Current and voltage monitoring of solar panels

Some time ago with help from the community i was able to finish a project for my friend who wanted to monitor a solar water heating system. At the beginning I wanted to make some analogue circuits to be able to read the temp sensors in parallel with the system but ended up with sniffing the data exchanged between the system and it’s main display. It was all described here: http://www.tinyclr.com/forum/1/3035

Right now the same friend want’s to add online monitoring of his solar PV panels. From what i know he has 24 PV panels connected in 2 series of 12 panels. I have attatched the voltage and current table.

My question is what are your suggestions of monitoring the current and volatage of this system?

Gralin,

something like this will work: http://www.sparkfun.com/products/10643

Let me ask a couple of questions.

The picture you showed seems very much like the back of a panel; is that just one panel by any chance? If so, then a string is 12*36v=432v, so the ~50v device shown may not last long

Secondly, what is this all connected to? It must be an inverter or regulator of some form (depending whether it is going to be grid-connected or if it’s going to off-grid batteries). Sometimes it’s easier to figure out what monitoring that device has, and monitor that instead. For my grid connected inverter, I just read the status info off the inverter directly that tells me what the actual V and I are as well as accumulated output to the grid. If your friend doesn’t the inverter/regulator already, you might suggest that they look at this feature as more than just a nice to have

Yes

I will ask him that and let you know ASAP

@ EriSan500 The output voltage will as Brett wrote around 400V and that board has 51.8V max.

My colleagues at work suggested using hall effect sensor for current and simple voltage divider for voltage (with aproporiate resistors values). What do you think ?

Take a look at: http://www.crmagnetics.com/ they provide a wide range of voltage/current sensors that have isolated outputs. When playing with high voltage you really need the output isolated from the input. Four hundred volts is unforgiving and will kill you, no second chances. Be careful.

Gralin,

sorry, didn’t do the needed math :-[