I am not bothered by non-designers who come up with designs that actually work. What bothers me is graphic designers who create artistic renderings of things that could be useful products, except for the small fact that the thing they rendered has no hope of working, as it completely ignores basic engineering principles.
Wow…anyone want to bother to calculate how much energy they’re wasting right off the top from going from battery to mains back to battery there? It’s not like you could do much but charge a phone on that thing.
A situation I’ve run into multiple times:
CLIENT: Here’s my pencil sketch. Can you make this look real in Photoshop?
ME: Sure, is this for a presentation, a brochure, or…?
CLIENT: It’s a proof of concept. Just make it look as real as possible.
(two weeks later)
ENGINEER or PRINTER or STAGE MANAGER: Hey, about this rendering you did. How did you expect this to function or work or be built? Why are you rendering stuff without knowing how to make it really function? What are you, stupid?
sighs Guess it’s math time, because I’m actually interested in this now.
Slow charging on a phone is 1 amp, 5 volts, so 5 watts is what we need. We have an EU plug here, which is 35mm wide. Let’s say the diameter of the green area is 45mm then: that gives us pi*(45/2)^2, or an area of 1600 mm^2 roughly.
Now we start being very generous. The average amount of power falling on a 1 square meter is 163 watts. 0.0016 m^2 for our area, times 163 watts, we get 0.26 watts at 100% efficiency. Solar panels aren’t 100% efficient: the absolute best we have, unconfirmed, is over 24%. Let’s say 25% because it makes the math easier. 25% of 0.26 is 0.065 watts if you do the best possible thing, which is to lay it down on a sunny part of the ground in a flat area.
For those of you keeping track at home, that’s a little less more than 1% of what a normal slow charge on your phone is, and it’s a little over a t of what your phone consumes in sleep mode. The nearest thing it matches is the power used for the antenna in your home wireless router.
Nicely done! And yes, you were very generous. Normally you’d derate a panel 3% to 5% for weather soiling of the intervening window glass. And of course full rated efficiency can’t be achieved without constantly actively tracking the sun’s position.
“Designers” can be just as bad. I remember seeing a conceptual design for a “washball” which was a manual washing machine that would be dragged or attached to a bicycle. We’re looking at about 500 kg of water to drag around (plus the energy you need to create turbulent agitation) as an “easy” alternative to hand washing. It looked fabulous. It wouldn’t have worked. A hand-cranked or stationary bicycle inertial agitator would have been better. The sad part is that it was supposed to help people in areas with no or low electrical connectivity. Washing clothes by hand consumes massive quantities of labor, so it’s actually important to consider the issue of non-electric clothes washing.
Yeah, I think I did specifically state “If we put it facing up outside on the ground when it’s noon literally all the time.” I also left off the loss in power from converting, like I mentioned way up, from solar panel DC to AC for the mains. That’s not too easy to estimate without knowing their actual circuit though, but I could probably dig up numbers.