A helpful monitor of solar installations?

BlakeFleming85BlakeFleming85 Registered Users Posts: 33 ✭✭

I've had multiple headaches installing solar systems for many reasons:  Faulty batteries, Lack of understanding about how it all works together, lack of tools (only have a simple multimeter), etc.  I'm trying to find an affordable tool that would allow me to have a bit more information about several small solar systems I need to set up.  Most are in Central America and central India to give you an idea of the sun availability.

Most will be 1-2 AGM batteries (no ability to properly monitor standard flooded cell batteries) of about 100 Ah each, 1-2 100W 12 or 24v solar panels, perhaps a couple of systems with 2-4 200w solar panels, and basic lighting (5-15 LED 9w-13w bulbs running a total of 4 hours a day).  I really don't need an inverter and I really don't need more than basic lighting and a USB port or two to charge a couple of phones.  I'd like the system to be able to run 3-4 days without full sun ideally.  

Any suggestions about what to buy, specs needed for the energy consumed calculations, etc. is fine.  But, one thing I seem to have problems with is the lack of proper tools to monitor the systems for simple, basic info.  

Can someone comment to tell me if installing something like the following would help me with simple, but helpful information for monitoring a small system with only about 200w of PA?   It is a:

LCD Display Digital Current Voltage Power Energy Meter



  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    While the unit you link to seems like a very nice power/energy meter--It only logs in "one direction". Depending on how it is wired, either current discharging from the battery bank or charging the battery bank.

    A true battery monitor works in both directions. If you use 50 AH discharge, it will take around 55 to 60 AH to recharge the battery (plus other things like if the battery is charging for 2+ hours, the meter will reset to 100% full).

    It really depends on what you want to do... Just monitor the current/energy out to loads, or back into the battery bank. Or do you want an energy "totalizator" that, basically, monitors the state of the battery (what is the state of charge of the battery bank).

    You can buy two of these meters (they are very inexpensive--However, I do not know anything about their quality) and wire them to the same shunt--Just one of them "backwards" from the other. Then you can see the total energy out of and back into the battery bank. Still would not give you the estimated state of charge of the battery bank--But still very useful/interesting information.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BlakeFleming85BlakeFleming85 Registered Users Posts: 33 ✭✭
    Thanks @BB .  Can you suggest a couple of options that you believe would be good quality energy "Totalizers" as you say?  A good battery monitor is what I'm looking for.  Just seems that when I recently had problems, I had nothing but a multimeter and the attached Charge Controller to provide me info.  That was pretty hard to use to narrow down the source of my problems.

  • PhotowhitPhotowhit Solar Expert Posts: 5,987 ✭✭✭✭✭
    Bogart Engineering has been the standard for a long time, they are shunt based measuring devices. I think a europeen company Victron also makes some shunt based meters.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    As Photowhit says:


    And just to give you some other ideas--There are voltage based monitors too (no current shunts):


    Shunt based monitors are probably better (more accurate)--But all battery monitors can "drift" if you do not set them up correctly, or you do not fully recharge the battery bank every so often.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    Not to counter any of the experts (I'm clearly not one myself), but...  That same unit that @BlakeFleming85 provided the link to is pretty much what I've gotten multiple of. As a battery monitor, all the the things @BB. and @Photowhit said are true. However, I do think these meters can be very useful in a system. I've bought two of them so far: One that will go on the PV side of my charge controller, and one on the battery side of the charge controller. For only about $15 each (the exact same unit is available on EBay for less than Amazon, and also with no shipping costs) it's a pretty cheap window into how things are working. I would like to add a third measuring the draw out of the battery to the inverter, but none of these models goes up to 200A, which I need. For the systems the size that @BlakeFleming85 is talking about, one of these little babies would do nicely.

    The two I have will give me the Amps, Volts, Watts, and cumulative Watt-Hours from my PV array into the charge controller, and out of the charge controller into the battery bank. Of course, I'm still waiting to install mine, as we can't get into the cabin to do the work until (usually) late May.


    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
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