Solar Technology FAQs
- What is a solar electric or photovoltaic (PV) system and how does it work?
- Is my home or business a good place for a PV system?
- Do I have enough roof area?
- What size PV system do I need?
- How much electricity will a PV system produce?
- What is a kilowatt (kW)?
- What is a kilowatt-hour (kWh)?
- How much do solar systems cost?
- Can my city, homeowners association or neighbor prohibit me from installing solar on my roof?
- Are there cleaning and maintenance costs?
- Is a solar generating system difficult to operate?
- What happens during a power outage?
- Where can I get more information?
Q1. What is a solar electric or photovoltaic (PV) system and how does it work?
A. Solar electric or photovoltaic (PV) technology uses the sun’s energy to make electricity. When sunlight strikes an array of solar panels, electrons are freed by the interaction of sunlight with semiconductor materials (typically silicon). The electrons are collected to create electricity.
Direct current (DC) is the only type of current produced by solar cells. Appliances and machinery, however, operate on alternating current (AC), as supplied by your utility. The DC energy produced by the panels is fed into an inverter that transforms the DC power into AC power, which then feeds into the main electrical panel that powers your house or business.
A bi-directional utility meter is required to connect to the electrical panel. This meter is connected to your utility’s grid and is the means of delivering AC electricity both into and out of your home or facility.
Q2. Is my home or business a good place for a PV system?
A. First consider how much sunlight your property receives. Your property should have a clear, unobstructed access to the sun for most of the day, and throughout the year.
In California, the sun is in the southern half of the sky and produces more PV electricity than in the northern part. Because shading will reduce the amount of electricity your system will produce, PV panels should be installed in a location that is not significantly shaded by trees, chimneys or nearby structures.
The best orientation for a PV system is on a south-facing roof; roofs that face east or west may also be acceptable. Flat roofs can also work because the PV array can be mounted on frames tilting south; a PV array can also be mounted on the ground.
Q3. Do I have enough roof area?
A. The amount of roof space needed is based on the size, or generating capacity, of the system. Residential systems can vary in size from 50 square feet to 1,000 square feet. A rule of thumb is that a square foot of PV module area produces 10 watts of power in bright sunlight. For example, a 2,000-watt system would require about 200 square feet of roof area.
Q4. What size PV system do I need?
A. Several factors will influence the size of the system. The first step in determining the appropriate size is to consider your present electricity needs. A solar installer/contractor will be able to help you with this.
The average residential solar system size in SCE’s service territory is 5 kW, and the average non-residential solar system size is 262 kW. (These sizes are for CSI-funded systems.)
Q5. How much electricity will a PV system produce?
A. In California, a PV system will produce the most electricity in spring through fall when sunlight hours are the longest and the sun is positioned higher in the sky. A 1-kW system can produce from 1,400 kWh to 2,000 kWh per year depending on the location within the state. Generally, a PV system in the southern part of the state will produce more electricity than one in the northern part of California.
Q6. What is a kilowatt (kW)?
A. A kW is a basic unit of measure of real electric power or a rate of doing work. A kW is 1,000 watts.
Q7. What is a kilowatt-hour (kWh)?
A. A kWh is a basic unit of energy consumption. For example, ten 100W light bulbs burning for one hour will consume 1,000 watt-hours of electricity, or 1 kWh.
Q8. How much do solar systems cost?
A. The cost varies depending on many factors, including the system’s size, equipment options and labor costs. Typically, the installed costs are determined based on the size of the system’s output. The “cost per watt” ($/watt) is often used for comparing systems of different size.
It is difficult to predict how much an individual system will cost. However, it is not uncommon to see prices in the range of $7-$10 per watt. For example, a 1,000-watt system could cost $7,000 to $10,000.
The average cost of a residential solar system in SCE’s service territory is $47,714, and the average cost of a non-residential solar system is $2 million. (These amounts are for CSI-funded systems but do not include the incentives.)
Q9. Can my city, homeowners association or neighbor prohibit me from installing solar on my roof?
A. The California Solar Rights Act, enacted in 1978, limits the ability of covenants, conditions and restrictions (typically enforced by homeowners associations) and local governments to restrict solar installations. Get more information on the California Solar Rights Act.
Q10. Are there cleaning and maintenance costs?
A. PV output is significantly impacted by dirt accumulation. The frequency of cleaning depends on the location. For example, locations closer to freeways or industrial facilities, or in high-wind areas, are likely to accumulate dirt more frequently and should be cleaned more often.
Q11. Is a solar generating system difficult to operate?
A. No; it operates automatically, and shuts itself on and off automatically.
Q12. What happens during a power outage?
A. In case of a power outage, your solar electric system is designed to immediately shutdown for safety reasons. A grid-tied solar electric system does not provide power during outages unless it includes a battery storage system. Your power will be reinstated moments after grid power is restored; however, you will need to manually reset your solar system (inverter) back to service after your power is reinstated. – most have auto reset once power is restored.
Q13. Where can I get more information?
A. For additional information on “going solar,” visit www.sce.com/csi or www.gosolarcalifornia.gov.ca.
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