Depending on what exactly you are asking, probably about portable solar charger. It depends on what wattage your mobile device needs. Most cell phones are 5 watts, so you will a solar charger in that wattage level. You can also get one that is lower, however the charge time will be longer.
Also, be sure that you purchase a solar charger that has a built in battery pack that way you can rely on that when the sun is not out or during the night.
Depends on the engine... need to be more specific.
You need to use a blocking diode wired in series to prevent battery discharge via the solar panel at times of no sunlight, eg nighttime.
3 or 4 residential size solar panels.
we need solar power because it will save us lots of energy
The answer here would have to depend on the size of said city
You look at the job you need to do, ie, how many volts and amps, or volts and watts, that you need. Then you look in the catalogs for a solar cell or solar cell array to produce that much power.
You can buy ready-made solar panels fitted with connectors for mobile phones. Simply plug it into the handset, and stick the solar where it will get most daylight. (usually a window). The panel generates DC power, which will charge the phone for free !
Read the manufacturer's instructions. The unit is used to charge other devices using the sun. The unit itself doesn't hold a charge. How long it takes to charge other devices depends on what you're charging. This article offers a comprehensive overview and explains how to calculate the time various devices take to charge with a solar-power charger http://www.12voltsolarpanels.net/12-volt-solar-powered-battery-chargers A solar battery charger does not take a charge, hold it and then spend it to charge other devices. The solar battery charger is connected to the device and uses solar energy to re-charge the device, as opposed to charging its own self first. How long it takes the charger to charge another device depends on the voltage of the device.
Only Beats Wireless and Beats Studio Wireless heapdhones need a charger, and that's because since they don't plug into a device to play the music, they need another source for power to power the headphones. Hence, they have a built in battery that needes a charger to be charged.
If there is no light on an Enercell Battery Charger, it typically indicates that the charger is not receiving power or is malfunctioning. This could be due to an unplugged power source, a faulty power outlet, or an internal issue with the charger itself. Ensure that the charger is properly connected and try a different outlet to troubleshoot the issue. If the problem persists, the charger may need to be examined or replaced.
A website called whole solar has all the information you need to know about residential solar power systems. They have complete information about switching to a solar powered home and tell the cost of it and much more.
Although a cell phone charger is necessary to keep the battery in your phone full, you might wonder how many you actually need. Of course you need your standard charger, ideally left plugged in by your bed to charge each night. You might also want to invest in a car charger that can recharge your phone as you commute to and from work, or a solar charger than can work even when you don't have electricity.