Quote:
Originally Posted by skysurfer
2860kJ / day (the 250l is a day yield) = 2860000 J / 86400 s = average power of 35 W.
The size of the panel is 1.65m * (assumed ?) 1m = 1.65m2 which collects 1650W when exposed directly to the Sun.
Efficiency = 35/1650 = 2.2% and not the "15%".
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To be fair, there are at best 12 hours per day of sunlight (averaged over the year), and a couple of hours per day may not have sufficient intensity to reach operating requirements (and that's before we account for clouds etc), so the overall efficiency is probably 2 to 3 times higher than your estimate.
The article states:
"The solar panel measures 1.65 meters long—roughly the height of a kitchen refrigerator, or this reporter—and has a rated power output of about 210 watts."
The Solar Constant is about 1.36 kW/m2, so if their unit is producing 210 watts of usable hydrogen energy (released by combustion), that is not too far off the claim of 22% efficiency.
They'll need to produce more information to back up their claims before it becomes clear that generating hydrogen to burn for energy (or power a fuel cell?) is a better solution than direct solar to electricity. At the end of the day, a lot will come down to overall system efficiency, and the relative costs of storing energy in gas tanks or batteries.