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Thread: Grid Tie Micro Inverter that plugs into house AC outlet...

  1. #1
    Luposian Guest

    Question Grid Tie Micro Inverter that plugs into house AC outlet...

    There are a couple of these for $200+. You hook up the red (+) and black (-) wires of your 12v solar panel to it and then plug it (the inverter) into any house AC outlet. And, supposedly, when the sun is shining, you're offsetting your electrical usage! That simple!

    My big question is: Can you set this thing up without having any permits or paying the city any fees for such a setup? In other words, can you (legally) start reducing your electric bill, without anyone knowing about it?

    A neighbor down the street has a massive solar array in her back yard and showed me her electric bill. Her bill wasn't much smaller than ours... maybe $20-$30 less. But I noticed that SSEVC (that's who we have, here in Sierra Vista, AZ) is CHARGING her for net metering! She pays a fee to be generating electricity and yet only got a $20 credit on one of her bills! Her panel array is huge (at least 14' square (if not bigger), I'd guess)... I know it generates more than $20 of electricity in a month! It HAS to, doesn't it?

    Well, anyhow, that's my reason for asking... if I can offset my electric bill by even 150w (that's just where I'd start at), while the sun is shining, it's a great deal to me. But... if the city (and/or the electric company) has to have their cut of the action (no matter how you're doing it), it totally takes away the incentive for doing it at all!

  2. #2

    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    I don't think it is legal. I know it is dangerous,possibly deadly if there should be a power outage and someone was working on the system, and should not be done. It wouldnt make too much of a difference in your bill because you wouldn't be supplying any power except to loads that were running at your house during the day. Any excess power generated would be lost.

    Others will chime in with better answers.

  3. #3
    Join Date
    Jul 2010
    Location
    Maryland Heights, MO
    Posts
    153

    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    Quote Originally Posted by Luposian View Post
    There are a couple of these for $200+. You hook up the red (+) and black (-) wires of your 12v solar panel to it and then plug it (the inverter) into any house AC outlet. And, supposedly, when the sun is shining, you're offsetting your electrical usage!

    Can you set this thing up without having any permits or paying the city any fees for such a setup? In other words, can you (legally) start reducing your electric bill, without anyone knowing about it?
    There is a detailed debate as to the merits and technical challenges
    of one particular such device at:

    http://forum.solar-electric.com/showthread.php?t=8977

    The company listed in that thread, Clarian, at the time was targeting
    early 2011 to release a product. A visit to their website shows no
    updates since initial marketing splash in 2010. I would assume that
    that delay attests to the difficulty of getting UL approval and some
    kind of generic approval to plug into the grid without utilities' consent.

    Quote Originally Posted by Luposian View Post
    A neighbor down the street has a massive solar array in her back yard and showed me her electric bill. Her bill wasn't much smaller than ours... maybe $20-$30 less. But I noticed that SSEVC (that's who we have, here in Sierra Vista, AZ) is CHARGING her for net metering! She pays a fee to be generating electricity and yet only got a $20 credit on one of her bills! Her panel array is huge (at least 14' square (if not bigger), I'd guess)... I know it generates more than $20 of electricity in a month! It HAS to, doesn't it?
    Several things...

    1. A 14' x 14' array would be about 12 PV panels, or on the order
    of 2.7 kw. Such an array would generate something like $400
    worth of electricity per year, or roughly $35/month. It is believeable
    that after deducting any SSEVC service fee, that her array would
    yield only a $20-30/month credit...especially if it were a winter month
    bill that she showed you. During winter, my PV array produces half
    as much as it produces in summer.
    2. It is also possible that her PV array is not producing as much as
    theoretically possible. She might have shading issues, or perhaps
    her array is not perfectly south facing. Either of the latter two
    issues can reduce harvest by 10-20%.
    3. Your house and her house may have entirely different power
    consumption. That means that her bill being "only" $20 less
    than yours may be out of context. For example, prior to my PV
    array's installation, my next door neighbor's bill was double my
    own, even though we are in like houses. This was because I did
    a lot of conservation measures and he has done none. You
    should ask to see her bills before she installed the PV array, for
    true apples to apples.
    4. Lastly, there are monetary incentives other than the monthly
    savings that you may not be aware of. These could include
    the Federal tax credit, a cash rebate from the local utility, and
    cash generated from sales of solar renewable energy credits
    (SRECs). In my own case, such sources represent 30X the
    value of my annual power production.

    John

  4. #4
    Join Date
    Jul 2007
    Location
    Quetico, Ontario
    Posts
    5,025

    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    I've never seen a legal, UL/CSA listed plug in the outlet inverter system. There is a reason that you wish to have the utility and the permit authority involved in grid tie PV. That is to ensure the safety of you, your house as well as the the utility.

    Icarus.

    PS if you are trying to save the dollars equivalent to ~ 150 watt, maybe $.01 per hour for may be 6 hours,, or $.06 per day I would surely bet that I could find 150 watts of energy savings that would save more than $.06 per day. Water heater blanket, heat traps on water heaters, turn off a light or two, change a few more bulbs to LED/CFL, turn down the heating t-stat 1 degree F, or turn up the A/C t-stat the same 1f, water saving shower heads, air dry you dishes, wash your laundry in warm or cold water, air dry your laundry,, and on and on and on.

    Your 150 watts of PV might cost ~$500 installed with an inverter. What would it cost to do some if not all of the above? Nearly nothing.

    T
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

  5. #5
    Join Date
    Dec 2010
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    I can see Mexico from my back yard
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    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    Quote Originally Posted by Luposian View Post
    A neighbor down the street has a massive solar array in her back yard and showed me her electric bill. Her bill wasn't much smaller than ours... maybe $20-$30 less. But I noticed that SSEVC (that's who we have, here in Sierra Vista, AZ) is CHARGING her for net metering! She pays a fee to be generating electricity and yet only got a $20 credit on one of her bills! Her panel array is huge (at least 14' square (if not bigger), I'd guess)... I know it generates more than $20 of electricity in a month! It HAS to, doesn't it?
    There are several things to consider here: Perhaps her bill is only a little lower than yours because she uses a LOT more electricity than you do (I don't know this, it's just a possibility.
    As they say the first step in going solar is to reduce your power consumption, many people just don't get that.

    There are some things you still have to pay for even with net metering. You still have to pay the fee for the meter and you still have to pay the Taxes and surcharges for energy used at night, even if it's energy you banked during the day. A couple of these fees (REST for example) while based on a percentage of energy use are capped at a low level, my REST fee dropped from $3.49 (capped) to about $3 winter & $2.25 summer when I installed my array.
    So basically there are about $20-$25 worth of fees you have to pay even if you generate all of your own power

    The SSVEC Net metering fee is only $2.70, not a lot of money considering how much time and money they have spent reprogramming their billing system to allow net metering. They have only been doing Net metering for a little over a year and don't have many net metering customers. However, it looks like they have worked most of the bugs out now.

    I live out in Hereford and my 3.45kw array mounted on trackers produces more power than I use right now.
    At this time of year I only use about 490-500 kwh a month and my array produces about 700 kwh a month (this time of year). Since September the only month I used more than I produced was December and that was only 4kwh extra. With net metering I just pulled that out of the 600 kwh I had banked.

    Now there are a couple ways you can zero out your bill. You can install an array that is up to 25% larger than you need. On an annual basis, if you push more kwh to the grid that you pull, SSVEC will pay you about 4 cents per kwh for the surplus. The rising costs of diesel will drive up the delivered costs of coal soon and since all of our power is produced by a coal burning power plant up in Tucson, that means they will start tacking the "Whole Sale Cost Adjustment" onto our bills soon. A couple years ago that cost adjuster made up almost 50% of my bill. If you produce more power than you use when the "Whole Sale Cost Adjustment" is in effect, you get a CREDIT for that instead of a charge.

    Finally if you want to install solar, SSVEC currently has about a 4 to 5 year waiting list for the 50% rebate. However they also offer another program that not many people know about or are taking advantage of called a "Performance Based Incentive" that can pay back up to 60% of your costs, the PBI is available NOW, no waiting and PBI customers get paid FIRST, the 50% rebates are only available if the money hasn't been spent on PBI.

    The problem is that the PBI pays back monthly in small amounts over 10-20 years depending on which program you chose.
    I chose the 15 year program so I earn 18.7 cents per kwh that my array produces produce. It doesn't matter whether I used this power immediately or export it to the grid, I get paid for every kwh produced. They have to install a second meter just to measure your arrays output and originally they were saying that they would have to charge for the second meter, but I was only charged once on the month they installed it.
    My PBI payment is about $130 a month, they automatically subtract any fees I owe (basic meter fee, net metering fee, taxes and tarrifs, etc.) and if there is at least $100 left over they cut me a check. Otherwise they bank it and wait until the next month.
    I haven't paid an electric bill since my array went only and most months I get a $100 check, or every two months get a $180-$190 check.

  6. #6
    Join Date
    Apr 2010
    Location
    Near Phoenix
    Posts
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    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    Quote Originally Posted by Luposian View Post

    A neighbor down the street has a massive solar array in her back yard and showed me her electric bill. Her bill wasn't much smaller than ours... maybe $20-$30 less. But I noticed that SSEVC (that's who we have, here in Sierra Vista, AZ) is CHARGING her for net metering! She pays a fee to be generating electricity and yet only got a $20 credit on one of her bills! Her panel array is huge (at least 14' square (if not bigger), I'd guess)... I know it generates more than $20 of electricity in a month! It HAS to, doesn't it?
    See attached for massive!

    Really the right way to go about an incremental add system is to pull the permits, wire the system for final sizing, use micro inverters and talk to the code guys about what they will require to add to that system. None of that is cheap, the code guys may require a new permit at every add of panels/inverters and that is an additional expense you will have to deal with.

    One of the problems with "plug-in" inverters is that they can over load the line they are attached to. Just think of it this way, 15 amp breaker can pass in 15 amps on a 14 gauge wire to the circuit, then you add a plug in inverter to the line say another 15 amps, now you have the potential to load a 14 gauge wire rated for 15 amps up to 30 amps with out a breaker trip. Surely that is a potential fire from an over heated 14 gauge wire. If a fire did happen, your insurance company could deny your claim because of your actions.
    Attached Images Attached Images  
    My TED 5000 system
    Sticking it to the power company one watt at a time!
    60 Ningbo Electric 175 watt panels and 12 Canadian Solar 180 watt panels with 2 PVP 5200 Inverters

  7. #7
    Join Date
    Feb 2011
    Location
    on a ranch, NM
    Posts
    124

    Default Re: Grid Tie Micro Inverter that plugs into house AC outlet...

    Those cheap grid tie inverters like to over heat and cut off when you try to run them any where near rated capacity.
    In factory configuration they are only good for about two thirds what they are rated for.
    I have to modify them with a big CPU fan and add some air vents before I can even think about running them any where near capacity.
    50'' diameter 3 bladed 24V 500w PMA powering a modified 14-28v 300w grid tie, too close to the ground. + a lot more toys.

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