Tools : Answers to Frequently Asked Questions

How does solar electricity actually work?
Most solar panels are made from silicon -- a benign material that is the second most common substance on earth. A panel consists of a layer of silicon with wires imbedded in it, mounted on a substrate, encased in tempered glass and a metal frame. When exposed to light, the silicon generates current. The more light there is, the more current gets generated. Solar panels have no moving parts, require virtually no maintenance, make no noise, and produce electricity during the time of day when it is both most expensive and most needed. Photovoltaic technology is remarkably durable and there have been panels in continuous operation for as long as 40 years. The industry standard warranty for solar electric panels is 20 to 25 years.

Is solar electric technology really ready for large-scale, urban applications?
Yes. While solar energy has its roots in remote off-grid locations, its future is in grid-connected applications. The efficiency and reliability of the panels and inverters has increased substantially as the costs have continued to decline. 

How can taxpayers be assured that a solar revenue bond won't affect their pocketbooks?
Let's look at three facts. First, as weather data reveals, the amount of annual sunlight a city receives turns out to be very predictable so one can determine with great accuracy how much solar electricity could be produced in a given location. Second, the track record for reliability in photovoltaic technology is excellent. We can project with confidence the amount of electricity a solar array will produce over time. Third, energy efficiency has made colossal strides in the last decade and most large public buildings in the country today now have the potential for 25-50% savings by upgrading to newer and better energy systems. These savings are instrumental is making the solar bond model work. By far the most variable factor in the equation is the market price of electricity, which has proven to be volatile over time.

What is the exact payback period of the revenue bond?
In San Francisco, the bonds will be paid back over 25 years. However, the exact payback period for a solar revenue bond will be different for each city depending on a number of factors:

- how much annual sunlight there is
- how much energy efficiency work can be done
- what the cost of electricity is expected to be
- what subsidies are available
- what the bond rating of the city is
- how much more the price of solar energy will fall over the implementation period

If this is such a good idea, why aren't more cities doing it?
Solar power has been around a long time, but it has been expensive. As the costs have come down and the technology has improved, more and more cities are showing interest in building on San Francisco's success.

 

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