RESIDENTIAL SOLAR ENERGY PROS AND CONS


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Rising electricity rates and environmental considerations fuel a growing interest in solar photovoltaic (PV) technology. There are plenty resources on this subject on the web. Unfortunately, too many of them list only advantages of this technology and fail to explain all its drawbacks. In addition to this, it may not be easy for a homeowner to figure out an expected output in kilowatt-hours of a home solar system because of lack of practical "hard" information. As the result, people often have overly optimistic expectations for the PV systems. Well, not surprisingly, producing power from sunlight just like every other form of power generation has both advantages and disadvantages. The chart below will give you both sides of the story.





PV PROS

  • The fuel is obviously free.
  • The operation of photovoltaic systems does not produce any toxic-gas emissions, so-called greenhouse gases, or noise. For comparison, the conventional production of electricity from coal releases 1.5 pounds of carbon dioxide for each kilowatt-hour.
  • No moving parts are required unless you decided to install a solar tracker
  • The use of solar energy reduces our dependence on foreign oil.
  • Solar technology is versatile- it can be used in broad range of applications from small calculators to power plants.
  • Ability to generate electricity in remote locations that are not linked to a grid, as well as in space.
  • PV has an ability to provide backup power when the grid fails.
  • Periods of maximum sunlight are usually correlated with periods of maximum energy usage.

PV CONS

  • High capital cost, currently about $4,000 per kilowatt of peak power installed (before rebates and various incentives). Although there are companies who will install a system and lease it to you for $0 down, you would need to pay for it in fixed monthly installments regardless of how much energy the panels produce.
  • Solar energy requires large surface areas for useful amounts of electricity generation. Depending on the panel efficiency, you may need from 6 to 12 square meters (65 to 129 square feet) per kilowatt of peak capacity in non-concentrated light. At an average U.S. "insolation" of 4.5 sun-hours, you may get total of 0.37 to 0.75 kW-hours per sq.meter during an entire day. This would be under 16 to 32 watt per sq.m averaged over a 24-hour period. For more details see this analysis and a calculation of typical amount of PV-powered electricity.
  • PWM inverters inject high-frequency currents into home wiring, which acts as a large antenna. According to some studies, this electromagnetic radiation can cause negative health effects.
  • Because the intensity of sunlight varies with the time of day and weather conditions, an off-grid solar system requires either large storage batteries or to other supplemental energy sources.
  • Roof-top installations present fire hazard if there are trees nearby- dry leafs accumulated under the panels easily ignite by sparks. Also, the production of PV modules may use some hazardous materials (such as cadmium and lead). This can present health and safety hazards, if proper precautions during manufacturing, installation and recycling are not taken.
Conclusion. Currently, among sunlight applications, concentrated solar power as well as the thermal systems seem to be more economically feasible solutions than photovoltaic-based electricity. At present, non-concentrated photovoltaic generators are not quite cost competitive, although PV prices keep falling every year. While rebates and incentives can often offset more than half of the installation cost, for the society in general it may take decades to recover the net cost. Besides the cost, another major limitation of any time of solar energy is the energy storage issue.

Solar powered electricity of course is environmentally more friendly than electricity produced from coal and other fossil fuels. Solar energy also reduces our dependence on oil imports, although currently sunlight is used mainly in electricity generation, while oil-- mainly in transportation. That said, shale oil and gas extraction (fracking) enables the U.S. to be energy independent and it should keep a major role in our energy generation.