Solar Photovoltaic (Solar PV)

Solar photovoltaic (PV) panels convert the sun's energy into electricity. Solar PV can work in almost any part of the world, as long as the site is not shaded. Multiple technologies exist, each with their own set of pluses and minuses.

General Information

• Photovoltaic arrays create useful energy when photons from the sun's rays strike and energize electrons in the photo cells. These cells are grouped together to form arrays, which are connected to each other and to a larger system that takes the energy produced and turns it into useful electricity compatible with your existing electric service.
• Many companies are attracted to solar arrays as a relatively easy way to demonstrate their environmental commitment. We strongly caution against looking at solar PV before addressing energy efficiency measures. Introducing a powerful renewable energy source into your facility when it's not energy fit is like putting high-octane fuel into a car that sorely needs a tune up.
• The cost per kWh of energy produced by solar PV systems sometimes prevents companies from moving forward with installation. However, technology innovations, manufacturing improvements, and innovative financing mechanisms like power purchase agreements (PPAs) are helping to overcome these hurdles.

Site Considerations

• Do you have a southern exposure? Whether the system is ground, pole or roof mounted, you will get the most production from an array that faces true south. In the Boston area, that's about -15° from magnetic south or 165° on a standard compass. The further you are from south, the lower your production will be.
• Is the roof shade-free all day long? A small amount of shading on even one module can have a tremendous negative effect on production of the entire array. Be sure to consider nearby trees, buildings, telephone poles, telephone wires, etc.
• How much productive roof space is available? It is common to use a 3:1 ratio for calculating shading from rooftop obstructions.
• Clarify your objectives. How much electricity do you want to generate? Is it important that you fix your energy costs? Reduce GHG emissions? Gain some energy independence? And what are you willing to spend?

Typical Costs

• Currently, solar arrays average between $5.00-$6.00 per Watt installed before rebates and tax credits.
• Federal law allows a tax credit equal to 30% of the installed system cost plus an accelerated depreciation schedule through 2016.
• To look up local, state and federal incentives, go to http://www.dsireusa.org/
• Maintenance costs are generally low.

RPM can help determine if a solar PV system is the right choice for your site. We can help you understand the costs and benefits of these systems relative to other possible efficiency or renewable projects. And, if it is a cost-effective solution, help with project development, choosing installers, and financing (PPAs, for example).

Remember: Efficiency first. Renewables second.

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