Among sources of renewable energy, hydroelectric plants have the advantages of being long-lived—many existing plants have operated for more than 100 years. Also, hydroelectric plants are clean and have few emissions. Criticisms directed at large-scale hydroelectric plants include: dislocation of people living where the reservoirs are planned, and release of significant amounts of carbon dioxide during construction and flooding of the reservoir.[16]
Green-e is a voluntary certification program for renewable electricity products. The Green-e program establishes consumer protection and environmental standards for electricity products, and verifies that these products meet the standards. The Green-e logo certifies that at least half the power supplied is from renewable sources. Many products will carry the Green-e logo, and the best way to find the most environmentally sensitive providers is by doing some comparison research. To find out which Green-e certified products are available in your state, visit Green-e's electric choices page. Questions about particular providers can be directed to the Center for Resources Solutions, which administers the Green-e program, at (415) 561-2100.

A: A residential solar PV system can cost anywhere from $25,000 to $35,000, on average. Because of the high cost, a power purchase agreement (PPA), loan, or lease are popular options for financing a solar PV system. Naturally, there are benefits and drawbacks with each option. We won’t cover them in detail here, but you can learn more in our article “Financing Options for Solar Power Explained.”
As the cost of solar electricity has fallen, the number of grid-connected solar PV systems has grown into the millions and utility-scale solar power stations with hundreds of megawatts are being built. Solar PV is rapidly becoming an inexpensive, low-carbon technology to harness renewable energy from the Sun. The current largest photovoltaic power station in the world is the 850 MW Longyangxia Dam Solar Park, in Qinghai, China.
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