Measuring photovoltaic installation

[wvm]

Hi,

I'm building a solar panel installation in Africa this summer and I'd like to be able to monitor its usage in the succeeding months.
The solar panel installation itself has been more or less designed. I'll need to measure 6 to 7 different signals.
I want to measure DCV (up to 150V) twice, DCI (up to 120A) twice, ACV (around 230V RMS) once, ACI (around 30A RMS) once and optional the AC frequency, but that's rather redundant.
This year, a team already tried, using Arduino Mega and dedicated circuits they designed on their own. However, the price turned out rather high, and the circuits were not too accurate (read 1%-5% deviation). Other small issues popped up as well.
I was thinking to use a Raspberry Pi Zero, to cut the costs, with a MCP3008 A/D converter, because its gsm modules are cheaper (the used connection to send the data). However, the circuits are too big costs for the low accuracy. Is there some kind of ready-to-go solution on the market (dedicated voltage and current meters), which would turn out relatively cheap? Most provide unnecessarily high accuracy for an unacceptable high price.
I'm aiming at 250-300 euros max for all circuits or multimeters together.

Thanks!

 

[BradtheRad]

If I had constructed the instruments myself, I would be glad to have 1-5% accuracy. The changeable nature of weather is so much greater.

To take measurements is not too difficult by itself. The hard part is the physical installation (of sensors, wiring, etc.) into your custom PV installation, and making decisions about the proper spot to install each component. You'll need to gain a lot of knowledge yourself (unless you bring in another team to do it).

After shopping around for a few weeks, you may find a supplier who offers high quality for medium-low prices.

Resistor dividers are used to take voltage readings.

To take Ampere readings can be by:
* low ohm resistor
* length of wire
* hall sensor
* coil made for measuring current