Simple grid-tie system, will this work?

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    Tim,

    I did not find any current links that had much in the details of regulatory approval for this inverter.

    In my humble opinion, these types of inverters will never receive regulatory approval in North America for connection to the US grid.

    I don't know if this inverter is SWEA brand or not--But a few years ago we had a SWEA spokesperson hear say that SWEA was close to NRTL (UL/CSA/etc.) approval for their GT units--but we never heard anything again from him.

    Whether or not this GT inverter is a good/safe unit or not (I do not know), the issues with how North American Home wiring is done, the requirements for proper structural mounting and ground of the solar panel(s), etc. will never "be legal".

    On the power company side, they "hate" GT systems of any kind (costs them revenue) and only allow GT solar/wind systems because of state and federal government rules that "force them" to allow GT connections (with company and local building department, and sometimes local civil engineer, sign-offs).

    Towards that end, power companies are starting to look more closely for any utility customer that has a "different" power usage... Whether it is using too much power or too little (possible a marijuana growing operation) or somebody "illegally" connecting GT solar--They are installing new meters to address these issues.
    1. Computer billing that looks for non-normal monthly power usage
    2. Meter Readers looking for solar panels on roofs
    3. Meter Readers looking for meters running backwards
    4. New(er) meters which do not run backwards
    5. New(er yet) meters which only "run forwards" and will bill you for the excess power you generate (i.e., raise your power bill if you generate more than you use)
    6. New "Smart Meters" with report power running backwards, "strange" current wave forms which may be related to guerrilla GT solar.
    7. In some states (like California)--It is technically illegal to go off the grid and generate your own power (solar and other GT). You could be required to pay the utility for not using your expected/historical amount of power (solar/wind GT has a special exemption--They will prevent large customers/businesses from going off-grid without paying for stranded capacity).
    Otherwise, the Enphase and other Micro Inverters (200 watts or so) are here, perfectly legal, and being installed in large numbers for smaller and larger arrays.

    But, they are done to code and with building permits. And they are NRTL Listed for safety and tested to FCC limits.

    Again, not saying yours will not work--it is just not the "proper" way of doing things. Let your conscience be your guide.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Tm PV1
    Tm PV1 Registered Users Posts: 3
    Re: Simple grid-tie system, will this work?

    The inverter doesn't affect line quality (voltage, frequency, power factor) as far as I can tell. Our internet modem has a power factor of about .6, and the inverter is between .7 and .9. Only generating about 30 kwh a month isn't much and the meter doesn't even stop, regardless of feed in. There is about 500 watts of phantom load and I generate about 130 watts. As for the panels on the roof, unhook the inverter and it's an off-grid battery system. I mainly use the inverter as a dump load for excess power coming in to protect my batteries.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    It depends if the GT inverter is sine wave or not, and probably other things too...

    There is a poster here who worked on a project for a power company to see if they could analyze the user's power with a smart meter to fine if they were doing things like guerrilla GT solar.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Jburgess
    Jburgess Solar Expert Posts: 130 ✭✭✭
    Re: Simple grid-tie system, will this work?
    BB. wrote: »
    1. Computer billing that looks for non-normal monthly power usage
    2. Meter Readers looking for solar panels on roofs
    3. Meter Readers looking for meters running backwards
    4. New(er) meters which do not run backwards
    5. New(er yet) meters which only "run forwards" and will bill you for the excess power you generate (i.e., raise your power bill if you generate more than you use)
    6. New "Smart Meters" with report power running backwards, "strange" current wave forms which may be related to guerrilla GT solar.
    7. In some states (like California)--It is technically illegal to go off the grid and generate your own power (solar and other GT). You could be required to pay the utility for not using your expected/historical amount of power (solar/wind GT has a special exemption--They will prevent large customers/businesses from going off-grid without paying for stranded capacity).


    -Bill

    Bill,

    Good list. I might add to it logging and reporting power failures. Date, time and duration. A power failure not concurrent with a general outage can result in an inspection.
  • Tm PV1
    Tm PV1 Registered Users Posts: 3
    Re: Simple grid-tie system, will this work?

    The inverter is pure sine. I run a radio and a tv on the same circuit and the only interference is on the AM band. Everything else is fine. As for power outages, we usually don't report it unless we know other people are out, too. It's kind of nice without power for a day. The phone isn't ringing, the meter isn't spinning, but we still have some electricity through my off-grid portion and we can still cook, gas range.
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Simple grid-tie system, will this work?
    BB. wrote: »

    On the power company side, they "hate" GT systems of any kind (costs them revenue) and only allow GT solar/wind systems because of state and federal government rules that "force them" to allow GT connections (with company and local building department, and sometimes local civil engineer, sign-offs).
    This is not necessarily so. Here in Austin, for example, the city-owned utility has a progressive solar rebate program that they instituted on their own. It's worth it to them to get distributed generation on line because it delays the necessity of building new power plants, which is a huge investment for them. IMO, any utility that resists the incorporation of DG systems is merely being short-sighted.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    The problem is because solar (and especially wind) is not available on demand (scheduled power, or very predictable day by day)--So far--I have not read of one region/country that has reduced their coal/other fossil fuel plants by one kW yet...

    For example, around 85% of California's electric power goes through this "power brokerage"... Take a look at the daily power peak today it is peaking at 5pm and still elevated power usage out through 8-9pm... Plain consumer rooftop GT solar power is not going to help limit peak generation/transmission requirements.

    And this morning's wind generation, is so far, dropping like a rock. There is this link (PDF) if you want to look at "yesterday's generation" (unfortunately, the graphs are not the same data displays/relationships--so it is a bit difficult to compare).

    Windsun posted this article a while ago (note, link is dead now--site lost their archives):
    There is no evidence that industrial wind power is likely to have a significant impact on carbon emissions. The European experience is instructive. Denmark, the world’s most wind-intensive nation, with more than 6,000 turbines generating 19% of its electricity, has yet to close a single fossil-fuel plant. It requires 50% more coal-generated electricity to cover wind power’s unpredictability, and pollution and carbon dioxide emissions have risen (by 36% in 2006 alone).

    Flemming Nissen, the head of development at West Danish generating company ELSAM (one of Denmark’s largest energy utilities) tells us that “wind turbines do not reduce carbon dioxide emissions.” The German experience is no different. Der Spiegel reports that “Germany’s CO2 emissions haven’t been reduced by even a single gram,” and additional coal- and gas-fired plants have been constructed to ensure reliable delivery.

    Indeed, recent academic research shows that wind power may actually increase greenhouse gas emissions in some cases, depending on the carbon-intensity of back-up generation required because of its intermittent character. On the negative side of the environmental ledger are adverse impacts of industrial wind turbines on birdlife and other forms of wildlife, farm animals, wetlands and viewsheds.

    We have city utilities (power, water, garbage, etc.) around our region too... They are not always operated to the same standards/goals as private corporations (and all the various flaws of human nature that apply to corporations too). And we have been left holding some very expensive debt/high cost of their "product" because of their actions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Simple grid-tie system, will this work?

    on the surface re doesn't have much of an influence because there isn't that much of it to make any real differences being limited to about 1% of production. do i think it has made a difference, yes and no. like us with gt systems in home, they don't see the real results of re sources because the loads are being fed directly in a remote area of the grid. all the power company sees is what demand is made upon them and they act upon that accordingly. our power meters won't show the actual re power produced, but only the power required from the utility.

    the problem is that they have to have some generators running on standby regardless if re sources are attached or not. we cannot say if it did reduce the need to the utility or not for these reasons, but it is possible re sources have knocked out the need for a generator at times especially in california where power is a bit tighter to come by and re sources more openly enlisted, but we can't know what loads where eliminated for sure by the re sources to know if it allowed a generator to not be placed into running even if on standby. i can see that it may have eliminated the need for another generator on standby at times, but with a 1% limit on re sources it would have been a rarer event and short lived.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    If you look at the second link to "yesterday's numbers"--Very roughly, "renewables" are about ~10% of California's power, excluding "Big Hydro".

    And Big Hydro is about (very roughly) 20%-25% of California's power (highly valued because it can be turn on and off very quickly with no-standby power costs)... So--we are already looking at upwards of 1/3rd of California's power as being "renewable".

    Of course, the "renewables" tend to be non-scheduled power but steady producers (industrial type like geothermal, biogas, and small hydro).

    The wind+solar is highly variable and overlaid on the steady state renewable power base (industrial renewables?).

    But we do have issues with any power source--Big Hydro is causing big headaches for "big" Wind+Solar producers... Recently, the major dams in Washington State were generating lots of hydro power because of high water flow and environmental requirements (sending water over spillways causes high nitrogen gas levels in water which is damaging to fish--the "Bends" believe it or not--at least that is what the news articles say). And Bonneville power authority (Fed Gov) is shutting down wind/thermal turbines because of limited ability to dump power into consumer/commercial/industrial loads (transmission limits too?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Simple grid-tie system, will this work?

    with that 10% figure then i would say for certain that re, other than the hydro, has saved some killowatts there. it makes sense as you are not experiencing the same degree of power problems now that you had a decade ago and new generation plants are not being implemented there for many reasons that i won't extend to get into here.

    as to releasing the water through the turbines because fish are getting the bends, well it looks like they did not anticipate all scenarios and need to be able to release water without ramping up a turbine. flood waters are another condition that could present itself and the engineers did not properly see all possibilities that could arise.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    From what I can tell--We are not experiencing the "power problems" of 2000 because they built a whole bunch of natural gas fired turbine peaker plants... Plus they (I think) have removed some of the incentives to game the the state PUC regulatory/regulated power/brokerage system for extra cash (Enron/Los Angeles Power and Water) style.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Simple grid-tie system, will this work?
    BB. wrote: »
    From what I can tell--We are not experiencing the "power problems" of 2000 because they built a whole bunch of natural gas fired turbine peaker plants... Plus they (I think) have removed some of the incentives to game the the state PUC regulatory/regulated power/brokerage system for extra cash (Enron/Los Angeles Power and Water) style.

    -Bill

    so are you saying you don't believe re sources, excepting the hydro, have saved any need for further production from the utilities? just based on the exponential expansion everybody experiences with using more power as time goes on and population increases i guess they had to build more generating plants, but i think you aren't giving re fair credit in saving the utilities for they may have to have had more built to offset the 10% non-hydro re sources are providing.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Simple grid-tie system, will this work?

    Niel and others,

    If we want to continue this discussion--This thread should be split into two or three different locations.

    Originally is a 3 year old thread and a new posters asked some questions about plug-in GT inverters--which lead to this current discussion...

    But, my short answer, I would only count "steady state" renewables as saving fuel... Maybe about 2.5GW/35GW=~7% fuel savings (excluding Big Hydro--which is also excluded as "renewables" for some reason by the State of California).

    Not highly variable wind, and to a lesser degree solar which require spinning standbys or natural gas peaker generators virtually in 1:1 ratio for "reliable grid operation". There I would call it a "wash" on fuel and a waste of capital (as did the earlier article I posted about Denmark and Germany--as also mentioned by Marc's source in another thread).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Simple grid-tie system, will this work?

    we can halt the conversation here on this sidetrack and agree to disagree i guess as neither of us can prove it one way or another.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Simple grid-tie system, will this work?

    some interesting PDFs here on the subject
    https://solarhighpen.energy.gov/article/us_doe_high_pen_deployment_workshop_june_2011
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Simple grid-tie system, will this work?

    thanks dave. i'll read through them later and i'm sure it's going to be interesting reading.