Solar Irradiance Meter

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Does anyone use and recommend an inexpensive solar irradiance meter? The only one I found via a web search is one by DayStar for ~$140 at: http://www.zianet.com/daystar/solar_meters.html

Is one worth it for checking on a solar panel system's actual efficiency?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Solar Irradiance Meter

    I am not sure that it is worth getting one to check panel efficiency... If you want to make one your self, just get a single, good quality, mono or poly crystalline cell and connect it to a amp meter (or DVM set to amps). The shorted output of a silicon solar cell is pretty proportional to irradiance

    Measure the output of your solar array and the output of your single cell in milli-amps (single cell should be temperature stabilized too) of of your single cell. Now wash your array and let the temperature stabilize again and take another set of measurements. Do this a few times and you should be able to track your array's performance. You should measure and record the temperature of both your array and single cell too...

    In the end, I am not sure how useful a calibrated watt/m^2 measurement is... You really need accurate temperature readings too. If the meter is not temperature compensated--it becomes just another source of differences.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #3
    Re: Solar Irradiance Meter

    The meter may be useful, but probably not by itself. You'll probably also need an MPPT charge controller, a shunt in series with the module/array, a high quality DVM (to measure module voltage as well as shunt voltage drop to determine module current), and an IR thermometer to measure PV cell temperature, as power output is cell temperature dependent.

    HTH,
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #4
    Re: Solar Irradiance Meter

    For me, I can check the PV shorted output amps in full sun and if it's in the ball park, I forget about it. I can't tell you what to do, but me? I'd put that $140.00 on another PV.
    Wayne
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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Solar Irradiance Meter

    Thanks!
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: Solar Irradiance Meter

    Hello,
    A solar irradiance meter kit is available at http://www.microcircuitlabs.com/SIM.htm

    Best Regards,
    Jeff Fedison
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Re: Solar Irradiance Meter

    Jeff,

    It looks like your company is producing some very nice small, inexpensive, yet very useful devices there (including logging solar irradiance and temperature devices).

    Also, your home built/kit solar irradiance meter is nicely documented--no send $25 for a PDF document to build your own.

    Look forward to seeing what else you will have in the future.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: Solar Irradiance Meter

    Buy it. Is will be the best $140 you ever spent.
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  • System2
    System2 Posts: 6,290 admin
    #9
    Re: Solar Irradiance Meter

    I have 40 solar photovoltaic panels on the roof of my two-story house. In considering what maintenance I should do or have done on the panels (including cleaning the front glass of the panel), I have decided to purchase an inexpensive solar irradiance meter to determine the degradation of the solar energy through the glass.
    I would compare the solar watts/m2 in front of my house measured by the meter to the total kilowatts from the panels at that time. The reduction in the total kilowatts from the panels for the same solar watts/m2 should be the reduction in sunlight through the panel front glass and the aging of the solar panel. Also, the change in the ratio of panel kilowatts to meter measure watts/m2 shows a degradation in the system performance.
    The panels were installed on 04/12/2011. I don't expect much degradation of the glass surface from weathering to date. The installing company said that rains would keep the glass clean. A service magic company offered to clean the panels and stated their solar panel customers typically did it once a year after the spring pollen season.
    I just want to independently judge when the panels need cleaning, and I plan to clean them myself because the service magic company offered to clean the 40 panels for $425 each time.
    From my search of the internet, Micro Circuit Labs offers the least expensive solar irradiance meter. $85 for a 0-to-2 watts/meter2. All other meters I found were at least twice this price. <JND>
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #10
    Re: Solar Irradiance Meter

    $425 is about 25-30 % of what 40 panels will produce in a year depending. That's almost as bad a Enphase wanting 6-7% ($2.00 per inverter ) for their monitoring service.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #11
    Re: Solar Irradiance Meter

    You can just buy a small crystalline solar panel and measure the short circuit current through it...

    If you gt a panel rated at Imp = 1 amp--Call that 100% at 1,000 w/sqm sun. And compare that with the current coming from the solar array (Imp is relatively temperature independent and much more accurate at measuring reduction in light output).

    If you wish, use the Micro Circuits link and you can buy a kit or even build your own with a digital panel meter and small resistor from his documentation.

    If you change the photo diode or use a solar cell--you probably will need to change the shunt resistor value.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #12
    Re: Solar Irradiance Meter

    I use a fire nozzle on a hose, to get water up to the panels, and rinse them in the cool AM, before the sun hits. the water just arches up and falls on them, I'm not pressure blasting them. I just do it when they look dirty/dusty in the summer. Pollen in my area just risnes off. If I had hard water, I'd do a final rinse with a car wash deionized cartrige.

    Mr-Clean-AutoDry-SystemAutoDry Filter removes spot-causing minerals during your final rinse, allowing your car to dry in minutes before your eyes
    Includes a filter life indicator that changes from black to brown when it's exhausted
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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