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Posted by LML999 on May 18, 2007, 4:30 am
What do people use for tracking the performance of their solar hot
water heaters?

What are the important metrics?

What kind of tools - temp sensors, data loggers, etc, do people use?



Posted by Anthony Matonak on May 18, 2007, 7:51 am
LML999 wrote:

Most ordinary folks don't track the performance of their solar
hot water heaters beyond the point that it's working or not and
how much it reduces their utility bills.

That said, the solar water heaters I've seen usually have at
least a couple of temperature gauges on them. One each going
to and from the solar panels.


Posted by spamtrap on May 19, 2007, 6:40 am
 On 18 May, 10:51, Anthony Matonak

That is probably true - not that I know for sure, but it sounds
reasonable. Of course many other things can affect utility bills so
that is at best a guide.

I have seen on the WWW that Dallas 1-wire sensors are used a lot. They
seem to be cheap and easy enough to work with, but I have no
experience of them myself.

I am monitoring my system because it is fairly new, still in its first
year, and I want to know how well it works. The controller has 4
temperature sensors. That information is interesting but on its own is
quite meaningless as temperature alone is only part of the picture. I
want to know the output in KWh and for this I also need to know the
volume of water heated, I put a standard water meter from the local
hardware store into the pipework. Using this and a stopwatch I was
able to measure the flow rate in litres per minute with the pump
running at full speed. I entered that value into my controller, and it
does the rest. It keeps a running count of the KWh produced and I
check it daily. That is adequate for me to know the system is not
performing nearly as well as I had hoped :~(

Posted by dold on May 19, 2007, 3:59 pm

I monitored my PV installation closely when I first turned it on.  Then I
monitored it occasionally, now I read the meter on days when PG&E should
read their meter.  I try to glance over and make sure the green light
is on on a daily basis.  I would notice the change in my utility bill ;-)

Someone in the PV group put a little wifi webcam in position to monitor a
PG&E meter.  I suppose that could be logged with some sort of time-based
program capturing occasional pictures.

Clarence A Dold - Hidden Valley Lake, CA, USA  GPS: 38.8,-122.5

Posted by Christian Kaiser on May 19, 2007, 6:38 pm
 With my system my datalogger directly supports calculation of the energy
by the flow rate and the in/out temps.

I verified that by my own calculations to be accurate within about 10%.

(see http://www.invest-tools.com/pub/solsys  for a description)


LML999 wrote:

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