track solar panel current with WebControl

[fwd03]

Ross,

You mentioned that you monitor your solar panel output by using WebControl. Could you please provide more details? I am trying to monitor my solar panel output also. I want to be able to compare them for effeciency, or any panel developed bad cell in it. I don't use battery and charger, all solar panel outputs running parallel directly go to grid tie inverter input. If I measure current from each panel, I am not sure the best way to wire them to the WebControl analog input. Are they share the ground, or share the high voltage side?

Thanks for your help!

 

[rossw]

Hi, the webcontrol terminal board described elsewhere here was specifically designed for this application - then a bunch of modifications made before I sent the boards off to be made to make them somewhat more "universal".

My solar setup is pretty typical "offgrid" but with some extra bells and whistles. The overview diagram is

The "Metering" box is 6, 10-amp moving-coil DC meters. Here is a picture during construction (the DC breakers have been finished, tidied up and covers put on since this photo was taken)

The meters are all in the negative (ground) side, so I can do "low-side metering".
3 channels go directly to the webcontrol board via my terminal/amplifier board, each amplifier is operating in inverting mode (because the solar panel side of the meter goes between 0V and -70mV).

I also got a seperate 1-wire 4-channel A/D input device which has 0-5V, and I made a 4-channel amplifier board - same design as on the web terminal board - to pick up the other 3 arrays, and the 4th channel measures the array voltage (so I can calculate watts).

Using a webcontrol for just that seemed a bit extravagant though - so it also does all the tracking, parking etc for the arrays.

One thing that *IS* important though, I had to use an isolated power supply so I could connect the WC ground to the solar ground right in the metering box.

 

[fwd03]

Thanks, Ross.
If I have ground from the point of inverter to connect to the ground of DC/DC 5V inverter, then have WebControl ground also connected to that point, with inverting amplifier, I could measure the current/voltage drop from each panel back to the point of ground. I think that will work.

I read news that Australia having record heat at 50 degree C now. With that kind temperature there, you could have a steam engine running! How is your solar panel doing in that kind of temperature?

Frank

 

[rossw]

Thanks, Ross.
If I have ground from the point of inverter to connect to the ground of DC/DC 5V inverter, then have WebControl ground also connected to that point, with inverting amplifier, I could measure the current/voltage drop from each panel back to the point of ground. I think that will work.

Cool. Just take care with ground loops and potential differences. PLAY SAFE! Double check things, and remember: some 1/8W 1R resistors are cheap insurance

I read news that Australia having record heat at 50 degree C now. With that kind temperature there, you could have a steam engine running! How is your solar panel doing in that kind of temperature?

Its not so bad where I am, we only got to 45.3 deg C (113.5 deg F).
Steam engine sounds like a great idea - except for the water it would need (which we don't have!)

My solar panels have been down a little bit on output because of their high temperatures, but still making over 3KW, which is plenty for charging my batteries.