Including a solar thermal system in our power meter project?

 I think it'd be excellent to include a solar thermal system in our project.  Ideally, of course, it'd be a local solar thermal system.  But if we can't get a local solar system with suitable measuring systems installed then Benny's Mum's system is better than nothing.

One important thing to note is that the temperature reading on its own isn't all that interesting, instead we want either the instantaneous energy production (in watts) or the cumulative energy produced over a defined time period (e.g. kWh per day) (IIRC, Benny's Mum's system displays both of these statistics).  These are the same units that we're measuring with our electrical meters (so we can do easy comparisons between solar hot water systems and PV systems).

Why is the temperature reading alone not particularly interesting?  Because it doesn't tell us how much power is being produced.  Consider two identical systems on neighbouring roofs.  In household A, they make extensive use of the hot water.  But the residents in household B are away on holiday.  The temperature readings for household A will be significantly lower than the temperature readings for household B because household B isn't using any of the available energy so it accumulates.  But both systems are receiving exactly the same amount of solar energy and it's actually household A that's capturing more energy.  What we want to measure is the power produced.  This can be calculated if we know the temperature increase across the solar panels (i.e. the temperature difference between the water going into the panels and the water leaving the panels) and the flow rate of water through the panels (analogous to voltage (potential difference) multiplied by current (flow rate) equals power (rate of energy transfer).

It would be possible to retrofit the necessary sensors to an existing system but I think it would require draining the system and cutting into the pipe to install the flow rate meter (although it may be sufficient to just detect when the pump is running and make an assumption about the flow rate although this will be less accurate).

I'd be very impressed if the AVIC kit can easily plug into a solar hot water system (even a sophisticated one like Benny's Mum's) using off-the-shelf modules.  I expect we'd have to hack something together ourselves, which shouldn't be tooo difficult.

Thanks,

Jack

 Hey Jack, thanks for all this!  

In terms of technical requirements, as I understand it, AVIC's LegioBox connects to anything that produces digital output.  What the LegioBox does is then send that digital output to the website in Holland.  Hugo, is that right?

In terms of "local" solar thermal users, Benny's mum is using a "very nice German kit" made by Ritter.  Maybe if we contact them directly they may know of local users [although such local users may not want to be disturbed by us]?  Or maybe we ask Benny nicely - btw I'm going with him to an architecture lecture next week and to talk more about retrofitting/heritage conservation issues, so I'll run the idea past him then.  

I suppose the first thing is to think about whether it will, in principle at least, be technically easy to link the Ritter system to the AVIC website.  Hugo, what do you think?

bw

Anna

Earlier this morning I started a forum thread on the excellent Navitron forum:

Hi,

great idea! Ritter produces OEM panels where the rest of the system could be from a different manufacturer, their own product however indeed includes LCD display, see http://www.paradigma.de/de/Service/Info-Material/Broschueren-Download/ for the main brochure and the Systa display brochure. If you can find out which display Benny has we can see how to link the LegioBox (which can process any metering output digital or analog electric) or other communication option, it is after all a potential market for AlertMe (get a text on your phone when system is overheating)!

atbH