meters for solar
I think having a meter is an excellent idea. I have larger solar electric systems in two of my buildings, I run my refrigerator, freezer, washing machine, lights, water pump of the systems. Having a meter is essential to keep track of how your system is performing. In a larger system having a hand held meter will be a good backup to your system metering, in a small backpack system a tiny meter would let you know if your batteries are charged or still need some time to charge.
Hint.....
If your system uses a MSW (modified sine wave) inverter, you will either need a "True-RMS" type meter to measure the inverters output, or at least be aware of the fact your readings will be different than expected. Since the MSW inverters output wave form is not a sine wave (has steps, not a smooth waveform), your non RMS meter will display a lower voltage than you expect, something like 90 volts. The inverter will be working perfectly, just displaying a lower voltage because your inexpensive meter expected a smoothe wave shape. You may not want to pay the extra money for a True RMS type, just measure the inverter output before a SHTF situation and keep in mind that you will be measuring a lower voltage.