Again....Solar Panels and Hydrogen Powered Cars

After Reading this great post from Karl: How big a solar panel would... I liked:

So the energy available to create hydrogen would be 137 to 411 kwh, per m2 of solar panel.
The energy needed to electrolyse water to hydrogen and oxygen (at 100 per cent efficiency) is 40 kwh per kilogram of hydrogen (source physorg.com).
So to get the required 175kg of hydrogen per year would need 7000 kwh of energy every year.
So the number of m2 of solar panel you would need would range from 17 to 51m.
Is this plausible?

I did a little search and found this on Wikipedia:
Buses, trains, PHB bicycle, cargo bikes, golf carts, motorcycles, wheelchairs, ships, airplanes, submarines, and rockets can already run on hydrogen, in various forms and sometimes at great expense. NASA uses hydrogen to launch Space Shuttles into space. There is even a working toy model car that runs on solar power, using a regenerative fuel cell to store energy in the form of hydrogen and oxygen gas. It can then convert the fuel back into water to release the solar energy.

I've followed the notes on the wikipedia's page and found these:

The Thames & Kosmos Fuel Cell Car & Experiment Kit provides a playful introduction to one of the most significant technologies of the early 21st Century. With this kit you can build a model car that actually runs on water!

First, add water and watch it separate into hydrogen and oxygen. Then, use those stored gases to power your vehicle across the floor. Now that we have your attention, roll up your sleeves and find out more through experiments and demonstrations you can do on your own, in a classroom or with friends.

Fuel cells are a promising means of producing energy in the future. Some fuel cells, such as this one, do not consume fossil fuels and therefore are considered environmentally friendly. Automobile manufacturers are already experimenting successfully with this technology and it is widely believed that fuel cells will power automobiles and many electronic devices, including laptops and cell phones, in the near future.

With this unique kit, you can build your own experimental reversible fuel cell car to learn more about this energy source. With more than 30 experiments and demonstrations, users will learn how a reversible fuel cell works to perform electrolysis as well as to create energy. The electricity required to activate electrolysis is created with a large solar cell included with the kit. During electrolysis, water is separated into hydrogen and oxygen and the resulting energy is stored as a gas. When needed, the gas is fed into the fuel cell, which then serves as the power source.

From: Thames & Kosmos

How can I calculate the real power of a panel?

To calculate the power and let it work nearly 100% we need to consider:

1. Intensity of solar radiation (sunshine). The highest value is obtained only in exceptional weather conditions and practically never in real situations.
2. Temperature of 25 ° C but we all know that in a day of exceptionally high sunshine for sure the temperature is above 25 ° C. Higher temperatures cause a decreasing of the performance of the panel.
3. Incidence of perpendicular sunlight.

How much energy produces a panel in one day?

To know the amount of energy produced daily we need to refer to the tables of sunshine, tabulations that indicate the monthly averages of sunshine for each geographical area;

For example, if your plant produces a maximum current, in full sun can get in 6A battery, then the power produced daily is: 6A x 5 (hours of sunshine) = 30Ah every day (on average) during the summer months and 6A x 2 = 12Ah in the winter months.

From: Solar car battery chargers

I've found this tool very useful to calculate the real solar power to use in our hydrogen cars.