mine daughter is make the efforts to strength a remote control car that currently uses 4 AA batteries as power. She is make the efforts to transform it to solar. What go she should do so?


Solar cars space really hard since solar panels room so inefficient.

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The energy in sunlight varies greatly by latitude, weather, and also time that day. On a clean day, at solar noon, at equitorial latitudes, solar strength at Earth"s surface have the right to be a little over \$1000\:\mathrmW/m^2\$. However, it"s much lower at other times the the day and latitudes. For a reduced bound, the WMO defines direct sunshine as anything over \$120\:\mathrmW/m^2\$. Clouds and also smog of course have the right to mean even less.

Additionally, we don"t have any type of really efficient converters of sunlight to electric energy. Also the most effective seem to be about 35%, with the species that aren"t research projects or only obtainable to NASA coming in around 15% efficient, according to some rapid research I just did.

So let"s i think this vehicle is huge enough to assistance a dashboard the dimension of one A4 paper of paper. That"s \$210\:\mathrmmm\cdot 297\:\mathrmmm \approx 0.06\:\mathrm m^2 \$ of area obtainable to collect light. Just how much energy is available? In the worst case:

$$ 0.06\:\mathrm m^2 \cdot 120 \:\mathrmW/m^2 \cdot 0.15 \approx 1W $$

In the ideal case:

$$ 0.06\:\mathrm m^2 \cdot 1000 \:\mathrmW/m^2 \cdot 0.15 \approx 60W $$

What have the right to we carry out with around one watt? maybe it"s best to compare to the battery in the car. It looks prefer the 7.2V battery packs supplied in plenty of RC cars has a capacity of \$3000\:\mathrmmAh\$ (three amp-hours). We can obtain a very rough idea the the total energy in that load by multiplying the voltage by the capacity:

$$ 7.2\:\mathrm V \cdot 3\:\mathrmAh \cdot 3600\:\mathrm s \over 1\:\mathrm h = 77760\:\mathrm J $$

A watt is one joule every second. So, the price of energy obtainable from the solar panel is around the exact same as if friend drained the battery constantly end a period of 77760 secs or 21 hours. How progressively would you have to drive that car to do the batteries critical 21 hours? That"s how fast it deserve to go with the price of energy easily accessible from the solar panel.

Using the finest case that 60 watt is somewhat much more favorable, yet it"s a same guess you will desire the car to work-related in much less than optimum conditions. In practice of food you will gain something in between.

With some an extremely careful design you can get something the works, however it"s never going come zip roughly like a battery-powered vehicle can. It help a lot to allude the panels straight at the sun, yet to save them pointed at the sunlight as the auto drives would require a very complex mechanism. In addition you"d most likely want come go with every part of the car and also make it as effective as possible. Minimization rolling resistance ~ above the tires. Minimize any transmission losses. Usage a very efficient motor. Make the vehicle as light together possible, etc.

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These space rough calculations, the course, but serve to show the point: solar cars are hard. If they to be easy, everyone would be steering them.