Portable panels can be highly-productive and useful, but good results require owner discipline.

Rated watts are rated watts; a 100w portable will make the same power as 100w mounted in a lab.

Portables can outperform flat-mounted panels when they are either

• set out facing ~south¹⁾ at seasonally-optimal tilt; or
• moved throughout the day to optimally face the sun. This can increase harvest over fixed tilt but requires frequent repositioning. To give you an idea, automated single-axis trackers that follow the sun automatically can increase yield over fixed tilt by 20-35%. Increases from occasional owner repositioning will be lower.

• owners not setting them out for whatever reason
  • laziness
  • “won't be here that long”
  • panel isn't waterproof and it might rain (or has rained)
• set out but fell/blew over face-down
• set out in overhead shade or high grass shade
• set out facing north (!!) ←- there are two rigs in my line of sight with this unforced error. Setting out facing east or west can make sense if direct sun is only available in that direction, or if one is manually “tracking” the sun.
• made of “flex” crystalline that breaks
• loose dogs pissing on them