Solar Photovoltaics: Pros and Cons

There is no perfect energy source. Each and every one has its own advantages and compromises. This series will explore the pros and cons of various energy sources.  Learn about other forms of energy generation here.

Solar PV is perhaps what most people think of first when they think of renewables (though we actually use more biomass). Solar PV can be used anywhere the sun shines as long as there is space available. Enough sunlight falls on the Earth in one hour, to meet the world’s energy demand for a year, if it could be collected. It is eminently scalable with installations ranging from a few kilowatts to the 48 megawatt Copper Mountain solar farm in Nevada. Utility scale solar capacity is quite small compared to the big boys, like the 8200 MW Kashiwazaki-Kariwa nuclear plant in Japan or the 5780 MW Taichung coal plant in China.

Solar presently contributes a very small share of our energy pie, around 1 percent, but it continues to grow at double-digit rates and is projected to triple from 2010-15 after growing almost ten-fold from 2003-2010.

It is also the subject of a great deal of research, so we should expect a number of breakthroughs coming down the pike, including things like nano-pillars to lower cost, concentrators to reduce the area required, and more efficient and powerful cells, to reduce both. Most solar PV systems today are either made from traditional silicon-based solar cells, or the newer thin-film technology.

Solar PV systems produce DC current, which can be used with DC appliances or converted to AC by means of an inverter. More and more of today’s electronics run on DC, which requires those little power supplies that plug into the wall which convert the AC to DC. This could be an opportunity in the future to power these devices directly from solar PV, eliminating the efficiency losses that occur when converting from DC to AC and then back again.

Let’s take a look at the solar PV pros and cons.

Pros

  • Clean energy. No combustion. No greenhouse gas emission from use.
  • Inexhaustible and abundant “fuel” supply
  • Available nearly everywhere
  • Well suited for distribution generation
  • Technology exists today and is rapidly improving
  • Generates electricity directly from sunlight
  • No moving parts required
  • Power generation is silent. No noise or pollution.
  • Little or no transmission required
  • Matches up well with air-conditioning need
  • Require minimal maintenance
  • Grants and incentives are sometimes available
  • Excess heat can be used for co-generation

Cons

  • Intermittent source. Not available at night or under clouds.
  • Relatively high cost, especially with storage
  • Requires inverter to produce AC current
  • Requires storage or grid connection for continuous round-the-clock use
  • Less available for heating demand (time of day and season)
  • Exotic materials required in many thin-film systems
  • Requires a relatively large amount of open space
  • Relatively low efficiency (around 17-40 percent)
  • Relatively low energy intensity ( ~8-12 m2/ kW)
  • Fragile materials
  • Possible aesthetic issues
  • Technology risk: a much better system might come out next year

Besides the relatively clear cut pros and cons of solar PV, there are also the transformative socio-economic impacts of moving from centralized to distributed power generation. There is clearly a technical advantage, since efficiency losses associated with long range transmission are eliminated, as are, possibly hundreds of miles of power lines that now crisscross the landscape. Lost would be certain economies of scale and centralized control. Distributed power generation is more resilient against large-scale blackouts as well as acts of terror, though it could mean a change in business models for today’s utilities. This is a trend that has been predicted by Jeremy Rifkin in his Third Industrial Revolution. After all, who wouldn’t want a house that produces its own power, rather than a house that is just a house?
***
To summarize:

***

What about other energy sources?

[Image credit: eastpole: Flickr Creative Commons]

RP Siegel, PE, is the President of Rain Mountain LLC. He is also the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Now available on Kindle.

Follow RP Siegel on Twitter.

RP Siegel

RP Siegel, author and inventor, shines a powerful light on numerous environmental and technological topics. His publications include business and technical articles as well as books. His third, co-authored with Roger Saillant, is Vapor Trails, an adventure novel that shows climate change from a human perspective. RP is a professional engineer - a prolific inventor with 52 patents and President of Rain Mountain LLC a an independent product development group. He is also active in his community of Rochester, NY. A regular contributor to Mechanical Engineering magazine, RP recently returned from Abu Dhabi where he traveled as the winner to the 2015 Sustainability Week blogging competition.. Follow @RPSiegel on Twitter. Contact: bobolink52@gmail.com