uLog for monitoring solar water heater performance

I am developing a solar water heater product that will convert a standard tank water heater to use solar energy. You can see a schematic of my product at solarstocker.com.

One of the problems that I anticipate is sizing the collector to match the households hot water demands. It is not a good thing the have the collector too large because the excess heat must be dumped by boiling water. It is also not a good thing for the collector to be too small because it will not make enough hot water.

So I thought it would be a good thing to have a low cost data logger that can be left with a new installation that would monitor the performance of a newly installed solar hot water system over a 30 dayvperiod to be sure that the customer will be satisfied with the system performance.

I want to measure the temperature at the top of the collector, at the top of the storage tank and at the bottom of the storage tank. This data-set of three temperatures would tell the story of the system performance. The temperature sensors in my controller run on 5V and have an output of 500mV @ 0 degrees C and 1500 mV @ 100 degrees C. I figure that at a sample rate of 1 data-set every 5 seconds the memory would hold 30 days of data.

So here are my questions about he uLog:

  1. Can the uLog keep accurate time over 30 days?
  2. Can the uLog be programed to take a data set every 5 seconds.
  3. Will the uLog run for 30 days on three AAA batteries?
  4. Can you assemble everything that I need into a package? ie: 1. uLog, 2. USB interface, 3. Open source software to download the data into a 30 run chart that plots the three temperatures.

There is a lot going on in this market right now. The federal government is offering a 30% tax credit for solar water heater for the next six years. This something that every installer should have in his tool box so it will likely be a decent market.

Right now I have a full plate with other developments and I do not have the programming skills.

Can you put this package together for me?


The uLog doesn’t have that accurate of a clock, and I don’t think it will last anywhere near 30 days on your AAA batteries. The uLog is a Sparkfun product, so we would generally not be interested in doing much development for that. Have you asked them your questions? I’ll add a data logger that is capable of what you’re looking for to our development project list, but it will likely be at least several months before we have anything since we already have a lot of other products in the works.

- Jan