Photovoltaic Summer

When the sun shines and the wind blows, it is seen some areas can easily fulfil their potential energy. Renewable energy around the British Isles and other oceanic regions seems to be having a good year. When we compare the amount of electricity generated by the solar photovoltaic (PV) systems of different Solar Schools, we will often see varied results.

There are many reasons for this with one explanation being the intensity of light being absorbed by the PV cell is directly linked to the amount of electricity generated by the cell. In a solar generation system, this light is sunlight and its intensity changes throughout the day. These fluctuations vary based on the time of day, weather, latitude (or location) and the season. For example, during winter the generating daylight hours are shorter.

Germany is among the most advanced in getting down to building larger structures, on many brownfield sites, however the sun came out for many parts of Europe. While the short-term is immaterial for most purposes, if we can't boast about renewables in the summer, then consumers may think they can't produce the energy required.

Wind energy can now produce nearly 10,000MWh in the UK in a day, compared to the 16,000MWh that PV cells produced on one sunny day last week. That's from 450,000 solar roofs on individual houses, mainly. The German Republic managed 40% of its daily need (daytime hours only) on 7th July, while all of that UK effort managed a mere 6% on the same day.

Alan Simpson has been fact-finding on German credentials for the solar industry. In his opinion, "Germany is now "light years" ahead of the UK and benefitting. Within a decade, many German towns and cities could be substantially 'off-grid' and will be taking the grid system out of the hands of the private energy companies."

For the UK, the sunshine this year is a record July offering, although obviously the figures have yet to be finalized. Perhaps the south-facing PV cells they have will soon become more efficient, so that west or even east facing rays can be used to spread the capture throughout the day, just as Germany is planning west-facing installations. Several methods of tracking the sun have been applied in various locations. Electric builds many solar power plants in Europe, whose chief executive reports that they have parity in generation costs with conventional power stations. The difference is there are no emissions!

The seasons are governed by the tilt of the Earth's axis in space as it journeys around the Sun in a year. The tilt of the Earth also influences the effects of incoming solar energy on atmospheric and surface temperatures. And the tilt of the Earth influences the amount of sunlight that a location receives. At the equator, the amount of sunlight in a day is the same each day during the year.

At locations, further away from the equator, seasonal changes occur and a day's length will increase during the summer season and decrease during the winter season. When the South Pole of the Earth is tilted towards the Sun, this is our Summer. Six months later, when the South Pole is tilted away from the Sun, it's our Winter. In between these we have Autumn and Spring.

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