How can I meter an array?

heynow999
heynow999 Solar Expert Posts: 80 ✭✭✭✭
in General Solar Power Topics #1
I am an installer in Ontario, Canada

I am going to install a 10 kw system on a flat unshaded roof that I own. What I am considering is using my system to do some side by side comparisons because it would be a good site to do so. I would like to see for myself which technology is best. I am thinking of using one type of module (Siliken) with 5 kw of Enphase inverters and 5 kw of Tigo and an SMA inverter

The system would be grid-tie, feed if tariff. All energy would be sold to the grid. What i would like to do is place a meter between the inveters and the load center so I can measure what each side of the system is producing. The electricity would then go into the grid. I could just use the Enphase website to track production, and the display on the SMA but I would also like to be able to check the accuracy of those devices.

Any suggestions for an inexpensive way to accurately meter each side of the system?

Suggestions on how to do a proper comparison are welcome.

I would keep track of module position so I can know exactly how much power each 5 k should output by using the flash tests for each module. I would also sort the panels for the string side to match panel output.

Thanks

Peter
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: How can I meter an array?

    You might look for some used/old "dumb" mechanical utility meters that can log power in both directions. (some meters may have a one way ratchet that you can pull off and restore bi-directional logging).

    Just put a socket in each branch circuit and start logging... The meters should be accurate to ~+/- 1-2%.

    The other thing would be to find one of the Whole Home logging systems that support net metering and use them with the computer interface--certainly much more appealing if you are looking for automated logging. (accurate logging of the AC side current/voltage is pretty easy--the DC side is a bit more of a problem with accurate/isolated sensors).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #3
    Re: How can I meter an array?

    I bought a couple reconditioned utility meters from Wholesalesolar. You can google thier address. I looked to see if our host had them before posting this and didn,t see them. Also There is always a lot of them on EBAY. :Dsolarvic:D
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  • Frxddy
    Frxddy Solar Expert Posts: 113 ✭✭✭✭
    #4
    Re: How can I meter an array?

    I bought one from eBay. I just did an eBay search for "electric meter 240" and found several for cheap.

    You will find a small difference between meters on the same array. Each one is not 100% accurate and each one is distanced by the wires and associated losses. They will be close, and should be consistent, but not exact.
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  • heynow999
    heynow999 Solar Expert Posts: 80 ✭✭✭✭
    #5
    Re: How can I meter an array?

    Has anyone tried Locus energy for monitoring? I talked to them and the base unit looks like it can do what I need.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,022 ✭✭✭✭
    #6
    Re: How can I meter an array?

    I think if you read the microFIT rules carefully (and call to find out) you'll find that there can't be anything between the utility meter and the system. I'd love to be wrong. And by the way;, the Envoy from Enphase meters the power generated at the panel, not what you get paid for. I find my Envoy over-reads by at least 1.5%. Hydro One has metered and paid for 21.5Mw and my Envoy reads 22.1Mw since commissioning.

    What about having 2 separate 5kw systems...it's only $6 per month per account (if you really want to see how they compare for future customer information).

    Ralph
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  • tecman
    tecman Registered Users Posts: 13 ✭
    #7
    Re: How can I meter an array?

    Go to: http://www.hialeahmeter.com/

    Very reasonable prices and they also sell accessories like meter bases. They are re-certified utility meters, that most utilities and jurisdictions accept for generation monitoring. Wire it with the line to the inverter and load to the feed-in panel and it will register KWH generated.

    paul
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