Solar Power

Question: How much electricity could the Sun really generate for us?


Bear with me, because I am about to quote Einstein:

E = MC2


Energy = Mass * Speed of Light Squared


Using this formula we can express energy as mass for easy visualisation as the numbers are so vast as to make them almost unintelligible.

The Sun’s rays which reach the Earth’s surface correspond in mass to approximately 173 metric tonnes of pure solar energy per day.

The entire human race uses approximately 20 kilograms of equivalent energy expressed as mass per day.

This means that the Sun provides 8,650 times our entire energy needs.

No internal combustion engines. No polluted city streets. No carbon emissions. No greenhouse gases. Just pure, clean, green* energy. Forever. Free.

For budding mathematicians here is the actual calculation:

F * (pi * Earth’s radius) 2 = 1.8 x 1017 Jules/s
(energy reaching the Earth’s surface every second where F = the Sun’s energy)

Mass captured as sunlight per second = 1.8 x 1017 / (3 x 10)2 kg/s = 2 kg/s
(the Sun’s energy expressed as mass per second reaching the Earth)

2kg/s= 173,000kg per day

173,000/20 = 8650
(proportion of the Sun’s energy reaching us compared to total human needs)


Now I don’t know about you, but I find this interesting, as we are constantly bombarded with information telling us that ‘renewable energy can form part of the energy mix, but cannot be the only solution to our energy requirements’. The next sentence is usually something along the lines of nuclear and fossil fuels being essential to humanity.

A second little-discussed factor is this: when we burn fossil fuels, we don’t just raise global temperatures through the release of greenhouse gasses, the heat from the combustion itself stays largely within the atmosphere.

But the atmosphere is really big, right? Surely it would take centuries to heat up?

Perhaps two and a half centuries of industrial revolution with 7.5 billion people and rising, all wanting cars, mobile phones, refrigerators, televisions, AC, most using power derived from the heat generating power stations including nuclear radiation.

There is only one sustainable future for mankind – to be entirely powered by renewable energy; and the cheapest, simplest and most convenient method is solar.

The renewables revolution will happen, it is both inevitable and necessary. It is not a question of if, but when?

*Full disclosure; the production of solar PV materials can be energy intensive and may use toxic chemicals and pollutants. However as more renewable energy is used in the manufacturing process which is purely a matter of critical mass within the grid and is fast approaching, and with a plethora of research projects replacing almost all non-environmentally friendly materials with green alternatives, truly zero polluting solar PV is about to arrive.

What is Solar Energy?

Solar energy is generally discussed in terms of thermal or electric, or a combination of both.

This seems obvious – the Sun is hot, it heats things up. But there is more to it than that. Clever use of the Sun’s heat has been employed throughout human history and is an invaluable source of energy for us today.

Passive Heat is the concept of quietly absorbing the Sun’s rays and then naturally releasing that energy in directed ways.

A practical example of this is a greenhouse through which vents can direct captured heat to adjacent areas, or erecting a thick dark exterior wall to a house which can absorb heat during the day and release it into the home at night via natural convection.

Swimming pools can be designed to circulate warm water on the surface with cooler temperatures at lower depths either with a ‘passive’ gravity system or using ‘active’ electrical motors powered by solar PV.

Further efficiency can be gained linking a solar powered heat exchanger which uses very little energy recycling hot or cold air/water/medium to exponentially increase or decrease temperature.

A good example of this is a ground source heat pump, in which pipes are buried underground where temperatures are constant, and water is slowly pumped around the system being cooled and warmed in turn depending on whether the ambient air is warmer or cooler than the ground.

The difference in temperature is then exploited and recycled in a heat exchanger for appropriate use. A small seemingly insignificant difference of a few degrees when processed through a heat exchanger can boil water or fill a hot bath, or even cool air conditioning in ‘off-grid’ housing for very little cost other than installation and maintenance of the system itself.

Photovoltaic Electricity or ‘Solar PV’ Photovoltaic cells generate electricity using the Sun’s rays to stimulate specific materials which then release electrons to be channeled into power grids or batteries.

Traditionally dark glass-like structures, increasingly scientists are now able to create new and innovative solar PV materials. We can now construct solar PV pavements and roads, transparent solar PV glass, and fascinatingly solar PV threads capable of being weaved into garments.

Solar PV clothes! Imagine when needing to charge a mobile phone, simply placing it into your pocket or handbag and going for a walk, and hey presto, fully charged!
The future’s so bright, I gotta wear shades…

Concentrated Solar Thermal Power or ‘Solar Electricity’
This is not to be confused with solar PV.

Solar electricity uses heat to generate electricity through specially designed machinery. Usually, the Sun’s rays are focussed by large parabolic mirrors into a concentrated area which heats boilers containing a medium (e.g. water, oil, salt) which in turn drives electricity-generating turbines.  This is much more mechanically intensive than solar PV, with higher costs requiring more maintenance. However, there are some advantages.

For example when the extreme temperatures are used to melt salt, liquid salt can store enough heat to power turbines for several days, effectively turning the Sun’s energy into a liquid salt battery.

Wots Hot®Energy believes passionately in the ability of mankind to power its entire needs, domestic and industrial with renewable energy.

Our Eco-House designs incorporate solar technology as standard, at an affordable price.

Our optional extras enable truly ‘off-grid’ housing solutions.

Contact Wots Hot®Energy here to discuss all your renewable energy needs.