Hi, I just bought my first solar panel ( SP200l) and was getting around 160-170w in full sun, but it drops to a consistent 28w with passing clouds, is this normal? Also it only has 3 stand stands which is annoying the hell out of me, anyone else have the same model?
Solar panels generally work in the visible light spectrum. Therefore, output is variable according to conditions. I have 6.6kW of on roof solar (5kW inverter), half on either pitch of the roof as the roof is east-west facing. Here in Australia, I get close to 50kWh of output at this time of year (summer). In August last year (winter) I had 1 day where output was only 7.5kWh, or around 15% of current daily output. So, yes, this is normal, however you don’t state your location.
Output at the equator will exceed northern or southern latitudes as the sun is directly overhead and travels less distance through the atmosphere (I’m at 34 deg S). Also, there are solar cells that will work better in lower light as they also produce power from UV & IR spectrum light, but most portable panels don’t use these cells and they are more expensive.
I can’t comment on the 3 stands for 4 panels as I have a different brand with a stand on each segment. I do peg them down when used as they have eyelets on the panel and the end of each leg to assist stability.
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Thanks for your reply, I’m in the South Island New Zealand 
Hi @Macketti, We believe this is a normal situation. Cloud cover can significantly reflect sunlight, which affects solar charging power.
Therefore, we recommend customers charge during midday when the sunlight is stronger. Additionally, adjusting the angle of the solar panels can help find the optimal orientation.
Kindly notice some factors that affect the rate of charging when using solar panels.
a. The amount of sunlight
b. The conversion rate of solar panels
c. The angle you place the solar panel
d. The length of the solar cable
@Mandp’s response was very professional and accurate. Thank you for your help!
@Macketti
You are around 10 deg further south than me, however your panel (Bluetti specs) has adjustable legs. Around 45 deg tilt should be the best and if you have the panel out all day, move it to face the sun 3-4 times to optimise the output. When I do this it’s approx 0900, 1200, 1500, that way I get 3 or more hours in one setting.
They don’t call your neck of the woods “land of the long white cloud” without reason, lol. It was over 43C here today, 40+ yesterday, so although plenty of sun it also drops my panel array Voc by around 3.5V due to the heat. This afternoon around 3pm it got cloudy even at that temp and solar went down by over 75%. It is what it is. 
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Thanks for the info, much appreciated. I’m playing around with 35-45 but the intermittent cloud makes it difficult to judge. We have a balmy 20c today, I feel for you guys over the ‘ditch’, 40c+ seems common now and will only get hotter
An easy way to get the right angle and orientation is to put a tumbler or similar, upside down on the panel. If it casts a shadow left to right, swing the panel around until the shadow disappears. Do the same for up/down with the tilt.
You will need enough sunlight to cast the shadow, lol.
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