Solar monitoring

slurry bowlslurry bowl Registered Users Posts: 25 ✭✭
Hey everyone.

What is the best way to monitor the wattage being generated at the back-fed breaker from the solar and at the mains.

Id like a simple real time graph showing energy usage and energy generation. I think my customers really want this.

Im aware of the approach using Current Transformers and either RF or wifi to share the data.

Ive found lots of products online, but very little reviews.

Any thoughts appreciated.

THANKS

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,061 admin
    Re: Solar monitoring

    At least one person here is using a TED:

    www.theenergydetective.com

    They have a version that works with a Grid Tied AC inverter... But it may only work properly with a GT inverter where it assumes that the power is always generated by the GT inverter--Unlike a Hybrid inverter that can push power to the grid or pull power (for recharging, running protected loads).

    I could not tell from reading the specifications (from a year or so ago)--If you have a hybrid inverter (solar+battery GT/Off Grid inverter), you may have quite a bit fewer choices.

    There are a few people here rolling their own energy monitors too.

    https://www.google.com/search?q=site%3Aforum.solar-electric.com+open+source+energy+monitor

    Hopefully, some of our members can talk more about their projects.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar monitoring

    I've got to say this:
    When it comes to monitoring a GT system the only numbers that count are on your electric bill. If there is a discrepancy between what you think you're producing and what they say you're selling back it is 99% likely to be your consumption. Even using something like a TED to differentiate between GTI output, consumption, and grid Watt hours in/out doesn't guarantee the utility numbers will match.

    In my opinion people get obsessed with monitoring, as though every single Watt produced is some sort of personal triumph. Then when the production falls they panic. We've had people do so as the season changed because they were under the impression output would be constant. We've had people do so because the output didn't match the panel Watts or inverter Watts.

    Averages matter. Moment to moment monitoring doesn't. Check that the system produces within range when installed and stays within range from one month to another. Don't worry about every minute of the day.
  • solar_davesolar_dave Solar Expert Posts: 2,367 ✭✭✭✭
    Re: Solar monitoring

    Actually Monitoring has helped me several times to detect problems and get the thing diagnosed pretty easily. Like the single string fuse being blown, the monitoring lead me to the reduced output.

    I will second that something like a TED is only an indicator for what you should expect on your bill. For me it is mostly because the TED software doesn't do my sort of net-metering properly. When the raw data is collected and run through a program that "simulates" the utility methods of billing, we are usually within 1-2%. Even then there are so many what ifs on my bill with all the weird charges they list. It does record kWh but I to would want clarification from TED that the results would be as expected for a hybrid situation.
  • ButchDealButchDeal Solar Expert Posts: 35
    Re: Solar monitoring
    BB. wrote: »
    At least one person here is using a TED:

    www.theenergydetective.com

    They have a version that works with a Grid Tied AC inverter... But it may only work properly with a GT inverter where it assumes that the power is always generated by the GT inverter--Unlike a Hybrid inverter that can push power to the grid or pull power (for recharging, running protected loads).

    I could not tell from reading the specifications (from a year or so ago)--If you have a hybrid inverter (solar+battery GT/Off Grid inverter), you may have quite a bit fewer choices.

    There are a few people here rolling their own energy monitors too.

    https://www.google.com/search?q=site%3Aforum.solar-electric.com+open+source+energy+monitor

    Hopefully, some of our members can talk more about their projects.

    -Bill

    Mu system is hybrid and I have a TED5000 (as well as a new TEDPro in testing). Both work fine with the hybrid system. The key for my configuration was to
    put both input leads for the inverter through the Solar MTU/CT. This nulls out the grid power that goes through the inverter to the emergency power and only counts solar production, the other MTU/CT is on the mains and shows energy NET. Between the two numbers everything is calculable.
    Here is my pvoutput results: http://www.pvoutput.org/intraday.jsp?id=31117&sid=28507
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: Solar monitoring

    Look into openenergymonitor.org for this, if you have a DIY bent.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • slurry bowlslurry bowl Registered Users Posts: 25 ✭✭
    Re: Solar monitoring

    Thanks everyone. I have looked into TED and they seem to make a quality product.

    I was very impressed with all the organized data on the PVoutput website. That is amazing and a huge resource to have.

    I install mostly residential and light-commercial systems. While almost all of my systems inverter manufactures provide some kind of monitoring (Solaredge, Enphase, SMA, Fronius)....
    My customers are often asking for a simple way to compare how much they used over a given INSTANT/HOUR/DAY/MONTH with how much their GRID TIED system generated.

    I know this is possible my diligently comparing their utility bill and its billing cycle with the KWH generated and recorded by the inverter for that same time window, but this can often be confusing for customers.

    What Im looking for and will perhaps try to design is a simple system that will use Current transformers on the PV GRID TIED back-fed breaker AND the main conductors entering the home. By comparing these two, I should be able to distinguish production and consumption. Im going to use a RasberryPi microcontroller to record this data. I would ideally like to see two graphs fluctuate in real time, allowing a homeowner to hold a tablet computer and reduce loads to get under their solar generation threshold. Now I know solar input is ALWAYS changing, so this may be a frenetic graph, but I think the idea is worth trying. Perhaps a final product will be a simple screen that has two kWh figures on it for each month.

    I like the open-source ideas and greatly appreciate this forum. THANKS
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Solar monitoring

    This sounds like the product you're looking for: http://www.theowl.com/index.php/energy-monitors/solar-pv-monitoring/intuition-pv/ but I think it's 50hz, 230V only.
  • jebattyjebatty Solar Expert Posts: 56
    Re: Solar monitoring

    My Aurora microinverter system with the data device for the system provides via the web the graphic info you are seeking: real time for each of the 26 panels, daily on a 15 minute sampling, 7 days, 30 days, 12 month, week to date, month to date, year to date. Data is down-loadable to a csv file that can be used by other programs for custom reporting and graphing.

    My system also was installed with a power production electric meter (not utility required, but suggested by the installer as a means to check the utility buy-back billing accuracy). So, the power production meter measures power from the array going into the main panel, and then there is a utility required meter to measure buy back kwh, plus the utility usage meter. The meters have verified that the utility bills are accurate.

    There is a small discrepancy between the software provided power output of the system and what the production meter reports: software 6953 kwh to date, production meter 6883 kwh to date, a 1% discrepancy. I don't know exactly the cause of this, but I'm guessing that the system consumes some power at the array, there is some line loss over the 280 feet of cable between the array and the meter, and perhaps there is some sampling point vs real time discrepancy. Regardless, the difference is not material.
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