Is monitoring system amperage useful?

[Paul_NJ]

Last year we installed small digital voltage readouts at our solar stations in Malawi, one for battery voltage and the other for solar array voltage. Inexpensive, visible, and much easier to read than the meters on the MPPT controllers, they have held up well and range up to 30 vDC. Unfortunately I had forgotten that a panel array operating at nominal 24 v can well exceed 30 v in bright sunlight, so I’ve got to upgrade the voltmeters on the arrays. The same manufacturer (DROK) has a 0-100 vDC unit, with dual V/A readouts which would resolve the array voltage measurement. But is the current measurement also useful? I could put a shunt on the array line, or the battery charging line to monitor amperage as well as voltage, which would only cost me about 7 watts of energy loss. But is monitoring amperage really useful? I’d think array current and battery current would tell me the same thing, but is there a preference?

Thanks

[adoublee]

I would think it to be useful if it was free. What is the consequence of dropping the load (and not knowing why) or premature battery failure?

[Sunking]

But is monitoring amperage really useful? I’d think array current and battery current would tell me the same thing, but is there a preference?

If you have a MPPT controller, panel current, and chargging current are NOT the same thing. Charging current will, or should be, much higher than panel current. Depends on how you set the panels up. If you connected the panels in parallel (wrong thing to do) charge current will only be slightly higher. On the other hand if you wired the panels in series, the charge current will be much higher.

Example let's say you have a 500 watt, 24 volt system using 250 watt 72-cell panels. Each panel Vmp = 36 and Imp = 6.9 amps.

If you wired the panels in parallel, the current input on the controller = 13.8 amps. and output = 20.8 amps
If you wired the panels in series, the current input on the controller = 6.9 amps, and output = 20.8 amps.

So are the current useful? Well to some degree yes as it is useful as a diagnoses tool. Having said that, if it were me I would opt for something more useful, power meters. Power meters are more useful because they tell you how much power is being generate and used. Not only do they read current and voltage, but also measure Power, Watt Hours, and Amp Hours.