Groucho Marxism

The term solar power refers to the conversion of energy from sunlight into electricity. This can either be done directly using photovoltaic cells or indirectly using concentrated solar power. Photovoltaic cells convert light into electricity using semiconducting materials that exhibit the photovoltaic effect: a physical phenomenon whereby a material generates electric energy upon being exposed to light. This was initially solely used as a source of electricity for small and medium-sized applications, but is now being used for industrial electricity generation. Concentrated solar power, on the other hand, involves systems that collect solar heat for the generation of electric solar power, by using mirrors to concentrate a large area of sunlight toward a receiver.

According to the 2026 Global Electricity Review, solar power generated 9% of global electricity in 2025. This is encouraging but is still a relatively small proportion. It is well-known that geography affects solar energy potential because some places are sunnier than others. Land availability also has a significant effect on the potential for solar energy deployment. The obvious question then is: what percentage of our electricity could realistically be generated using solar power? Theoretically, the earth receives enough sunlight to supply 100% of global energy needs, but practical generation limits depend heavily on weather, availability of grid storage, and costs. As a result, expert opinion is divided on whether a fully solar-powered grid is possible or not.

Solar power contributed around 6% of the UK’s annual power generation in 2025, according to Ember, an independent global energy think tank. Whilst the sunniest parts of the UK receive much less solar radiation than the sunniest parts of Europe, solar radiation in the south is comparable with that of central European countries that generate more of their electricity from solar: the equivalent proportions for Belgium, the Netherlands, Luxembourg, and Germany were 15%, 21%, 30%, and 18%, respectively. Derry Newman, chief executive of the UK’s largest solar company, has pointed out that the UK’s “famously overcast weather does not make it an unsuitable place for solar power, as solar panels work on daylight, not necessarily direct sunlight.”

The UK’s total energy usage in 2025 was approximately 300 TWh, of which solar contributed around 18 TWh. According to the Solar Power UK, of the total solar capacity in the UK around 50% is accounted for by ground-mount solar farms, 30% by residential rooftop installations, and 20% by commercial rooftop installations. So we may assume that in 2025, ground-mount solar farms generated around 9 TWh, residential solar around 6 TWh, and commercial solar around 3 TWh. Approximately 6% of houses in the UK have solar panels and around 5% of commercial buildings in the UK have solar panels, according to figures from Sunsave and Solar Energy UK respectively. If these proportions were increased to 100% then rooftop solar power could in theory generate around half of the UK’s energy requirements.

In order for solar to generate all of the UK’s energy requirements the remaining 150 TWh would need to be generated by ground-mount solar farms. This would require scaling up the ground area covered by existing solar farms by a factor of 17. Solar farms currently cover roughly 0.07% of the total land area in the UK, according to a study by Lancaster University. Scaling this up by a factor of 17 would result in 1.2% of the UK’s land area being covered by solar panels. This would not be popular with many and is probably not feasible in practice. However it is worth noting that solar panels have been getting increasingly more efficient over time, and have almost doubled in efficiency since 2010. If this trend continued then we would be able to gradually reduce the land area devoted to solar farms.

Another way to view this is on the micro- rather than the macro-level. The obvious question to ask here is: what percentage of a building’s electricity can be generated using solar power? According to figures published by Meel Group, a standard residential or commercial solar panel setup typically supplies 30% to 65% of a building’s electricity use. With a solar battery storage system, that coverage can increase to about 80%. All of which raises the question of why we are not rushing to install solar panels on every building in the UK. The main reason is that installation of solar panels has been outsourced to the private sector, which means the cost of installation must be borne entirely by the owner of the building, and this is a cost that many simply can’t afford.

The same problem arises with other clean energy technologies such as heat pumps. Although installation of these technologies is often subsidized, they are rarely subsidized to the point that they are actually affordable. Thus we find ourselves in the bonkers situation where we have clean energy technology available that will help to mitigate the climate crisis and save people money on their bills, yet people are unable to install this technology as they cannot afford it. The government could easily run a mass heat pump or solar panel installation program if it wanted to. The reason it doesn’t do this is not lack of money but the prevailing neoliberal ideology which dictates that everything must be done by the private sector.