Measuring amps

quique
quique Solar Expert Posts: 259 ✭✭
in Solar Beginners Corner #1
What's the simplest easiest way to measure amps from my solar panels with an ampmeter?
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  • James
    James Solar Expert Posts: 250 ✭✭
    #2
    Re: Measuring amps

    For temporary testing purposes or permanent monitoring?
    Individual panel or array measurement?
    What type (if any) of meter do you have now?
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #3
    Re: Measuring amps

    For quick temporary measurements a DC capable clip-on amp meter is the simplest.

    For a permanent setup, a shunt, or an open loop or closed loop hall effect current sensor can be used.

    A resistive shunt on negative terminal can be used but must be aware of grounding implications particularly with GFI function of controller. Putting it on positive leg is possible but must deal with the voltage potential from ground. If the meter circuit is totally isolated from ground then there is no problem.
    http://store.solar-electric.com/mka-100-100.html

    An open loop hall effect sensor uses the magnetic measurement of hall effect sensor in the gap of a torroid core with the feed wire going through the torroid donut hole.
    http://www.allegromicro.com/en/Products/Part_Numbers/0756/index.asp

    A closed loop hall effect sensor is similar to open loop but has a feedback amplifier that feeds a counter magnetic generating coil to drive the magnetic field in core to near zero. This makes the closed loop sensor more accurate since the core operates near zero net field eliminating much of the torroid core magnetic non linearities.
    http://www.sypris.com/test-and-measurement/magnetics-fw-bell/closed-loop-sensors
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  • nsaspook
    nsaspook Solar Expert Posts: 396 ✭✭✭
    #4
    Re: Measuring amps
    quique wrote: »
    What's the simplest easiest way to measure amps from my solar panels with an ampmeter?

    If you input is below 50A a simple panel meter works well for a visual reading. I use one of these on my setup.

    http://www.newark.com/jsp/search/productdetail.jsp?CMP=ILC-1c127onlinecatalog&sku=55F5257

    Partsexpress has some 30A cheap models I've used in a few projects. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-233

    More meters. http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=954&CFID=13387164&CFTOKEN=84761813
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #5
    Re: Measuring amps

    I have an ohm ammeter but not sure how to use it and I can't find the
    manual,. I read somewhere you have to put the + lead and the - lead on the same wire at different places and connect the + and - of the panel together but I need to make sure before I blow something up or burn my panels.

    My other option would be to buy one of those clip around meters I know!
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #6
    Re: Measuring amps

    Multimeter typically can only handle a maximum of 10 amps and not very well. They use separate terminals which is just a piece of calibrated shunt wire between the separate terminals.

    You want an amp meter to have low resistance.

    You can buy a 100 amp shunt ($24) and one of the 200 mVdc digital LCD displays for about $7. http://www.mpja.com/prodinfo.asp?number=6929+ME. You can set the decimal point position with jumpers on the DVM module. 1 mV equals 1 amp. The 3 1/2 digit meter will only give you 1 amp resolution.

    If you want 0.1 amp resolution get the 4 1/2 digit DVM for about $19. http://www.mpja.com/prodinfo.asp?number=7160+ME
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #7
    Re: Measuring amps

    When you measure amps, you have to "cut the wire" and bridge it with your Amp Meter (rated to carry the needed current).

    If you are not sure of what you are doing, or have a lot of circuits to measure current on (temporary connections)--Look for a Clamp On Amp Meter.

    There are two major types. Clamp on that can measure AC current only (transformer type coupling). Easy and pretty accurate to use.

    The other major type uses a magnetic sensor (transistor) that can measure AC or DC magnetic fields. Great for use with DC--but it is not that accurate (zero will tend to drift--especially at lower current readings--also much more expensive).

    Here is one for $100:
    400A AC-DC AND AC/DC CLAMP METERS


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: Measuring amps

    Sir,
    .
    May I ask what device you chose to monitor your amps?
    .
    I have looker at the TED and the eMonitor, they do tons more than just read your amp out put but they cost tons more too......
    .
    As they say, you get what you pay for????

    Thank you, glenn
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #9
    Re: Measuring amps

    The original poster was looking at the DC side of the solar / battery system of measuring current.

    The others you are taking about measure AC amps on the utility side of the system... More or less, completely different hardware and sensors.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • cfcw
    cfcw Solar Expert Posts: 25 ✭
    #10
    Re: Measuring amps

    I'm got a watts up meter and love it. It's great for experimenting. i have mine wired with powerpole connectors so that I may swap it from device to device. It's a lot of bang for the buck, very portable, and just a couple ma off what my fluke meter says it should be. I have a doc watson meter on order, too.
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