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Data Logger for a Solar System

Discussion in 'Home Power and Microgeneration' started by [email protected], Jul 27, 2013.

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  1. Guest

    Hi Everybody,

    I am looking for a data logger which collects data from my "Solar remote site".
    I can visit these sites every 4 to 6 months for maintenance and need to collect data on a memory card or on the internal memory of the device in orderto download them. Better will be if I could get the data over internet on my laptop as I have mobile coverage on Site (but this is not really mandatory).

    The data logger should measure and collect following data every 15 or 30 or60 minutes:
    - Date & time
    - Current: between “0 A” up to “250A” (4 X DC channels in order to be able to measure different sources)
    - Voltage: between “0 VDC” up to “60 VDC”
    - Temperatures: between “-5°C” up to “55°C” (3 or 4 channels inorder to measure outside, inside, battery temp)

    I need also all related sensor. Could anybody support me?

  2. Jim Wilkins

    Jim Wilkins Guest

    Arduino C is relatively simple to learn and easy to use. The program
    memory in the chip does wear out from too many Writes, though, like a
    Solid State Drive.

    Here is another isolated current sensor supplier:

    Shunts require very careful design to avoid common-mode interactions
    on the sense leads.
    Every wire and connection is a resistor that creates a voltage drop.
    Yesterday I measured 350mV of drop between the elements of my TV
    antenna with only 1A passing between them. Wiggling the rivet joints
    while the current flowed reduced that to 20mV, and I gained almost
    10dBm of signal strength.
    Three separate EL-USB loggers may be the simplest and cheapest
    approach if you can tolerate unsynchronized readings.

    If your electronic technician skill level isn't up to building safe
    and reliable circuits from scratch you might consider an old laptop
    and a USB DAQ. My Compaq Armada consumes as little as 7W at idle with
    the screen off, and can operate from an external 12V battery with the
    Auto-Air adapter. Spare batteries are fairly inexpensive for some
    common laptops like Dell Latitudes. It needs only a few minutes of
    remaining run time to move between chargers.

    A quick search for wake timers found:

  3. j

    j Guest

    On 7/27/2013 9:09 AM, wrote:> Hi Everybody,
    remote site".

    If you go Arduino you can get an SD card/ethernet shield combo. There
    are a huge number of available shields including cellphone. Arduino has
    limited memory and interface capacity without a "shield".

    Arduinos have A/D's for data logging and there are "1 wire" temp sensors
    that connect to the digital inputs.

    Arduino is easy out of the box:

    It's not the only micro controller out there. But it is widely available
    and cheap. You can find "sketches" of data logging and one wire temp
    reading that can be altered to suit fairly easily. The learning curve is

    Also available are Raspberry Pi's and Beagle Bone Blacks. Both run Linux
    and can be programmed in almost any language. Both also have analog and
    digital inputs and outputs similar to the Arduino but are also full
    fledged mini computers.


    to collect data on a memory card or on the internal memory of the device
    in order to download them. Better will be if I could get the data over
    internet on my laptop as I have mobile coverage on Site (but this is not
    really mandatory).
    able to measure different sources)
    to measure outside, inside, battery temp)
  4. Neon John

    Neon John Guest

    This kind of advice invariable comes from someone who's never actually
    done it before. As someone who designs this stuff for a living, let's
    examine that advice a bit more.

    It's true that the Arduino has 8 12 bit A/D converters of the
    successive approximation type. But there's more.

    * Typically there are 3-4 bits of noise on the converters and/or
    reference voltage so 8 bit data is the best that one can RELIABLY get.

    * The input is 0-2.54 volts (unless one hacks in his own voltage
    reference which brings in its own set of problems.

    * The processor starts executing spurious instructions when the input
    voltage reached about 2.6 or 2.7 volts.

    * that channel is blown when the input reaches 3 volts.

    * It has practically no static or transient protection.

    * The input impedance varies during the successive approximation so
    the input must be driven by a low impedance source (op amp or
    instrument amp).

    * the input is monopolar. Bipolar (AC) inputs make the processor very

    The field signal for each channel must be scaled or amplified as
    needed, zero offset, filtered, shaped, perhaps rectified and
    conditioned for each input port. This will cost many more dollars
    than the Arduino itself and will require a vast amount of time to get
    right. Much more money, in fact, than simply buying the proper data
    logger to fit the application.

    The correct answer to the OP's question should be another question,
    "What kind of physical data are you trying to capture? Most likely
    volts and amps. What else? Thermocouple input? Sunlight intensity?
    Ambient temperature? What range of temperature operation to you

    All that has to be known before any meaningful advice can be given.

    John DeArmond
    Tellico Plains, Occupied TN
    See website for email address
  5. Neon John

    Neon John Guest

    With what you've specified, you need 9 channels. That would push you
    into the expensive world of 16 channel data loggers. If you drop a
    temperature channel (you really don't need battery temperature) then a
    much less expensive data logger can be used.

    We need some more data before any hard recommendations can be made.
    For instance. do the inputs have to be isolated? That is, do they
    need separate grounds? If so that pushes the cost up significantly.

    If you can arrange your circuitry so that all inputs share a common
    ground then you can use a relatively inexpensive common ground system.

    Here's a typical relatively low cost unit.

    8 channel, current input, lithium battery powered, data collected via
    a PC. Enough memory to do 16 samples per hour for 6 months (if I did
    my math correctly).

    Most any variable can be easily converted into a current with low
    noise. That's why 4-20 ma is so common in industry.

    In this case, a simple series resistor would convert the 60 volts to
    say 1 ma. For current, either a shunt or a hall effect device
    measures the current and its output is converted to a current with a
    simple resistor.

    For temperature you can go simple and use a thermistor scaled and
    linearized to output a current. This device allows one to store
    per-channel scaling factors so the actual value doesn't matter much.

    Or you could go a bit more complicated and use an LM35 temperature to
    voltage IC

    The voltage output is again converted to current with a resistor. This
    (and the thermistor, for that matter) will require a small amount of
    power. You can rob that from the 60 volt input using a zener diode in
    parallel with the LM35 to keep the supply voltage stable..

    The LM35 draws worst case 136uA and needs from 5 to 15 volts to
    operate. I'd choose 15 volts to get the maximum range. The resistor
    is 60-15 = 45 volts /136uA = 330kohms. That would dissipate 6 watts.
    If your typical supply voltage is different than 60 volts then just
    substitute the numbers.

    This post isn't designed to answer your question directly. It's
    designed to get you thinking in the right direction. If you google
    "battery powered 8 channel data logger", you'll find hundreds of
    varieties. The Omega one was simply one of the first hits.

    John DeArmond
    Tellico Plains, Occupied TN
    See website for email address
  6. Jim Wilkins

    Jim Wilkins Guest

    What do you suggest as an alternative?

    I just discovered BatteryInfoView from NirSoft for logging the battery
    discharge on a laptop too old to have sensors that HWiNFO32
    recognizes. Some of his other programs like Produkey dig deep enough
    to trigger antivirus warnings.

    Several full discharge and recharge cycles have restored the capacity
    of the original battery in my 1999 Compaq from a few minutes to about
    an hour.
  7. Labjack looks good too. I havent personally used them, but I've heard
    good things...

  8. Mr Clarke

    Mr Clarke Guest

    You make it and I`ll make a better one and sell millions of them!
  9. Jim Wilkins

    Jim Wilkins Guest

    Thanks. The U3 looks interesting.
  10. No Body

    No Body Guest


    Some of the concernes you raise are addressed by this system:


    I will often used Dallas/Maxim One-wire devices, if the temps are in a
    range that they will deal with..

    Then again.. a data logger for an entire Solar System.. That's one big
    honkin machine!

  11. Jim Wilkins

    Jim Wilkins Guest

    Neon John's comments seem to apply more to a LabJack than an Arduino.

    I've been using an older Radio Shack PC-interfaced multimeter to log
    solar panel output. It's only one slow channel, but it's opto-isolated
    for safety and ground-loop immunity and can read AC or DC voltage and
    current, up to 20A. The newer model also reads temperature. There are
    several less expensive versions on-line.

    This decodes the serial data stream:

    and here are the bit assignments in English:

    I've ordered one of the cheaper ones to see if I can put together a
    3-channel laptop datalogger using the included software or a Basic
    program and a Cardbus dual serial port.

    When I was building electric vehicles I used a Campbell Scientific
    datalogger to record test runs.

  12. Jim Wilkins

    Jim Wilkins Guest

    Scratch off the clunky included software which is for one meter only.
    My QBasic test code that reads the older RS meter runs slowly in XP,
    so this will be a DOS project, maybe using the two multimeters as
    opto-isolated current sensors and my DI-194RS datalogger for DC

    Windows 7 includes a 6.22-style DOS that handles NTFS and long
    filenames. I found it while exploring POWERCFG options and piped the
  13. Guest

  14. Bob F

    Bob F Guest

    You had to include interminable SPAM to say THIS????
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