Building a solar pv monitor kit

Hi. I am a semi-retired vet with no electrical skills, but reasonable problem solving and surgical skills, my husband is a webmaster and has programming skills. We built a radio kit that required some soldering but found it challenging. Have we any chance of putting together a solar pv monitor kit?  Our pv system is complicated and needs monitoring that detects negative and positive flow - the set up would be type2, and this system seems superior to the wattson solarplus- I like the monitor better, more info. Does anyone put them together for amateurs like us?

calypso_rae's picture

Re: Building a solar pv monitor kit

Have you had a look at my Mk2 PV Router design?  There's plenty of info about it at . [and here - RW]  This design allows surplus PV power to be efficiently diverted, but does not support any recording of data.

If you want to monitor & display data as well as diverting surplus power, Martin's approach at may be of interest.

Both of the above designs will work on the standard emonTx platform (Although I generally use a shared Vref, my Mk2 sketch will work fine with independent non-buffered ones).

Building a basic monitor is very straightforward and plenty of instructions are available.  By constructing your own rig, you will gain a much better understanding of the basic principles than by simply using a commercial one.  The performance will probably be a lot better too. 

From recollection, the Type2 setup requires current to be measured at two places.  An alternative approach well worth considering is to measure voltage too.  By this means, real power (and other parameters) can be calculated directly.  When calculated in this way, power is much more accurate than when subtracting two values of current and assuming a nominal voltage. 


seiac's picture

Re: Building a solar pv monitor kit


Thanks for that. I have chickened out and gone for an off the shelf monitor- eco-eye pv. I am very interested in  open source monitoring but it looks very difficult to assemble the platform. 

Thanks again


calypso_rae's picture

Re: Building a solar pv monitor kit

OK.  The Eco-eye will no doubt give you some idea of what's going on, but its performance has been shown to be well down on the alternative designs that I and others have posted on this forum.  For a start, the Eco-Eye makes the assumption that the mains voltage remains constant at all times, which it most definitely doesn't.  However, several constructors have Eco-Eye units running alongside their own home-built platforms. 

For a budget of around £50, you could invest in the necessary components to assemble your own monitor (Arduino, breadboard, CT and AC/AC adaptor) and see how you get on.  A simple test circuit is here.  If it all works, then you'll have a top notch monitor which could be boxed up and used for real, with diversion of surplus power if you wish.  If you decide not to complete the project, at least you'll have had the fun of building something which detects current & voltages for yourself.

Robert Wall's picture

Re: Building a solar pv monitor kit


Susan & her husband's problem appears to be the practical mechanical & electrical skills needed to construct the kit! We need any army of volunteer assemblers - and I guess a standard price list for the service - for people who want an accurate and versatile alternative to the commercial offerings.

calypso_rae's picture

Re: Building a solar pv monitor kit

Some first-hand reports from people who were apprehensive at the outset, but then found that it was much easier than they imagined, might help too.

For me, assembling a kit is fairly straightforward.  I've yet to get around to putting it all in a box though - keep finding something else to do instead!

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