Me the mega newbie - please advise!

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spydox
spydox Registered Users Posts: 4
in Solar Beginners Corner #1
Hello, I'm a EE with a strong desire to design and install my own PV solar supplemental system in FL. Although I know a lot about electrical systems, power, etc, (1) I know almost nothing about residential solar systems, and (2) after hours of studying websites looking for information, I'm only MORE confused.

It seems most of the websites are trying to sell me,and install, a very expensive solar system with a dubious payback in my lifetime.

My goal is to start out with a small prototype, perhaps 1KW @220vac, that I can use to demonstrate some capability and perhaps some small savings from pure-grid electric. I'd like the system to be expandable, but I have many questions about that.

1.) Is there grid-tie technology (panel(s) to GT Inverter to 220VAC outlet) battery-free, reliable, and safe?

2.) Are proven kits available at a reasonable cost, or would it be better (more economical) to piece one together? For example, I see 500w GT Inverters on, say, Amazon for $199, and 500w panels for around $500 or less. So is it reasonable to think that I can put together a demonstrator 500w system for under $1000?

3.) Say I start with 500w or 1kw and I like the results, and want to step up to say 5kw. Can I just ADD another 4KW system and plug it into ANOTHER 220VAC outlet? The EE in me says that with phase and other errors, perhaps doubling or adding parallel systems could have diminishing returns, and perhaps introduce some potentially significant sinusoidal distortions.

Anyhow if there is a good starting point for someone who has like $1000 to work with, and wants to get a demo system in place I'm all ears!

Thank-You.8)
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  • peakbagger
    peakbagger Solar Expert Posts: 341 ✭✭✭
    #2
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    Re: Me the mega newbie - please advise!

    You cant legally backfeed a 220 volt outlet in the US. Generally the utility will require a rated grid tie inverter tied into your panel. The inverters sold on Amazon are most likely none UL rated units that cant legally be used in the US, you can buy them but you are liable for using them, I.E. someone gets zapped and it coming out of your pocket not the insurance company. As an EE this is dumb thing to do especially if you have a PE.

    You can probably do a demo system with Enphase or equivalent microinverters, they are code legal and are sized one inverter for one panel. Within the limitations of your electrical panel backfeed rating, you can expand modularly by adding more panels with no issues. The trade off is that you pay more per watt for the microinverters. Soem folks argue they wont last as long as convetional inverter as they are located in a harsh environment but to date I havent heard of a lot of failures. Do note you need a net metering agreement with your utility and they may require other equipment. In case you want some subsidies you may want to check out this website http://www.dsireusa.org/ and remember you an get a 30% tax credit for solar electric installations.
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  • spydox
    spydox Registered Users Posts: 4
    #3
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    Re: Me the mega newbie - please advise!

    Thank-You sir, this is exactly the kind of advice I was seeking. And your 100% correct- I don't wish to violate any codes or regulations from any agency, and I want to ensure EVERYONE is safe

    I wonder- what RATING should I look for to ensure conformance? I see CE-5 and other terms tossed around, all of which I'm unfamilair with.

    I have seen this term *micro-inverter* on many sites- according to wiki it means ONE inverter, per-panel. That has appeal since as you suggest, I can readily get a matched pair, code-conformal.

    I will call my utility today to see what I can discover about the agreement you mention.

    S
    peakbagger wrote: »
    You cant legally backfeed a 220 volt outlet in the US. Generally the utility will require a rated grid tie inverter tied into your panel. The inverters sold on Amazon are most likely none UL rated units that cant legally be used in the US, you can buy them but you are liable for using them, I.E. someone gets zapped and it coming out of your pocket not the insurance company. As an EE this is dumb thing to do especially if you have a PE.

    You can probably do a demo system with Enphase or equivalent microinverters, they are code legal and are sized one inverter for one panel. Within the limitations of your electrical panel backfeed rating, you can expand modularly by adding more panels with no issues. The trade off is that you pay more per watt for the microinverters. Soem folks argue they wont last as long as convetional inverter as they are located in a harsh environment but to date I havent heard of a lot of failures. Do note you need a net metering agreement with your utility and they may require other equipment. In case you want some subsidies you may want to check out this website http://www.dsireusa.org/ and remember you an get a 30% tax credit for solar electric installations.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #4
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    Re: Me the mega newbie - please advise!

    Generally in the US you need to pull a permit (usually requires line drawings and site location) and get an interconnect agreement for the utility, it is their grid and they will need to have the proper meter in place. Good quality grid tie setups can be had for about $4.25 a watt installed, you can save a pretty good chunk of that by doing the work yourself. Usually the larger you go the better the price per watt. Enphase will cost slightly more than conventional central inverter designs. Some panel bargains are around, recently there was a large group of Evergreen panels out of their bankruptcy for $0.78 a watt + shipping.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #5
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    Re: Me the mega newbie - please advise!

    Grid Tied Inverters are pretty close to a 1.0 Power Factor (0.95 PF is considered "pure/true" sine wave inverter).

    Are you after saving money on your power costs or want emergency/backup power if the grid goes down. A "pure" Grid Tied system (solar panels + GT inverter) does not supply any power if the grid is down. You need an Off Grid or Hybrid Inverter (Hybrid Inverters have a battery bank and can do both GT when the grid is up and switch to off grid mode when the utility power is down).

    GT is the least expensive/most reliable. Off Grid and Hybrid is much more expensive and you have to replace the battery bank every ~5-10 years or so. And, for the electronics (inverter, possible solar battery charger, etc.)--You should plan on buying new electronics every ~10+ years (components fail, many parts/service centers drop support after 10 years).

    From what I have seen, trying to build out a Grid Tied (or off grid) system over time is not very cost effective. For GT--you have to pull permits/utility permission each time you add to the system (I would guess 3kW chunks could be cost effective). And for off grid systems, they are hard to grow by more than 2x without needing to change from 12-24-48 volt battery banks, add new batteries to old banks, and adding new solar panels with different Vmp/Imp ratings to an existing array.

    Off grid systems are not cheap power (~$1-$2+ per kWH vs $0.10 to $0.20 per kWH for most people)--But if you need a few weeks of backup power after a storm--May be worth it (if your power usage is low, a smaller Honda or Yamaha 900-2,400 watt inverter-generator set can get your fuel usage down to 1-4 gallons per day vs the 12-30+ gallons per day for a large 10kW backup genset).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • spydox
    spydox Registered Users Posts: 4
    #6
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    Re: Me the mega newbie - please advise!

    Thank-You Dave and Bill- more very helpful information.. You guys are great on this forum- even though Im a newbie the veterans make me feel welcome (unlike many other forms I've seen!).. I'm studying each reply in detail.

    I just spoke to FPL, and, understandably, they only allow a licensed contractor to work with them to install a system. That's a kink I hadn't anticipated so I gotta figure where to go from here. He suggested I might be able to get my own license.




    BB. wrote: »
    Grid Tied Inverters are pretty close to a 1.0 Power Factor (0.95 PF is considered "pure/true" sine wave inverter).

    Are you after saving money on your power costs or want emergency/backup power if the grid goes down. A "pure" Grid Tied system (solar panels + GT inverter) does not supply any power if the grid is down. You need an Off Grid or Hybrid Inverter (Hybrid Inverters have a battery bank and can do both GT when the grid is up and switch to off grid mode when the utility power is down).

    GT is the least expensive/most reliable. Off Grid and Hybrid is much more expensive and you have to replace the battery bank every ~5-10 years or so. And, for the electronics (inverter, possible solar battery charger, etc.)--You should plan on buying new electronics every ~10+ years (components fail, many parts/service centers drop support after 10 years).

    From what I have seen, trying to build out a Grid Tied (or off grid) system over time is not very cost effective. For GT--you have to pull permits/utility permission each time you add to the system (I would guess 3kW chunks could be cost effective). And for off grid systems, they are hard to grow by more than 2x without needing to change from 12-24-48 volt battery banks, add new batteries to old banks, and adding new solar panels with different Vmp/Imp ratings to an existing array.

    Off grid systems are not cheap power (~$1-$2+ per kWH vs $0.10 to $0.20 per kWH for most people)--But if you need a few weeks of backup power after a storm--May be worth it (if your power usage is low, a smaller Honda or Yamaha 900-2,400 watt inverter-generator set can get your fuel usage down to 1-4 gallons per day vs the 12-30+ gallons per day for a large 10kW backup genset).

    -Bill
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  • spydox
    spydox Registered Users Posts: 4
    #7
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    Re: Me the mega newbie - please advise!

    Although here in FLA it would be nice to have backup power, the simplicity and low maintenance of the GT Inverter system is appealing. And we've weathered enough hurricanes now that we're pretty quick getting the generator running and connected.

    THanks!
    BB. wrote: »
    Grid Tied Inverters are pretty close to a 1.0 Power Factor (0.95 PF is considered "pure/true" sine wave inverter).

    Are you after saving money on your power costs or want emergency/backup power if the grid goes down. A "pure" Grid Tied system (solar panels + GT inverter) does not supply any power if the grid is down. You need an Off Grid or Hybrid Inverter (Hybrid Inverters have a battery bank and can do both GT when the grid is up and switch to off grid mode when the utility power is down).




    -Bill
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
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    Re: Me the mega newbie - please advise!

    For the best bang for the buck, go grid tie, and then buy a stand by genny for those rare, prolonged outages.

    Tony
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #9
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    Re: Me the mega newbie - please advise!
    spydox wrote: »
    Thank-You Dave and Bill- more very helpful information.. You guys are great on this forum- even though Im a newbie the veterans make me feel welcome (unlike many other forms I've seen!).. I'm studying each reply in detail.

    I just spoke to FPL, and, understandably, they only allow a licensed contractor to work with them to install a system. That's a kink I hadn't anticipated so I gotta figure where to go from here. He suggested I might be able to get my own license.

    Sometimes a few queries,to the local installers will get you an agreement with them to do the grunt work, mounting panels, running conduit ... that can be a substainal saving on a install, they pull the permit, wire it and deal with the utility.
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