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Environment Solar energy is going to power the world much sooner than you think Solar electricity is growing rapidly, but can it really dominate the global energy system? Here is what it will take for us to power the planet on sunshine By Madeleine Cuff 23 October 2025 The future of solar is looking bright fuyu liu/Shutterstock Is solar power going to take over the world? The past few years have seen a frankly astounding acceleration in the rate of its deployment, with total generation capacity doubling between 2022 and 2024 to supply a full 7 per cent of the world’s electricity. Just how high can that figure go? The first six months of 2025 saw wind and solar together pass a historic milestone, generating more power than coal for the first time and making renewables the world’s leading source of electricity. The driving force behind this “crucial turning point” in the energy transition, as the UK-based think tank Ember described it, was the growth of solar. It accounted for 83 per cent of the total increase in the world’s electricity demand in 2025, Ember’s analysis indicates, and has been the largest source of new electricity globally for three years in a row. Solar’s secret weapon? How cheap it is. It is the world’s lowest-cost electricity, with the cost of installing a solar system dropping in price by 90 per cent over the past 15 years. “Right now, silicon panels themselves are the same cost as plywood,” says Sam Stranks at the University of Cambridge. In other words, we have a plentiful and cheap source of electricity that can be built quickly, almost anywhere in the world. Is it fanciful to imagine that solar could one day power everything? At the most fundamental level, the supply of solar energy to Earth is almost limitless. Even once you factor in the efficiency rates of modern solar panels, supplying all of the world’s energy needs with the sun’s power would require around 450,000 square kilometres of land, a 2021 report from the UK think tank Carbon Tracker estimated. That’s just 0.3 per cent of global land area. Kingsmill Bond, one of the report authors and now at Ember, says that, while there are “trade-offs” when it comes to land use – solar may compete with agriculture, for example – “for most countries, there is plenty of space to deploy these technologies”. A new generation of panels The question, then, is what is stopping solar power from taking over the global electricity supply entirely? The first issue is that of efficiency. Silicon photovoltaic panels, which make up the bulk of the global solar market, currently convert about 20 per cent of the sun’s energy into electricity. By comparison, hydropower plants convert 90 per cent of the potential energy into electricity, wind turbines about 50 per cent and fossil fuel plants 30 to 40 per cent. In real terms, this means you need many more solar panels to provide the same amount of power that you could harvest from other sources. That’s why solar firms and scientists are hard at work trying to unlock more efficiency gains from solar panels, in the hope that an efficiency boost will deliver a double win for solar: even lower system costs and less demand for land. However, crystalline silicon panels are nearing the limits of the efficiencies they can achieve, with best-in-class cells now at about 25 per cent efficiency. “The practical limit for crystalline silicon is probably about 28 per cent,” says Jenny Nelson at Imperial College London. Pushing efficiencies above that will require a shift to what is known as a tandem solar cell, which introduces a second semiconductor to increase the amount of energy a cell can extract from the solar spectrum. Tandem silicon-perovskite cells are seen as the most promising option, with a theoretical efficiency limit of about 50 per cent. Real-world tandem panels won’t achieve anything like that level of efficiency, but could reach 35 to 37 per cent efficiency, says Stranks. After years of research, the first tandem silicon-perovskite solar panels are just starting to enter commercial production, and they need to be tested by industry to see how long they maintain their performance under real-world conditions. But Stranks is optimistic about their potential. He estimates that in 10 years’ time, they will become the dominant technology on the market. “On the face of it, they wouldn’t actually look that different from the roof or on the street, but they are producing 50 per cent more power than today’s panels,” says Stranks. “It’s a big change.” Not only would greater efficiency cut costs even further, but it could also unlock new deployment opportunities, says Stranks. For example, high-efficiency panels could enable solar roofs on electric cars, allowing their batteries to charge during the day. The stored power could then either be used for transport or discharged to the home for use during the evening, he suggests. Solving storage Such innovation could help to untangle one of the other major issues with solar power – its fickleness. The sun, of course, doesn’t shine all the time. For countries in the “sun belt”, including India, Mexico and many African nations, this is less of a problem, as the sun shines almost all year round and batteries can be used to store excess energy during the day for use in the hours after dark. This solar-plus-storage set-up is becoming increasingly cost-effective, with the cost of lithium-ion batteries dropping 40 per cent in the past two years alone, according to BloombergNEF. “Ultimately, the only advantage that fossil fuels have over sunshine as a source for electricity is their storability,” says Bond. “And, suddenly, that storability issue has been solved for 90 per cent of the time by a single technology, which is the battery.” But for countries further north, where winter days are short and grey, it is a different story. “[Solar] is an unbelievably, amazingly good energy source, with zero pollution, rapid payback of energy investment – it just ticks every single box,” says Andrew Blakers at the Australian National University in Canberra, Australia. “Unless you live in northern Europe, north-east Asia or the north-east United States, where you have plenty of sun in summer and not much in winter, [solar] is simply the best.” For countries that suffer long, dark winters, wind power can step in to fill much of the gap, says Blakers. But energy storage solutions that can bank power for weeks or months at a time will also be needed. Such “interseasonal storage” is still in its infancy, with few solutions operating at commercial scale. But pumped hydro, hydrogen and compressed air storage could all provide an answer to this conundrum. Blakers’s prediction? “Batteries take care of the short term, pumped hydro takes care of the long term.” Political headaches If anything, efficiency and storage are the easy problems to solve. “I think the bottlenecks probably lie in politics, consistency in policy, regulation, vested interests of other industries,” says Nelson. The climate-sceptic Trump administration in the US is a case in point. Earlier this month, federal officials cancelled a huge proposed solar project in Nevada that would have been one of the largest schemes in the world, just the latest in a series of actions to curtail solar funding programmes and block projects. But Bond believes the transition to renewable power is now all but unstoppable given its economic advantages over traditional generation sources. “Incumbents can hold back the tide for solar in individual countries and individual projects and individual years,” he says. “The current Trump administration is doing its very best to slow down the current deployment of renewables. But all it really means is that they then fall behind in the global race to deploy superior technology.” Blakers agrees, adding that solar energy may be the only way to meet fast-growing power demand from AI data centres. “Even in the US, it’s difficult to see solar being turned off even by a determined federal government, because many states like it, and it’s by far the quickest way to get large amounts of energy,” he says. The other major bottleneck for clean energy is logistical. Existing electricity networks need to be rewired to cope with huge, fluctuating supplies of electricity coming from new areas. A more flexible grid, which can cope with surges in generation and even tweak power demand in response, will help to maximise the use of green power. But delivering these grids of the future costs money. In the UK alone, energy companies plan to spend £77 billion over the next five years refitting the transmission network to cope with the shift to wind and solar. In lower-income nations, where grid networks aren’t yet so comprehensive, countries can move more quickly to build renewable-friendly infrastructure from the get-go, allowing renewables to penetrate further into grid supply. The 10 so-called BRICS nations – Brazil, China, Egypt, Ethiopia, India, Indonesia, Iran, Russia, South Africa and the United Arab Emirates – now collectively account for more than half of the world’s electricity generation from solar, according to Ember. A wider challenge for countries is to electrify greater chunks of their energy demand, from heating to transport. Such progress is crucial to cut fossil fuel use in other parts of the global economy. As Nelson puts it: “If we want to decarbonise the planet, then we need to electrify first.” Here too, lower-income nations are racing ahead of higher-income ones. China’s share of electricity in final energy consumption hit 32 per cent in 2023, far outstripping the 24 per cent electrification rate of the US and richer European nations, says Ember. A solar future? Despite the success this year, the technical, logistical and political challenges outlined above may slow the rollout of solar in some countries in the short term. Earlier this month, the International Energy Agency predicted that renewable power will more than double by the end of the decade, but is set to fall short of an international goal to triple capacity by the same date. The agency said policy changes in the US and the challenges of integrating solar into grid systems were headwinds to the expansion in renewables capacity. But energy market experts are confident that, by mid-century and beyond, solar will dominate global energy supply. “By the end of this century, it is pretty clear that we will be getting all of our electricity from renewable sources, of which the vast majority will be solar,” says Bond, estimating that as much as 80 per cent of the world’s electricity supply will be generated by solar by 2100. Added to that, at least 80 per cent of the world’s total energy demand will be electrified, he expects. Roadblocks from politics, energy storage and infrastructure will all be cleared out of the way to usher in the green power revolution. “The human condition is to turn energy into stuff,” says Bond. “We use energy for everything. And now, suddenly, we found this cheap, universal energy source – of course, we are going to figure it out.”

Generally by the grade/classification of the land.

A GRP tray, which is the same material that fishponds are often made from will last decades. Probably because the environmental rules have changed a lot and it is easier to just buy credits and let some farmer turn his unproductive land into a weed patch.

All it is really saying is that between known limits, the total mass and the total flow will vary disproportionately. As the mass increases (more water soaked into the soil), then, until total saturation happens, the flow decreases. At total saturation, the mass is known (soil + plants + water) the flow will increase in proportion to the rainfall. If it freezes, which will probably happen when the weather is drier, ice can build up if it does rain. Heavy snowfall it probably the biggest structural risk (flat roofs are not as good as pitched roofs for distributed solid loads, why they have deeper joists). All in all, best avoided, or just create a small patch of greenery on it.

Think that should be price. Price is the nominal value is currency i.e. bag of 100 nails for £5. Cost includes the externalities i.e. pay someone to bang in nails after you have hit your thumb badly. So the price is just the nominal value of all the materials, cost includes materials and all the services to build a house, these days it also needs to include environmental charges.

I would have though that the first thing to know is by how much you need to reduce the light transmission to reduce the overheating risks. A random google though up this. Picking the first on the list got this. Silver 20 TECHNICAL SPECIFICATION Total Solar Energy Reduction 80% Solar Energy Reflected 50% Solar Energy Absorbed 39% Solar Energy Transmittance 11% Visible Light Transmittance 16% Visible Light Reflected 58% Ultraviolet Light Reflected 99% Shading Coefficient .28 Solar Heat Gain Coeff. (g Value) .24 Emissivity .70 Winter U-Factor (W/m² ºC) 2.82 Glare Reduction 82% I suspect that actual product would make a room quite gloomy, but there are other products. Maybe our resident glazing man @craig can throw some light (or paint) on it.

Darcy's Equation is all you need, probably.

When it is really cold, it is winter. The instantaneous power from the sun is quite low, maybe maxing out at 600 W/m². As the panels will only get about 20% efficient, that is 120 W/m². So while the voltage will be at maximum (PV modules are fixed voltage devices), the current is low, the MPPT will do it's thing and adjust the internal resistance to get the most out of the system. So should never become a problem. Panels are rated, and tested, at a standard temperature, irradiance and air mass. It is extremely rare in the UK to breach those limits. If you do get lucky, the inverter will 'clip' the power initially (the fan speeds up and dumps the excess power as thermal energy, and then will eventually disconnect if it cannot reduce the output voltage and current to the agreed limits (usually 253Vac and 16A per phase.)

Have we heard from @Garald recently, he probably knows about ladders.

The English make a simple job complicated.

Regarding the PV, Building Control may also want structural calculations i.e. wind and snow loadings. If a new build then the Structural Engineer should be able to supply the right paperwork.

Never looked into this, but have heard of it being done. You could split the system into two strings, with each string consisting of 6 panels paralleled up to another 6. That would halve the voltage while doubling the instantaneous current. That inverter can take up to 44Adc, but is designed to operate at 26Adc input. So it really comes down to what your panels can do, what is the maximum amps they are rated at?

It is, generally, not the ones that know we need to worry about. I work with some completely uneducated numptie, if they get away with something just once, that becomes policy, regardless of how often it has failed before or after.

You could look at single room dMVHR. When it comes to the heat recovery of the ventilation, you really need to know how airtight your property is. The only way to do that is to get it tested. If it not that air tight, a positive pressure ventilation system may be enough. There are lots of nuances when it comes to ventilation policy i.e. where are the air leaks, what do they leak into, fraction of overall losses...

I seem to remember that they do get taught it if they do a proper Level 3 apprenticeship. We were taught it on our Part P (limited scope) and that was specially designed for plumbers, PV installers, HVAC etc. Steico do this useful guide. Site_Guide_A6_online.pdf It is wrong that technicians, from other trades, should be making decisions about structural elements. We would not expect a painter (which has Level 3 qualifications) to be making changes to structures.

SMA are a bit iffy about people tinkering with their inverts. Is it still covered by warranty. Seem to remember they offered replacement once the old one is sent back. Call the local agent and see. That would fry it for sure, especially when written correctly, kW. But you mean kWh.

Should have painted it before foaming.

Do you hear that tapping sound, it is the hammering of the coffin nails.

Integral skin polyurethane foams do that. Used for making chair arm rests, and costing the steel hoop in car steering wheels. If you cut it open, you will find a 2 or 3mm thick skin. It is created by temperature difference between the injected liquids that react and foam, and the tooling temperature. With a bit of experimenting you can find the best temperature to heat the can up to get it to either skin on the contact surface or the air interface. Alternatively, and maybe easier, foam up with something strong enough, then coat the outside with non foaming PU. In effect, creating your own skin on outside. (Thinking while typing the above, paint the joint with non foaming PU, foam, then paint outside with non foaming)

Was a problem with honeycomb aluminium and composite plastic structures. Was fine for making the 'tub' of a racecar, but heat shielding was needed in the engine bay. Some of those impressive supercar fires on in YouTube are caused by heat induced delamination. Use with caution. There is a reason SpaceX use stainless steel for rocket bodies.

Will have to say the word sperm, so will get in trouble. Softwoods are gymnosperm, hard woods are angiosperms. Now it is early in the morning to be thinking about wood.

Often wondered about that. I did ask for my system to be completed flushed out at the 100k mile service (and it was). Think it is pink.

There are many answers. Can you temporarily bolt wheels to an axle and fit that at one end, or even bolt wheels to the side.

We have been discussing this here. Hoping to find answers as well.

@Marvin While I can see people's concerns about lack of space heating when the DHW is heating, I can't recall a time that people have actually had a problem. There is no reason that DHW cannot be heated in smaller time steps i.e. half hour here and there, this is what PV to DHW diverters do. One if the things I have tried to do at home is limit the maximum current that my house draws. So when the DHW is heating, I don't have the storage heaters recharging. This is purely a game I play as my supply, at 100A is not at risk. The other game is increasing the length of time that my house draws zero power (well less that 1 Wh). I think 3 hours is my record. Must have had something defrosting in the fridge. Putting those two games together means I can get a picture of how much energy needs to be stored, and how little needs to be delivered to keep the same living standards. Do you have monitoring equipment that logs at the Wh level, or are you using the smart meters half hour averages?