200 amp conductors my though is if I ever add a gateway I could mount it next to the panel then extend the line/load conductors into the panel. My other option is I could easily add a gutter under the panel later.

    One poster suggested using a 200 amp service panel that has 225 amp bussing. This is actually how most of our combination service entrance equipment is built now. This would be fine if just adding the 10K of PV but not if adding a battery or batteries.

    This system is a rooftop not a ground mount. I have 1 good large area of roof so we filled it up as much as possible. That worked out to 30 panels. Its 3 rows of panels between the ridge and eve. Should make installation easy.
    Curt Swartz
    Electrical Contractor

  4. #14
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    Quote Originally Posted by curt swartz View Post
    ...

    One poster suggested using a 200 amp service panel that has 225 amp bussing. This is actually how most of our combination service entrance equipment is built now. This would be fine if just adding the 10K of PV but not if adding a battery or batteries.

    ...
    It would be fine for one Powerwall unit (30A breaker) and a 40A solar breaker (7600W inverter, not atypical for a 10kW DC system). However it would leave you no room for additional Powerwall units, or any other AC-coupled storage solution requiring more than a 30A circuit.

  5. #15
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    Quote Originally Posted by jaggedben View Post
    ... a 40A solar breaker (7600W inverter, not atypical for a 10kW DC system)...
    That would be a 1.32 DC:AC ratio, which is more than I use for any systems I design. Some AHJ's I deal with dictate a 1.20 max ratio to qualify for incentives.

  6. #16
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    Quote Originally Posted by ggunn View Post
    That would be a 1.32 DC:AC ratio, which is more than I use for any systems I design. Some AHJ's I deal with dictate a 1.20 max ratio to qualify for incentives.
    I have pushed ratios that high when the cost of a service upgrade isn't justified by the extra energy gained with a higher-power inverter. Also some systems with panels facing different directions never get above the inverter nameplate, even at that ratio. When both factors are present it's kindof a no-brainer. I have learned to explain it clearly to the customer though.

  7. #17
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    Quote Originally Posted by jaggedben View Post
    I have pushed ratios that high when the cost of a service upgrade isn't justified by the extra energy gained with a higher-power inverter. Also some systems with panels facing different directions never get above the inverter nameplate, even at that ratio. When both factors are present it's kindof a no-brainer. I have learned to explain it clearly to the customer though.
    Still, I wouldn't call 10kW DC STC on a 7.6kW inverter "typical", although the optimal inverter "overloading" can be an elusive number. What software are you using to determine the maximum output of a module at a specific location and orientation?

  8. #18
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    Quote Originally Posted by ggunn View Post
    Still, I wouldn't call 10kW DC STC on a 7.6kW inverter "typical", although the optimal inverter "overloading" can be an elusive number. What software are you using to determine the maximum output of a module at a specific location and orientation?
    I said 'not atypical'. Maybe 'not unheard of' would have been a better choice of words.

    I use SolarEdge's software for determining how much is lost to clipping on such systems. I haven't done that kind of overpowering in other cases (except microinverters where a higher power inverter wasn't available).

  9. #19
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    I have another question. My supplier sent me a material quote for all material. It includes the standard SolarEdge inverter not the newer Wave unit. I don't know if this is what they stock or if it has to do with pricing. Is the Wave better or worse than the older model?

    They also included a Zigbee module but I don't believe I need that if I have an Ethernet connection correct?
    Curt Swartz
    Electrical Contractor

  10. #20
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    May 2011
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    The HD Wave is smaller and lighter, which is great for us guys installing them everyday but maybe not as important to the owner if space is not an issue. They are in my experience a little bit less reliable. They also limit power output to actual nameplate, wheresas the older ones will go a few percent over if voltage is above nominal. However they are also 99% efficient instead of 98.

    If you're getting a 10kW inverter, the HD wave version just came out. I wouldn't be surprised if your supplier still has some older stock they'd like to ship. The lower power versions came out last year.

    You don't need the Zigbee if you can bring a physical ethernet hookup to tue inverter.

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