Making and maintaining solar panels will soon be cheaper than fossil fuels / Getty

Last comparable eclipse was in 1999, but much less power was generated using solar then

Friday's solar eclipse, the first since many countries made a concerted effort to switch to renewable energy, will pose a major challenge to Europe's power supplies.

This week's eclipse will be the most intense since 1999. Since then, countries' reliance on solar power has surged such that even a small change in the amount of sun over the morning of the eclipse could have huge effects on the amount of energy produced.

The effect of the challenge will vary widely,depending on the growth in the use of pholtovoltaic power. Germany, for instance, has turned to solar power hugely since the eclipse in 1999 whereas other countries such as those in Scandinavia have seen less of a change.

In 1999 ,only 0.1 per cent of the renewable energy supply came from solar. But now, 10.5 per cent of the green energy generated in Europe comes from photovoltaic plants.

Last month, the European Network of Transmission System Operators for Electricity, the organisation that makes sure that energy is distributed properly across Europe, said that it was preparing for challenges during Friday's eclipse.

Solar eclipses have happened before but with the increase of installed photovoltaic energy generation, the risk of an incident could be serious without appropriate countermeasures," the group said in a statement.

The eclipse will begin at around 8am on Friday, and run until about 11am.