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If its your son's 5th grade science project, shouldn't he be asking the question?

Paul

I'd start reading this: 

http://openenergymonitor.org/emon/buildingblocks/dc-shunt

"If its your son's 5th grade science project, shouldn't he be asking the question?"

I second that. Agreed, there's a fine line between helping and "helping", but if you're the professional, you don't need to pass his exam, he needs to earn his pass for himself. Steer him by all means, but a major part of learning is finding out what you need to ask and how and where to ask it.

Sometimes, it would be a lot easier for me to write or modify a sketch or design a circuit for someone who's asked a question in these forums, but I always try to steer them towards finding the answer for themselves rather than spoon-feeding them. It's a variation on "Give a man a fish, and you feed him for a day; teach him to fish..."

+1 on what Robert said. He has done that for me quite a lot of times!

its funny to read "your sons project" yet...

Most of the documentation on this site revolves around measuring AC current. I am hoping that I can do this project on entirely DC current. I would like to monitor the solar provided power throughout the day and the also graph the power used by the Rpi (so the power draw off the battery) through the day.

What good ideas do you all have for where I should go next?

Clearly, its not your son's project any more haha

I find its a little bit over a 5th grade project, no way the teacher is going to pass him knowing the complexity and therefore external help he must had received.

You guys are harsh! Why not just answer the technical questions and leave the commentary unsaid? Not everyone wants their pre-teen child interacting with anonymous adults in a public forum, and your attitudes are exactly one good reason why.

Hello!

Dc monitoring is no problem, I've 2 modified EmonTX doing dc measurements at solar systems at the moment, both measuring voltage via resistance divider and current via a current sensor chip. One of the systems also has got an inverter so I measure the ac current there too. The other one has two current sensors for monitoring both: the current from the solar panel to the battery and from the battery to a load.

As current sensor I use ACS712 with different current values (5A & 20A), a 30A chip is also available.

If you want to know more about it I can give you the schematic.

This is all very good feedback. Thank you for your coaching. After reading up on many areas of this for over a week now, I realize how much more difficult this is just for me than when I started looking into it. Clearly, I'm very eager to persue this project, but it would make sense for me to go back to basics and see what my son could accomplish at his own pace.

I'm relieved to read that. Until I looked it up, I didn't realise that what you call "5th Grade" is actually the final year of what we call Junior School. I think you are probably right that a project like yours will be too much. Building and understanding the basic emonTx might stretch him a bit, but he should be fine with some guidance and explanation. But taking it further to include other components and assemblies and interfacing those will need research into manufacturers' data sheets and an understanding of electrical engineering probably beyond a 10 - 11 year old.

Fronius: I think you might be speaking for yourself when you mention "anonymous adults". I am using my proper name, and so is another contributor to this thread. I am a Chartered Electrical Engineer and if you feel so inclined you can check on the Engineering Council or the  IET website what that means. I believe another of the moderators here is a retired policeman. Rest assured that if any improper conduct comes to our attention, it will be dealt with very quickly.

Hello!

If you only want to measure the dc voltage and current of a solar panel you can use the standard EmonTX, add two resistors as voltage divider for the voltage measurement and add a ready to go module with the ACS712 with a second voltage divider (ACS712 works with 5V, the arduino with 3,3V).

I buy my ACS712 (modules and single ics) from chinese ebayer's, the 5A module costs about 2,50 Euros, less than the single ic.