Providing Solar Installations in the San Francisco Bay Area since 1989
Do you have questions before getting a solar power system for your property, such as what if my commercial building is in the San Francisco fog belt? Is my property suitable for a solar installation? If you have a question, we can answer it. If you don't see your question here, you can always contact us.
To determine whether a PV system is suitable for your property, we'd like to know several facts. (Please have the answers to the following questions when you contact Occidental about a site visit or an estimate)
1. Where type of property do you have?
2. What kind of roof do you have? (flat, pitched, hip, gable, other)
3. When was the last time your roof was refinished?
4. What kind of material is your roof constructed with? (tar and gravel, asphalt shingles, masonry, wood shakes, tile, other..)
5. What direction does your roof face?
6. Do you have any obstructions on your roof? (i.e.. chimney's, skylights, satellite or TV antennas)
7. Between 9AM and 3PM (peak sun hours), do you have anything around your residence or business like tall trees or buildings, that would block the sun, or would cast shadows on your roof?
8. How many kilowatt-hours do you use in a day / month? (This information is located on the 2nd or 3rd page of your electric bill.) Please have at least 12 months of utility information available so that we can accurately estimate your return on investment.
Do solar electric systems work in cold / cloudy climates? YES! Contrary to most people's intuition, photovoltaic panels work more efficiently at lower temperatures. This is because the solar cells in the panels are really electronic devices that generate electricity from light, not heat. In temperate climates, PV panels will generate less energy in the winter than in the summer, but this is due to the shorter days, not the cooler temperatures. PV panels also generate electricity in cloudy weather, although the current output decreases with decreased light intensity. PV panels do not need direct sun and can even generate 50-70% of their rated output under a bright overcast (good news for San Francisco!). A dark overcast corresponds to 5-10% of full sun intensity, so the output could be diminished proportionately.
You can find information on solar rebates available through the California Solar Initiative site.
For tax credits, visit California Solar Energy Industries Association - CALSEIA. Currently, the federal tax credit is 30% of the cost of the system.
Information on solar financing can be found at the Database of State Incentives for Renewable Energy website. Occidental Power is also looking into financing, such as home equity loans.
There are three main components of a solar electric system: the PV array, a DC to AC inverter, and a battery storage system. The PV array consists of one or more PV modules, which produce DC power when the sun is shining. The battery storage system contains a battery bank to collect and store DC power from the PV array, and a charge controller to prevent over-charging the batteries. An inverter transforms the DC power into AC power (identical to the utility power). PV systems also include various smaller components, such as disconnects, fuses, and ground fault protection as required by electrical codes. A number of our grid-tie installations do not include batteries, which reduces installation costs.
Solar electric (PV) panels contain silicon solar cells which produce electricity when exposed to light. When the solar cell(s) are wired to an external circuit and exposed to light, electrons can flow through the circuit, do useful work such as turn a motor or light a bulb, then return to the cell. Most photovoltaic panels are made of solar cells laminated in a plastic encapsulant between tempered glass and a plastic backskin. The most common type of solar cell is the crystalline solar cell. These cells are very fragile and must be encapsulated in a plastic substrate to protect them from fracture and moisture penetration. Solar modules are manufactured to be strong enough to withstand the most extreme weather conditions, including extreme heat and cold, high humidity, and even hail storms.
Most PV (Photovoltaic} modules are warranted for 20 years, but last indefinitely. Small decreases in power output are experienced over the life of the module, generally totaling less than 1% per year. No material is lost from the solar cells or module, nothing is emitted, and there are no moving parts! PV technology is certainly the most elegant and environmentally benign method of producing electricity.
Using typical borrowing costs and equipment life of 25 years, the life cycle cost of PV generated electricity generally ranges from $0.13-$.30 / kWh. Historically, this cost has limited most PV applications to areas which are not served by an existing utilities, or where high utility rates exist. For example, peak demand periods in the middle of the day have correspondingly high electric rates. This demand curve corresponds with peak production times for solar electric systems. PV systems can be used to trim this 'overbaseline' usage. When considering the cost effectiveness of PV systems in residential applications, we urge our clients to consider the following: PV systems provide power for home use over the lifetime of a house. By examining the life-cycle energy costs of a building (the total electrical consumption of a house over a time period) the cost effectiveness of a system can be examined. Nuclear, oil and coal generated electricity may seem inexpensive today, however utilities project that the cost will continue to increase. When other costs are factored in, nuclear, oil and coal generated electricity is not as inexpensive as it seems. For example, the cost of maintaining a military to defend oil reserves is not part of the cost per kWh on utility bills. Nor is the environmental impact of producing electricity with fossil fuels or radioactive materials. On a level playing field, solar and renewable energy is very competitive with traditional power production.
The net metering law in California allows residents to deliver clean and renewable solar power into the utility grid, and pay the utility only for the net difference of power consumed and power produced. Occidental Power designed and installed the first net metering system in San Francisco. This utility intertied system collects and adds power to the utility grid during the day to offset power use at night. The 1/2-kilowatt PV array produces DC power which is transformed into AC power by an inverter. The AC power, the same form as supplied by utilities, can be used by the residents when needed, or sold back to the utility under the net metering law. When the solar power is fed into the utility grid, the home's electrical meter runs backwards, effectively deducting kilowatt-hours from the resident's utility bill! With some energy efficiency improvements, the residents hope to maintain a net of zero consumed power. The lack of batteries in this system does not allow for back up power during a utility power failure, however the reduced cost and maintenance of such a system is well suited to an urban environment. During the day, the system produces excess electricity which is diverted through a bi-directional meter to the utility. The residents' utility bill reflects the net difference between power produced and power consumed. The goal is to reach a net of zero consumed power.