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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Yes, a significant drop in wattage with passing clouds is normal for solar panels as they rely on direct sunlight. The SP200L is likely similar in this regard to other panels. Regarding the three stand stands, some portable solar panels, including Bluetti models, do use a three-leg design. You might find other users discussing this specific model in online forums or reviews for Bluetti products.
Adding my two cents into the pot: When it is overcast or the Sun is completely shaded by clouds, light is diffused and therefore omnidirectional. In scenarios like these you will have higher solar potential when the panel is laid flat because of the diffused light. In other words, when its overcast, a flat panel produces more power than a tilted panel. If the Sun will peak in and out during the day, ALWAYS tilt if possible to maximize potential. What you want to achieve is a perpendicular angle to the Sun (or 90 degrees). So if the Sun is at 45 degrees altitude in the sky, you would tilt the panel 45 degrees to make it perpendicular. What a lot of people do is simply tilt their panel in the configuration where it will be during solar noon and slightly beyond, because that’s when you will get the most power. Between say 12-3PM in the summer. The drawback of these foldable panels is that you have to find a way to stake them to the ground when its windy out so they don’t blow onto their face and damage the panel, and you can’t use them in the rain as they are not IP68 rated. This means you have to baby them. If its sunny out at 12-1PM then a thunderstorm rolls in at 2PM, you have to put away the panel, and then if its sunny again at 3PM, redeploy it. So likely a portable foldable panel only makes sense in regions where it doesn’t rain constantly (ex: florida, PNW, etc)
@Macketti Is on the South island of New Zealand, they don’t call it the “Land of the Long White Cloud” for nothing, lol.