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  • #16
    Originally posted by SunEagle View Post
    Yep. Wind velocity and air moisture content can both affect material temperatures and IR readings. You just have to be aware of the environment to understand how it affects your temperature data.

    As for a 10" crawlspace under the panels as being "safe".. that is where I would be looking for a more permanent temperature measuring device. But if you got the time then go for it. Just be safe doing it.
    One of the other things I think I observed pretty consistently is that any individual panel's temp. seems to vary by several deg F. over its surface - even between adjacent cells. What I try to do is measure at 4-6 random places over each panel and form an opinion as to what a representative temp. is. I'll be among the first to say that it's probably not as precise as 16 individual sensors - one/panel, but perhaps more representative of reality over the whole panel - hard to say. That's part of the variability - where engineering "science" becomes a bit engineering "art". I've thought about a more permanent setup. However, unless/until I can find a way to get a better SWAG at an "average" panel temp. and not just one cell in a panel, I'll stick with what I have for now at least, but I'm more than open to suggestions. It really is a bit of a PITA.

    As long as there is no moisture on a surface, I'm not sure how air moisture content will affect the measurement of a terrestrial surface, but I'm certainly willing to learn. Most of the time, when I'm measuring anyway, the air on that roof is about as dry as a popcorn fart.

    Air moisture content as measured/correlated by the dew point temp. probably has an influence on the effective radiant sky temp. needed for measuring array to sky rad. heat trans. as the copious literature will confirm, a lot of which I have copies and some of which I had a hand in.

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    • #17
      Originally posted by J.P.M. View Post
      One of the other things I think I observed pretty consistently is that any individual panel's temp. seems to vary by several deg F. over its surface - even between adjacent cells. What I try to do is measure at 4-6 random places over each panel and form an opinion as to what a representative temp. is. I'll be among the first to say that it's probably not as precise as 16 individual sensors - one/panel, but perhaps more representative of reality over the whole panel - hard to say. That's part of the variability - where engineering "science" becomes a bit engineering "art". I've thought about a more permanent setup. However, unless/until I can find a way to get a better SWAG at an "average" panel temp. and not just one cell in a panel, I'll stick with what I have for now at least, but I'm more than open to suggestions. It really is a bit of a PITA.

      As long as there is no moisture on a surface, I'm not sure how air moisture content will affect the measurement of a terrestrial surface, but I'm certainly willing to learn. Most of the time, when I'm measuring anyway, the air on that roof is about as dry as a popcorn fart.

      Air moisture content as measured/correlated by the dew point temp. probably has an influence on the effective radiant sky temp. needed for measuring array to sky rad. heat trans. as the copious literature will confirm, a lot of which I have copies and some of which I had a hand in.
      One of the areas they taught us in the Thermography course was to be aware of both wind and air moisture content when taking a reading with the camera. Since a lot of the readings would be done on High Voltage gear you didn't want to get too close to the gear so the temperature reading could be at least a couple dozen feet away from the target. The moisture content of the air between the camera and target could diffuse the heat being radiated out from the target which would lower the reading and not give you an accurate measurement. So fog would be a bad time to take IR readings if you wanted very accurate temperature measurements.

      With your dry environment and the distance between your IR camera and target you shouldn't have to worry about fog or air moisture.

      [FONT=Comic Sans MS]Maybe just spiders and wasps that want to live under your array.[/FONT]

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      • #18
        Originally posted by SunEagle View Post
        One of the areas they taught us in the Thermography course was to be aware of both wind and air moisture content when taking a reading with the camera. Since a lot of the readings would be done on High Voltage gear you didn't want to get too close to the gear so the temperature reading could be at least a couple dozen feet away from the target. The moisture content of the air between the camera and target could diffuse the heat being radiated out from the target which would lower the reading and not give you an accurate measurement. So fog would be a bad time to take IR readings if you wanted very accurate temperature measurements.

        With your dry environment and the distance between your IR camera and target you shouldn't have to worry about fog or air moisture.

        [FONT=Comic Sans MS]Maybe just spiders and wasps that want to live under your array.[/FONT]
        It's not a camera it's a thermometer with a digital readout.

        The aperture is right up against the back of the panel when measuring.

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        • #19
          Originally posted by J.P.M. View Post
          It's not a camera it's a thermometer with a digital readout.

          The aperture is right up against the back of the panel when measuring.
          Based on how you described you temperature data gathering procedure I figured you were using that type of thermometer and that you were using it correctly. Those thermometers are pretty accurate if you use them as close to the target as possible.

          The camera I was referring to is made by FLIR and I guess I got carried away with explaining how they work.

          Sorry for any confusion to anyone reading my posts.

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          • #20
            Hi Mike,

            Thanks for your reply. The Bluetooth module that is currently used in the device is Class 2 with "up to" 10 meter range.

            I did look into using other wireless modules such as the zigbee, but as you mentioned, they don't interface so easily with [all] common devices such as smartphones, tablets and laptops etc.

            Also, keeping the costs down, really is my main objective. I'm assuming that if the entire device (including wires, sensors, power supply and case) is more than $90-100, then it just won't sell. Even if it does include an Android app with community-driven upgrades!

            Julian

            Originally posted by Mike90250 View Post
            re the Bluetooth radio, is this the short range (10ft) or the longer range (40ft) ? Have you looked into zigbee radio (but that does not work with 90% cell phones?

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            • #21
              Originally posted by SunEagle View Post
              Based on how you described you temperature data gathering procedure I figured you were using that type of thermometer and that you were using it correctly. Those thermometers are pretty accurate if you use them as close to the target as possible.

              The camera I was referring to is made by FLIR and I guess I got carried away with explaining how they work.

              Sorry for any confusion to anyone reading my posts.
              Understood. Thank you. I'm not as confident of the thermometer's accuracy as I am of the attempted consistency of my measurement methods and thus the precision of measurements, one 10 day period to the next.

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              • #22
                I programmed some updates into the Android app this weekend and made a video to demonstrate them.

                If you would like to take a look, the video is here: https://www.youtube.com/watch?v=r2Kt0Epz664

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                • #23
                  I have watched this video. Nice information and thanks for sharing. I will share this informative video with everyone.

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