3,850 zettajoules, a figure with 22 zeroes in it—that’s how much solar radiation our planet receives from our sun in a year.

To get a sense of how much potential energy that number represents, consider that in just one hour, the shining of the sun unleashes enough power to supply the sum of humanity’s global energy needs for an entire year. And with our current level of solar technology, we would only need about 0.3% of the earth’s land surface to harness that energy.

solar land area

This map shows the natural distribution of solar energy across the world. Just the solar areas covered by black discs would be sufficient to meet the world's primary energy demand. (Photo credit: Wikipedia)

Solar power clearly holds big promise, and it is currently the most competitive renewable energy on the market. Given the numerous advantages of solar energy, the industry is preparing to make scalable contributions to stressed electrical grids in the United States and beyond. But there are disadvantages of solar energy, too, and significant limitations remain.

solar power tower

The Solucar PS10 is the world's first tower-based commercial solar thermal power plant.

Cost is still perhaps the biggest disadvantage of solar energy. So far, solar successes have been heavily dependent on government subsidies to help reduce bottom line costs, but rapid innovation is bringing change. Emerging technologies, from nanowires to fuel cells, are positioning solar as the next big player on the grid. There will likely be big changes in the following years as new materials and designs come online, enhancing our ability to distribute sun-derived power in an intelligent and efficient fashion.

Let’s take a look at the current state, growth over time, and future potential for solar power as a major supplier of our collective energy needs. We’ll focus on solar energy advantages and disadvantages in terms of the environment, reliability, efficiency and economic cost.


When it comes to the environment, solar power makes a lot of sense. It results in minimal pollution - about 90% less than conventional fossil fuels. Sunshine is endlessly renewable, and more often than not solar installation components are recyclable. It is also widely available around the world.

Our current energy consumption, which depends mainly on raw fossil fuels like coal and oil, is associated with chronic water and air pollution, impending “peak” supplies, and aggravating global warming.

The advantages of solar energy are clearest concerning the environment and public health. 100% renewable solar power presents a tremendous opportunity to turn away from an economy based on some of the world’s dirtiest resources. It is arguably the renewable resource best positioned to take on this role in the broader mix.


Nellis solar power plant

Nellis Solar Power Plant in Nevada, USA. This 140 acre installation provides 14MW of power to the nearby air force base. (Photo credit: Wikipedia)

Is solar power reliable? One of the key disadvantages of solar energy is its “intermittent” nature. That means solar radiation is nil at nighttime, and weak on overcast days. This trait makes solar currently inadequate for meeting base load demand—the real meat-and-potatoes wattage needed to power society.

In the United States, the Department of Energy (DOE) is proactively pushing exactly that flavor of innovation through Stanford’s SLAC National Accelerator Laboratory in Menlo Park, California. Here, the DOE is funding promising research into a new kind of battery.

Reportedly, it’s cheap and durable enough to store solar and wind on the grid for large scale use. The battery, which uses chemical storage comparable to a reversible fuel cell, could equip electrical grids with renewable storage capacity on a revolutionary new scale.

Stanford’s new battery, hooked up to a grid, could theoretically conserve excess power from off-peak periods and conveniently discharge it during demand spikes. An adequate battery would enable a smooth, direct connection between demand and load. It would be a huge boon for the solar industry. This kind of storage capacity is a necessary component for any major grid-supplying energy source.


Efficiency ratings are another sticking point associated with today’s solar technologies. They are somewhat limited in terms of how well they are able to maximize electricity conversion while minimizing light lost as waste heat. According to Science Daily, most commercial panels today are no more than 25% efficient, with an average hovering between 11% and 15%.

These limits are not set in stone; what was once considered an absolute cap on efficiency is now negotiable, and the latest gadgets show solar conversion rates of up to 44%. While researchers will no doubt find more ways to optimize solar efficiency, the real test hinges on the cost of developing the means. That is, any solution must resolve efficiency gaps in a cost-effective and scalable fashion.

Efficiency is a key dimension of renewable energy; inefficiencies translate into waste and ecological harm. Solar systems yield 100 times more power over their operational life than either nuclear or fossil fuels. So, the good news is increased solar usage will improve the overall efficiency of the energy economy, even with existing technology. In the long run, solar represents a move towards less overall waste.

Economic Costs

Is solar power affordable or expensive? The answer is not straightforward; it depends on numerous factors. There are, however, some key trends to note.

Solar startup costs are high, usually requiring a sizable initial investment which recoups itself over a predictable time frame. All else being equal, larger installations benefit from a lower cost-per-watt. In the long run, we are looking at a potentially inexpensive, scalable way of powering up which pays for itself many times over.

But we are not there yet. Much of the solar market’s presence is backed by government subsidies that help keep costs down, including a 30% federal tax credit in the U.S. This support has given the sun’s rays a foot in the door, but markets are unpredictable and a lot could happen in a very short time.

Nevertheless, the consistent trend since the 1980s is ever-cheaper sun power. The cost-per-watt has fallen steeply over the last ten years in particular, and this pattern is likely to continue for the foreseeable future.

What’s next for solar energy?

Solar energy pros and cons are likely to shift under different conditions. Look for cost-effective financing to link up with scalable new storage and efficiency technologies. Resolution of solar power’s disadvantages in the areas of efficiency, startup costs, and reliability would be a strong signal of the sun’s readiness to take on the bigger, dirtier power players.

If you enjoyed this look at solar energy pros and cons, you should check out this list of interesting facts about solar energy.