Solar Basics
- What is solar electricity?
- Basic PV terminology
- What is a watt?
- What is a kilowatt-hour?
- How does solar PV work?
System Design
- What size system should I install on my home?
- How efficient are photovoltaic modules?
- Where should I put my panels?
- What are the components of my system?
- Do solar panels and inverters come with a warranty?
- Should my contract include a workmanship warranty?
- Where can I find a contractor?
- What is the typical solar installation timeline?
System Costs & Incentives
Net Metering
Solar Basics
- What is Solar Electricity?
Photovoltaic (PV): photo = light, voltaic = produces voltage
Photovoltaic (PV) systems, also referred to as solar electric systems, convert sunlight directly into usable electricity in your home or business using semiconductor technology. Sunlight strikes the PV cells and causes the electrons to flow, creating an electrical current (photovoltaic effect).
- Basic PV Terminology
- DC: Direct current (produced by solar panels)
- AC: Alternating current (used in homes, business and industry)
- Efficiency: Measure of how much of the sunlight is converted to electricity (%)
- Capacity: Total amount of power that a system produces (also referred to as system size)
- Watt (W): Basic unit of power
- Kilowatt (kW): A unit of electrical power equal to 1,000 watts (most common solar system measurement)
- Kilowatt-hour (kWh): Basic unit of energy equal to the use of 1,000 watts of electricity for one full hour (basic unit of electrical usage billing)
- What is a watt?
- What is a kilowatt-hour?
The basic unit of energy: Energy = Power x Time.
Example: If ten 100-watt lightbulbs are left on for one hour, the energy consumed is 1 kWh (100 w x 10 = 1 kWh).
- How does solar PV work?
Photovoltaic (PV) systems convert light directly into electricity using semiconductor technology.
- Individual photovoltaic (PV) cells are connected to panels. Solar panels convert sunlight into direct current (DC) electricity.
- An inverter converts direct current (DC) into alternating current (AC) for electricity in the home.
- The utility meter records the net amount of energy generated through the PV system. When you’re creating more electricity than you’re using, your meter will "spin backward" and the excess electricity is sent to the electric grid. This helps to offset the cost of your electricity usage at night or on cloudy days when your system is not producing electricity.
System Design
- What size system should I install on my home?
Every site is different and the needs of the system owner vary. System size depends on several factors, including how much electricity (kWh) is consumed on-site, the orientation and tilt of the system, the available space and financial considerations.
Remember that you do not have to offset 100% of the consumption of your home or business. Offsetting any portion can be beneficial and a good way to get started with solar.
Always check with a licensed installer or contractor to determine the true optimal size of your system for the portion of your consumption that you wish to offset with solar.
- How efficient are photovoltaic modules?
Photovoltaic panel efficiencies range from 5% for some thin-film technologies up to 22% for single crystalline (rigid) technologies. These percentages refer to the conversion efficiency, or the percentage of sunlight that is converted directly into electricity. Conversion efficiency is a critical issue when space is limited – more efficient panels require less space to produce the desired amount of electricity.
- Where should I put my panels?
PV panels are typically installed on your roof but also can be mounted on the ground. Speak with your contractor about where on your property will yield the highest production. Typically, the ideal direction to have your panels face is south or west.
- What are the components of my system?
This is a list of components that may be included in your PV system.
- Solar panels/modules – The tools to collect the sun’s power and produce direct current (DC) power.
- Inverter – Converts DC power into alternating current (AC) power, which we use in our homes. There are two types of inverters: central and micro.
- Service/utility meter – This meter is a bidirectional smart meter that can keep track of any excess kWh production that you may send back to the grid.
- Kilowatt-hour meter – This meter keeps track of the kilowatt-hours your system has produced since the system was turned on. Note: Not all systems have a kilowatt-hour meter installed.
- AC disconnect - This is a device that the utility can use to turn off your PV system in an emergency or service situation. Note: Not all systems have an AC disconnect.
- Conduit – Conduit is the housing for your PV system’s wiring. Conduit is usually rigid piping such as EMT (electrical metallic tubing), flexible aluminum or PVC (polyvinyl chloride).
- Do solar panels and inverters come with a warranty?
PV panels come with a 25-year production warranty. A central inverter comes with a 10-year warranty, while microinverters come with a 25-year warranty. Most central inverter manufacturers offer a supplementary 10-year extended warranty at an additional cost.
- Should my contract include a workmanship warranty?
CSE advises receiving a 10-year warranty on workmanship. This is to protect against defects and undue degradation of electrical generation output.
- Where can I find a contractor?
The best way to find a reliable contractor is to ask friends, family, neighbors or co-workers who have had solar PV installed.
For solar installers near you visit Go Solar California.
- What is the typical solar installation timeline?
Your project will need a building or electrical permit from the city or county building and safety department before you can legally begin installation. Once you obtain the required permits, a typical residential installation takes as few as one to three days to complete. Typically, a minimum of two installers are on-site during an installation, but there can be more depending on the size and scope of an individual project. Some steps in the installation process can be completed simultaneously and most will be taken care of by your contractor.
Once your system is installed, the city or county will inspect it. After your new system passes this initial inspection, your local utility also may inspect the system to ensure it is interconnected to the electrical grid properly and meets all safety requirements. Be sure to keep your system off until you receive official permission from your utility to begin operation.
Steps Role 1. Research contractors and compare bids* Customer 2. Design system (site visit and usage evaluation to determine size) Contractor 3. Sign contract** Customer 4. Apply for building permit with appropriate city or county Contractor 5. Install the solar PV system Contractor 6. Apply for interconnection; submit application to your utility Contractor 7. City/county on-site system inspection; submit approval to utility City/County 8. Utility on-site meter inspection*** Utility 9. Turn system on upon written approval from utility Contractor 10. Receive first post installation utility bill under net energy metering Customer *Obtain homeowners association (HOA) approval, as needed, upon receipt of bids and prior to signing the contract.
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**Discuss and clarify roles with your contractor before finalizing the contract to ensure you understand who is responsible for each step in the process.
***On-site inspection may be waived by utility if they have instated a fast-track process and received all required documentation.
Sytem Costs & Incentives
- How much do photovoltaic systems cost?
The price of a photovoltaic system is determined based on a number of factors, including system components and configuration, the difficulty of installation and available incentives. The current average installed cost ($)/watt for a residential solar electric system is between $3-$5/watt.
- What are the current state and federal incentives?
A one-time federal investment tax credit (ITC) is available for residential solar PV systems. The credit is based on a percentage of the total system cost. If the system is placed in service before Dec. 31, 2019, a credit of 30 percent of the total system cost is available. After Jan. 1, 2020, the tax credit will start to decline.
Placed in Service Tax Credit Percentage By 12/31/2019 30% 1/1/2020 - 12/31/2020 26% 1/1/2021 - 12/31/2021 22% Note: The homeowner must have the tax appetite to utilize the credit, but it may be carried forward if not completely usable in the installation tax year.
Depending on your local utility, there may be solar rebates available. Typically, they are based on the size of the system installed. For more information on incentives, visit DSIRE.
Net Metering
- What is net metering?
This program is for customers who generate electricity by solar PV, wind, or other eligible generating systems. If your system produces more energy than you use, you can earn bill credits for the excess power your system sends into the utility electric grid. You can later use that credit to cover cost of the power you may need from the utility at times when your generating system doesn't fully meet your electricity needs.
- What are the benefits of Net Metering?
You can receive up to full retail value for the production of your system
Net metering allows you to use the power that your solar electric system generates to offset any consumption beyond what your system produces. The utility acts as a bank to store your excess production, then allowing you access to that power to offset your own consumption. Check your local utility net metering rules to understand if there are additional fees or charges included in the service.You can receive wholesale value for the annual excess production of your system
If your solar electric system produces more kWh than you consumed annually, your utility may purchase excess energy from you at a wholesale rate.No need to store excess solar energy onsite
Due to the fact that you get credit for your excess power generation, it is not necessary to install a battery storage system. Through net metering, the utility acts as your "battery bank" and provides you credits for those solar kWh's. However, some may still decide to install a storage system to offset time-of-use rates, demand charges, or for a battery backup.
