should solar panels be "using" power?

cjmdwyercjmdwyer Registered Users Posts: 10
Our 2k grid tie p/v system has been online since April 1st. We received our first electric bill and both "smart" meters registered power consumption. The main meter on our "fusebox" where the old meter was located showed the highest kwh, but the meter on the box that leads up to the panels on the roof showed a kwh usage of 77kwh over 24 days. The only devices on this circuit are the solar panels/inverters. I checked with Enphase, and the night time draw on the inverters is only 30mW. I have 10 Canadian solar panels paired with Enphase micro inverters. I am getting between 12 to 15 Kwh a day out of the system. We are listed on the enphase site as Dwyer residence, where you can view system info. Any information on this issue would be great.

Thanks!

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    It looks like CJ's data is here:

    https://enlighten.enphaseenergy.com/public/systems/2nH73363

    I am not sure I understand the 77kWH of consumption over 24 days. This was the "old meter" that was re-positioned to be on the Enphase 240 VAC circuit to the PV Array?

    Is the meter wired to run "forwards" when the panels are generating power or run backwards when the panels make power--and if the meter is expected to "run backwards"--is it capable of running backwards (many meters are configured not to run backwards).

    Generally, you can get a Watt*Hour per turn on the disk (or electronic disk) and by timing how many seconds per turn, you can figure out the Watt*Hours being logged. Ideally, it should match pretty closely what you are reading from the Enphase monitoring system at any point in the day. If not, then there is a calibration issue somewhere.

    This website describes how to time the "spinning disk" to figure out the current "WATTS" rate of power generation--Several types of meters are explained....

    For the other, new meter, what is the monthly reading so far (and are you sure that it is reading backwards/forwards as you understand it)?

    What has been your average monthly kWH per month usage before the Enphase system was installed?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    the old "dumb" meter with the spinning disc was replaced by the power company with a Elster Rex meter that is used with "net metering". That smart meter seems to be working just fine. When they replaced that meter they also installed an identical smart meter on the solar disconnect panel. The information the power company sent me said that these meters take into account power flowing both ways and show a "net" usage. My question is why would there be any power flowing into the solar panels at all? I sent the picture that the power company sent me when we got these new meters installed. I have e-mailed them about this issue, but have yet to hear back. Somewhere I hear heads being scratched....
    All of the problems we had getting this system up and running were always due to "solar being a new thing" and "growing pains" according to the power company.
    IMG.jpg 250.7K
  • SpartanScottSpartanScott Solar Expert Posts: 41
    Re: should solar panels be "using" power?
    cjmdwyer wrote: »
    but the meter on the box that leads up to the panels on the roof showed a kwh usage of 77kwh over 24 days. The only devices on this circuit are the solar panels/inverters.

    Per Enphase you are generating an average of 13 kWh/day. Your solar meter should read about 312 kWh for the first 24 days. 77 kWh just happens to be 4x smaller than 312. Does the solar meter have a "x4" sticker on it telling you to multiply by 4?

    This should be an easy problem to figure out if you know your average energy use and grab some daily readings of both your solar and home meters. Check late night vs next morning reading on the solar net meter to see if you are truly loosing power at night.
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    I could understand the "array" taking some 1-10 watts or so at night--but that would be around 100 WH or 0.1 kWH per day type loads (standby losses).

    The 77 kWH per 24 days does not make any sense... I guess you generated around ~356 kWHrs during the time-frame.

    Electronic meters can be programmed to use current shunts (big precision power resistors) and for larger installations (such as an office building) they can program the meter to "display" the values read (say you have a 5x current shunt--1kW measured by the meter would really be 1kW*5=5kW displayed).

    The only "smart meter" error I ever heard of was because the utility mis-programed the smart meter and set the Shunt value to 2x--which doubled their power usage bill.... But that was something like a 1/2 dozen meters for the whole region.

    Ideally, in the middle of the day, turn off the loads in your home (no washer, drier, A/C, fridge, lights, TV, etc.--you can even flip off all of your home's breakers if you wanted--may have to reprogram your DVR/Microwave clocks) and see if the two meters agree (power from solar panels should just about equal the power going to the utility feed.... If they do not--you have an issue somewhere.

    I can read the power on my GT inverter and see ~2,500 watts and see ~2,300 watts going out to the utility feed (and meters numbers gong the right direction). In my case, I have a load of ~200 watts or so for fridge/freezer/computer network/etc....

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    These "smart" meters dont actually show me the amount of energy actually going out to utility in real time, as far as I can tell. There is just a little arrow that either point to the left or right and depending on how fast it is flashing shows amount of use. The arrow on the meter on the p/v disconnect box should always show arrow in the left or negative usage direction. I will look at night and see if it is just kind of in neutral and not flashing to the right or positive useage. Thanks for all the insight.....
  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: should solar panels be "using" power?

    These meters have 100's of options programming wise. I suspect the one on your solar/inverter circuit isn't programmed right, the only other possibility is you have loads on the inverter side, which by your description shouldn't be.

    One thing you can try to narrow down whats wrong is turn off the power at the breaker for that circuit at dusk back on near dwan and see how it effects the 24hr reported values compared to leaving on for 24hr
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    Smart Meters in our region tend to be programmed to display the one or more "billing registers" and the current Watt/KWatt power usage (on my electronic non-smart meter, the direction of the arrow is power in/out).

    So, I would expect that if you watch the meter, once very few seconds a different register would display--And depending on the setup, I would hope one of the registers looks like a wattage (mine is 0002.35 = 2.35kW or 2,350 watts average power in the last few seconds).

    I looked for a manual for your meter and could not find one--My meter also has a magnetic sensor too... I hold a magnet for a fraction of a second and it "starts the register reporting over again; date, time, peak usage, total usage, power). And if I hold the magnet for >5 seconds, it dumps a whole bunch of interesting information (including voltage, phase angles, power factors, amps, power, etc.). Pretty interesting (but mine is a GE meter--so yours may not do any of this).

    -Bill

    PS: We are also supposed to be able to read the 1 hour blocks of power data on the internet through our utility company's website--Does your utility offer a similar option?

    PPS: The way a utility varified that their meter was not working correctly was to, basically, turn off all loads and put a big electric heater on the home and time it for 15-60 minutes.

    Get yourself a Kill-a-Watt Meter and and 1.5 kW electric portable heater (yours or a friend's) and one evening plug it in and measure the results. You should be able to figure out the "LCD" readings. In general, the "rotating dial" is so integrated into so much Utility Law/Operation out there--I would be sort of surprised if your meter did not "flash" something once every 7.2 Watt*Hour (or equivalent).
    • 1,500 watts / 7.2 WH per rev = 208 revs per hour
    • 3,600 seconds per hour / 208 revs per hour = 17.,28 seconds per rev = 1.5 kW heater load (example)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    Our utility (Salt River Project) only offers a day by day power usage graph. I guess we received or "paper" power bill at home today and my wife says its long and confusing. I will look it over and maybe that will make some sense of all this. I can only hope!
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    I used to get an 11 page bill from our utility for Net Meter Time of Day power with our solar system... It had every regulatory point (reactor set-asides, fractions of a cent here +, others -, and stuff that hardly made sense)... Currently it is down to about one-two page statement, plus the "real bill" that just has a dollar amount that I have to pay (including gas billing).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dreesdrees Solar Expert Posts: 482 ✭✭✭
    Re: should solar panels be "using" power?

    I wonder if it's possible that the PV meter is reading "reactive" power?

    While the actual night-time power draw of the Enphase units is low (30mW/unit or 0.3w for 10), they do "draw" about 100 mA/inverter. This would be about 1A or 240VA for 10 inverters.

    This would be a bout 3 kVAh every day (basically whenever the sun isn't shining) which is very close to your 77 kW reading. The power factor on the Enphase units is very close to 1 when generating any amount of power.

    Read the meter when the sun goes down, then read it again when the sun comes up and see what the difference is to verify. Your meter should only be recording real power usage, not reactive power.
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    A good call on the KVAH vs KWH--Very possible. I like numbers that get close without a lot of hand waving. ;)

    Need to ask the utility what they programmed the meter to measure (a clamp on AC amp meter to measure current would give you a good idea)---Plus ask them how you are able to read the meter via the LCD panel (and if they have a "dial" equivalent).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • porkfarmporkfarm Registered Users Posts: 19
    Re: should solar panels be "using" power?

    I smell something fishy with the meter.. Why can't they just leave the old spinning disk up and let it run backwards for a credit. Just seems a bit too easy to have a "programming issue".

    Good eye's CJ for seeing the problem. Please update us, as my Enphase's will be going into production in 2 weeks.

    Off topic.. but does anybody remember the movie money pit ? The contractors famous line.. When will it be done ? 2 WEEKS...
  • pbartkopbartko Solar Expert Posts: 37 ✭✭
    Re: should solar panels be "using" power?

    If the utitility is like ours, Baltimore Gas & Electric (BGE), they only have to credit you excess energy generated for 12 mos. After that, they get it for free. You can only reduce your electric bill to zero, not get a check from them. With the old spinning meters, they won't be able to track when they can start stealling your excess credits!

    I'm currently waiting on a meter replacement to a new net-metering one so they can measure energy flowing both ways. In our case we wont' be generation more than we use with our 3.36kW system, so we won't be giving a way any free electrons.

    Pete B
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    Ok, turns out it was my power company was actually reading it as "power used" and not "power generated". Due to the way my billing cycle fell and switching out meters and switching to a "time of use" plan, they had to split my bill into two seperate sections. For some reason the first section, when we had the solar up and running, but not on time of use (April 1st thru 6th) we "produced" 77kwh. When they read it, they just assumed it was usage. When I got the paper bill yesterday, this was corrected and shown as credit against our "total energy demand" for that period in the net billing section. The second portion of my bill, when we switched to time of use (April 7th thru 24th) we generated 213kwh for that time period. These numbers seem about right according to the Enphase Enlighten system energy production report generator. That came in handy. I think everything will be OK from here on out. I guess I can chalk it up to another solar energy "growing pain". :D
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    Our utility (PG&E; Northern California) was (~6 years ago) well known for messing up the first solar bill--Mine went from $30 per month to $200 for 3 weeks--after we had GT solar...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,571 ✭✭✭✭✭
    Re: should solar panels be "using" power?
    BB. wrote: »
    Mine went from $30 per month to $200 for 3 weeks--after we had GT solar...

    You were consuming $30 of electricity before you installed the PV ? Wow!
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    No doubt, in the summer our bill gets close to $400 (august sucks!) Havent seen a bill below $100 in years...........................8)
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    Yea--we are a pretty cheap family... Most everything heating wise is done with natural gas ($20-$60 a month--winter heating is higher). No A/C and, at most, only a week or two a year would A/C even be useful.

    Worked pretty hard at conservation before we ever installed gthe solar GT system.

    Basically, around 200-250 kWhrs per month or so.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: should solar panels be "using" power?
    BB. wrote: »
    Yea--we are a pretty cheap family... Most everything heating wise is done with natural gas ($20-$60 a month--winter heating is higher). No A/C and, at most, only a week or two a year would A/C even be useful.
    Easy for you to say; here in Texas it's a different story. My house cost a lot less than yours, though, I'll bet. ;)
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?

    Your taxes are probably a lot less too. And you guys have jobs. :cry:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    Heating not too big of an issue here. Our heat pump hasn't been on since sometime in January. During the afternoon now when it is warmest, we have a portable evap cooler we run that is on the back patio. We will probably have to kick on the heat pump (A/C) sometime in mid may when it starts breaking 100 degrees. A/C is the big energy hog here. Can't go without it though, when it's still over 100 degrees at 10:00 at night........................
  • joeaksajoeaksa Solar Expert Posts: 39
    Re: should solar panels be "using" power?
    BB. wrote: »

    Bill,

    Thanks for the link. Love the display that the Dwyer family is using for their system. With graphics like this it sure makes it a lot easier to see how solar here in Arizona should be put on every house!

    Thx,

    Joe A
  • System2System2 Posts: 6,290 admin
    Re: should solar panels be "using" power?
    cjmdwyer wrote: »
    No doubt, in the summer our bill gets close to $400 (august sucks!) Havent seen a bill below $100 in years...........................8)

    I agree. My august bill becomes 450$. I can't take it anymore that is why I purchase solar panels to power up my appliances. ;)
  • BB.BB. Super Moderators, Administrators Posts: 32,606 admin
    Re: should solar panels be "using" power?
    I agree. My august bill becomes 450$. I can't take it anymore that is why I purchase solar panels to power up my appliances. ;)

    I guess you are in the Philippines--What type of solar system did you/are you installing? Grid Tied, Off-Grid or what?

    A USD$450 power bill is very large and takes a whole bunch of solar panels to offset using Grid Tied... And a whole bunch more money/panels if doing Off-Grid.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • cjmdwyercjmdwyer Registered Users Posts: 10
    Re: should solar panels be "using" power?

    Actually, a $450 August electric bill is not that uncommon in Arizona. With a 2500sqft or larger house and a pool, that is about right unfortunately. Winter, Fall and Spring are great, but the A/C works hard from about mid-May through mid-October most years...............:cool:
  • solar_davesolar_dave Solar Expert Posts: 2,389 ✭✭✭✭
    Re: should solar panels be "using" power?
    cjmdwyer wrote: »
    Actually, a $450 August electric bill is not that uncommon in Arizona. With a 2500sqft or larger house and a pool, that is about right unfortunately. Winter, Fall and Spring are great, but the A/C works hard from about mid-May through mid-October most years...............:cool:

    Agreed, my last year peak bill before solar was $600+.
  • joeaksajoeaksa Solar Expert Posts: 39
    Re: should solar panels be "using" power?

    Jeez guys, you must like it chilly.

    I keep my house at 77-78 or so and its been running $250 a month in summer. This is for a 2200 sq/ft place with no trees shading it in summer.

    Now switching over to solar and running the pool pump off of the panels and batteries and its cut my power useage in half, so its a big help.

    Joe
  • solar_davesolar_dave Solar Expert Posts: 2,389 ✭✭✭✭
    Re: should solar panels be "using" power?
    joeaksa wrote: »
    Jeez guys, you must like it chilly.

    I keep my house at 77-78 or so and its been running $250 a month in summer. This is for a 2200 sq/ft place with no trees shading it in summer.

    Now switching over to solar and running the pool pump off of the panels and batteries and its cut my power useage in half, so its a big help.

    Joe

    77F here on the 5 1/2 tons of AC, 2hp pump in the pool 6+ hrs a day. I cut my bill to $22 last month with about 3000kWh in the APS bank! ;)
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