ehsab avatar image
ehsab asked

Setup to monitor solar yield


I would like to setup a testsystem to evaluate the solargield for a year.
I was thinking of one 24V 300W mono panel connected to a BlueSolar MPPT 75/15 and a 12V batterybank.

How should i design the load, i need ideas what to connect and how to set it up so that it uses 100% of what the panel can produce, without cycling the battery too much.

I also have a Venus GX i could use for this test.

Kind Regards

MPPT ControllersSolar Panelmonitoring
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1 Answer
Mark avatar image
Mark answered ·

You probably have 3 options to do this;

1. Using a full system always operating in max power point mode (your proposal)

2. Using a small solar panel with a known suitable size resistor placed across its terminals and measuring/logging voltage, then back calculating power and energy yeild

3. Using a dedicated irradiance sensor and measuring/logging the data from that, then calculating power and energy yeild

With a full setup you will need to manually setup something to constantly keep the battery below the target charge voltage and accordingly the MPPT in max power point mode.

You could possibly use a simple on/off voltage triggered relay to turn on/off a load or the generator start/stop function in the Venus GX. For the load I would just pick something simple and suitable in power draw, like some high power resistors, a small heating element or some light globes.

If you want to get more sophisticated you could get/make a PWM modulated power output and control system to constantly vary the load to maintain the battery voltage at a setpoint below the target, rather than to cycle it (but this is probably out of scope).

Then you can track the solar yield via the MPPT 30 day history and/or the VenusGX and VRM.

Also note that there should/may be a proper weather station close by that formally records all meteorological data including solar yield. The data is also typically available for free download online, so maybe also consider this potentially much simpler option first.

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