I have tested the short circuit current of two 100 W solar panels from TEMU and found they are under 700 mA in partial cloudy days. Once connected to solar controller, their output voltage drops to almost same voltage as lithium battery's. It means they have about 1 to 5 W charging power. I am going to test again in sunny days. Are they normal or faulty solar panels?
solar panel issues
- Thread starter Kai
- Start date
- Sep 4, 2011
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If you put a meter directly on panel leads before going in controller you usually have between 19 to 22volts. On a dull day around 16 volts
The voltage is correct as specified. But the short circuit current should be above 5A.
IMO best wait till we see the sun before making any judgement, and then ensure the panel is angled "normal" to the sun.
Depending on the technology of the cells employed they respond quite differently to reflected and direct sun beams, but in all cases you need the "light" power to be there and hit the panel for it to generate electrical power.
Depending on the technology of the cells employed they respond quite differently to reflected and direct sun beams, but in all cases you need the "light" power to be there and hit the panel for it to generate electrical power.
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So many people fall for this , thinking the solar panel will deliver the max output , remember the the panel will only produce its max rated power in full sun and at when at 90 degrees in both axes to the sun.Also as we are in the winter months the sun is lower in the sky and even at noon the incident light intensity from the sun is lower as the light has to travel further through the atmosphere. As the other posters have said wait for a sunny day in June before judging the panels ( or buy a 1000W light bulb ( metal halide or HP sodium) and illuminate the panel with that and measure its output)
Ian could you please inform me of which day in June you are referring to I can then put it in my diary and set my alarm so as not to miss it,many thanks Gary. 😄
- Sep 4, 2011
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Interestingly, at least to me, unless my Morningstar's meter is miss reading I have seen occasions where the Wattage read exceeds the panels rating, few but not many times. [it's an engineering thing this recording of data!]
I am assuming this is because the rating, as I know is based on a particular illumination standard, not necessarily the best illumination we might ever see.
Further interestingly this still happens on my now 19 year old Kyocera 85 Watt panel, so its not aging badly; though it is only used when camping, so in total it lives much of its life out of the light.
I am assuming this is because the rating, as I know is based on a particular illumination standard, not necessarily the best illumination we might ever see.
Further interestingly this still happens on my now 19 year old Kyocera 85 Watt panel, so its not aging badly; though it is only used when camping, so in total it lives much of its life out of the light.
Thank you for your inputs. I heard solar panel power can reach 80% of rated power supposed in fully sunny day. I am expecting 50% on cloudy day. A few watts doesn't make sense for off grid camping.
And you will quite likely get 50% on cloudy days, just not this time of the year here in the UK.
In summer with a high sun angle illuminating whiter clouds the yields can be well up.
In winter with those very cold days that freeze the moisture from the atmosphere giving bright sunshine and crystal clarity, then a panel aligned directly at the sun can give exceptional outputs. Here the cold also helps panel efficiency.
IMO without a large and aligned array it's unrealistic to think solar will yield very much in UK February weather, we just don't get enough light to the ground, and the hours of it are short, the angle is very low and typically winter is when we need extra electrical energy to be off grid.
It's quite a different and viable option come the better months.
In summer with a high sun angle illuminating whiter clouds the yields can be well up.
In winter with those very cold days that freeze the moisture from the atmosphere giving bright sunshine and crystal clarity, then a panel aligned directly at the sun can give exceptional outputs. Here the cold also helps panel efficiency.
IMO without a large and aligned array it's unrealistic to think solar will yield very much in UK February weather, we just don't get enough light to the ground, and the hours of it are short, the angle is very low and typically winter is when we need extra electrical energy to be off grid.
It's quite a different and viable option come the better months.
- Dec 27, 2022
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50%??
At the moment on a reasonabley bright winters cloudy day
My 4.3kW system on a south facing roof is producing 434W at the moment or 10%
My 130w flat panel on the van ten miles away is producing 11W so just under 10%
On a very cold sunny winters day I have seen the house system at 4.4kW so above it's rated output but that's very rare.
You will be lucky to see much more than 15% on a cloudy day.
- Nov 11, 2009
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What conditions are you prescribing for such a test? Britain has longer daylight hours, Spain has more sunshine, panels work best at 25deg so any test is somewhat irrelevant. You get what you get.
- Dec 27, 2022
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No but if you would like to move my house there I will.
If you fill in the fields accurately on:
JRC Photovoltaic Geographical Information System (PVGIS) - European Commission
Photovoltaic Geographical Information System (PVGIS)
Then you will get almost exactly what the panels will produce at whatever location, angle, direction you have set.
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