The solar component for a 10 watt system can be had for under $400 USD.

The Watt hour efficiency is the ratio of the amount of energy available during the discharge of an accumulator to the amount of energy put in during charge.

-9900

You should think of "watt" as a rate or speed ... it's the speed of using energy, but instead of

speed, it's called "power".

1 watt means that 1 joule of energy is being used every second.

1 watt-second means the amount of energy used in one second, when it's used at the rate of 1 watt.

In the last paragraph, we just said that this is 1 joule of energy.

"Kilowatt" is also a rate at which energy is used. It's 1,000 joules per second, or 1,000 watts.

Norway, Sweden, Denmark.