The challenge of harnessing the sun's energy
The sun is everywhere. So why isn't solar power everywhere? Passive solar power is. It lights our rooms when we open the blinds in the morning and it melts the snow on a sunny day. But converting solar energy into electricity that can be used to power appliances or generate heat has traditionally required overcoming challenges, including:
- High system costs
- Limited solar cell efficiencies
- Grid connection issues
- Building code acceptance
- Unattractive panels
- Time consuming installations
So just how much sunlight is enough?
| Did you know... • About one-fifth of the sunlight reaching Earth is absorbed by the atmosphere. • The Arctic Circle receives 230 more hours of sunlight than the Equator. • Fossil fuels are actually stored solar energy that has been concentrated by geologic processes. • Wind, wave, tidal and biomass energy are indirectly driven by the sun. |
The amount of electricity generated from solar power is directly affected by the amount of sunlight falling on each geographic location. This is known as "insolation."
In general, areas closer to the Equator have a higher insolation value than those farther away, and insolation values may change with the seasons, as the rotational axis of the Earth shifts. However, insolation is also affected by the time of day, cloud cover and air pollution.
But don't think that solar power is only viable in sunny areas close to the Equator. Germany is currently the world's second largest generator of photovoltaic power, yet its insolation values are equivalent to those of Alaska.