Device to measure solar energy?

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edurbrow
edurbrow Registered Users Posts: 5 ✭✭
in Solar Beginners Corner #1
What device do I need in order to measure the energy I'm collecting with solar panels? I'm just getting started, got the stuff from a friend who upgraded and don't have much money to spend. I'm still connecting panels and building frames for them and I want to see what effect placement, tilt and adding of panels make. Right now I have a Solar Charge Controller that is 30A PWM. It only has 3 lights on it. I see green when it is directly sunny and the red one lights up if it is not sunny enough. It is night now and I just checked it, the amber light is on along with the red one. I would like something more detailed than that so I can see if the tilt panels and swivels I'm making make a difference.
I have two more Solar Charge Controllers, but they are 10A and 15A. They both have displays, but I haven't tried them yet because I figure more amps are better. Is that right? I have a multi-meter, but I only ever use it to test batteries and to see if AC is present. I know there are probably a range of prices from simple meters to huge things that send data to computers. What is a good starter for me as a beginner with just a few panels and batteries?
Also, what is a good meter to see how the state of the batteries are? I can use my multi-meter, but something more permanent would be better, if it is cheap enough. My inverter makes a loud warning sound when I've just run the TV off the system for not very long. Any advice is much appreciated.
TIA


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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
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    I use this for most day to day monitoring:
    https://www.solar-electric.com/bogart-engineering-tm-2030-a-battery-monitor.html

    ~ $200 with the required shunt.

    A much less expensive display I know little about:
    https://www.amazon.ca/gp/aw/d/B07ZJD34RZ/ref=sspa_mw_detail_6?ie=UTF8&psc=1

    A DC clamp amp meter is also useful for troubleshooting.  A good enough one is ~ $50.  Note, many clamp meters are AC only - you want one with DC amps.

    https://www.amazon.ca/UNI-T-Current-Capacitance-Resistance-Measurement/dp/B01FNMCA6Q/ref=mp_s_a_1_6?keywords=amp+meter&qid=1580053926&sprefix=amp+&sr=8-6

    It might help if you could list details (with web links if possible) of the gear you have, and what you want the system to do.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #3
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    To actually log the amount of energy harvested (WattHours or AmpHours per day), there are a lot of simple/cheap meters these days:

    https://www.amazon.ca/Electricity-Monitor-6-5-100V-Multimeter-Voltmeter/dp/B07KXCF8F8

    Don't know anything about the product, but these things are all over the place (Amazon, EBay, etc.). You do have to pay attention to how they operate... Some only log kWH in either direction, one direction, or add up as you remove energy from the battery and count down as you recharge the battery--And many times, from the description you cannot tell.

    There is a lot out there, both those that measure current with shunts (precision power resistors) or simply estimate with just a voltmeter and and internal timer (basically watch the battery voltage).

    Shunt based systems can drift over time (need to reset, or auto-reset for Battery Monitors--I.e., hold 14.x volts for 5 hours)... And the voltage only are pure estimates, but sometimes have neat features like has been >1 week since battery fully charged, alarm contact if battery bus voltage is low, etc.).

    https://www.solar-electric.com/search/?q=battery+monitor

    The "Midnite" meter is a "volt/time meter". The Xantrex, Victron, Bogart are shunt based (in general).

    And if you want more than you ever want to know about batteries, this website has lots of engineering details, plus a voltage/time based monitor (never have heard of anyone using it, but their knowledge of battery systems seems to be top notch, and lots of white papers where they share information):

    http://smartgauge.co.uk/

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • t00ls
    t00ls Solar Expert Posts: 245 ✭✭✭
    #4
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    the data for panel angles is already out there state by state.....it has been compiled also for time of year

    the only other way to get the max out of your panels with what you have is to have a dual axis tracker

    also...those PWMs are rated at those amperages.....doesnt mean they will put out that much  unless you have the panel amperage to put in them

    I'm sure if you give more information on your equipment ...you could get better advice...what panels, size of panels as far as volts amps...brand of PWM CC....what voltage your inverter is or better what model...and size of battery in Ahs

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