How does a solar panel system work?
- Solar panels absorb sunlight with photovoltaic cells, creating direct current (DC) energy.
- Solar inverters convert the DC electricity into usable alternating current (AC) energy.
- AC energy flows through the home’s electrical panel and is distributed accordingly.
Solar energy is one of the most prevalent renewable energy sources available and California has some of the best solar potentials around the globe. Surprisingly transforming light into energy has been around for over a century and has only recently become mainstream as prices have significantly dropped and solar panel efficiency has gone up. Specifically, solar photovoltaic (PV) systems use sunlight particles, called photons, to knock electrons free from atoms to generate a flow of electricity. More broadly, the right sized system, in conjunction with net metering (or a battery) can cover your entire electricity usage.
This page will serve to give you an overview of solar components, the process and break down the solar industry terms into easily digestible bite-sized pieces of information. Delicious!
Components
Solar Panels
Solar panels are the physical components that contain the materials that convert the sun’s energy. There are two main ways of conversion creating two completely different type of panels: thermal and photovoltaic. Thermal panels capture the sun’s heat with a specific use case to heat water (think swimming pools) whereas PV panels convert sunlight into electricity. This makes PV panels clearly more practical for just about every situation (and everyone) which is why we will talk exclusively about them from here on out.
There are two main types of PV panels used today: polycrystalline and monocrystalline panels. The key differences between the two types are efficiency and cost. The monocrystalline panels are more efficient but also quite a bit more expensive to produce than polycrystalline panels. This typically gives the polycrystalline panels an edge to be installed more often despite the small decrease in efficiency.
Many other types of panels types are still developing such as thin-film solar cells and show promise but are still several years away from being ready for long-term real-world conditions and cost-effectiveness compared to current monocrystalline and polycrystalline panels.
Inverters
Inverters are an essential part of any solar panel system because these devices convert the direct current (DC) provided from the panels into alternating current (AC) used by all consumer electronics/appliances in our homes and businesses. The inverter has a crucial role in creating usable electricity and there are three main types of solar inverters that you will come across when adding a solar panel system to your home or business.
- String inverter (centralized inverter) – solar panel rows are on a “string” connecting to a centralized inverter where the conversion happens. String inverters are the most cost-effective of the options and are best for roofs with low to no shade. If there shade on one or more of the panels in a row than the entire row is forced to underperform because of their connection to each other.
- Micro-inverter – installed on or next to every single panel in order to completely maximize each panel’s production with shade only affecting the panel shaded. Micro-inverters are more expensive but are particularly effective for roofs that are going to see some shade. Other benefits include being able to monitor the production of each panel individually and creating a system that is easier to add on extra panels down the line if need be.
- Power optimizer – a hybrid of the micro-inverter and the string inverter. The power optimizer is installed at each panel but instead of converting the DC into AC directly, they “condition” the electricity before sending it to a centralized inverter minimizing the effects of shade. The power optimizers cost more than string inverters but less than micro inverters. They also have the ability to monitor individual panels.
Monitoring systems
Performance monitoring systems provide detailed information about how the system is performing throughout the day. It is able to measure the amount of electricity the system produces on an hourly basis along with monitoring the system for any performance issues that might present themselves. There are two possible types of monitoring systems that can be part of your whole solar panel system. It is common for systems to include a remote-monitoring system to transmit collected performance data through your home wifi (or a cellular connection) to the device manufacturer’s monitoring service which is accessible online. Some systems can include an on-site monitoring device on your property where you can see system performance data regardless of a wifi or cell connection.
Racking and Mounting System
Racking and mounting systems are used to attach the panel system to your roof or the ground, at an optimal angle for maximizing the amount of time in direct sunlight. Usually, this means facing south (or east/west if need be) at an angle between 30 and 45 degrees. There are two types of mounts that are used to attach a system. The first and most prevalent are fixed mounts and are completely stationary. These are less expensive and the only option if the panel system is going on your roof. The second type is a tracking mount and allows the panel system to move along a track in order to follow the sun as it moves throughout the day typically used in utility-scale projects which can maximize electricity production by 30% or more.
Other parts of a panel system
Smart Meter (bi-directional) – the device that is already installed on (most) homes by the utility company that is used to measure the incoming and outgoing electricity. This is essential for net metering policies where the utility company needs to keep track of your net electricity use for credits or charges.
Regulator – controls the voltage and direction of electricity for use with solar panel systems involving energy storage and EV chargers.
Main Service Panel (MSP) – every home’s energy hub that distributes electricity to other subpanels or various parts of the home through electrical sockets. Also known as a switchboard or circuit breaker panel.
Electrical Grid – the traditional delivery system of poles and wires the utility company manages that transmits electricity to your home from where it is created.
Solar Term Glossary
Alternating Current (AC) – the electric current that powers all our electronics and appliances.
Charge Controller – regulates the electricity that goes to a battery. (see Energy Storage)
Direct Current (DC) – the electric current produced by solar panels which must be converted into AC by an inverter.
Escalator – another term for rate increases used when financing a system through lease or PPA. (see Financing Options)
Generation Meter Adapter (GMA) – GMA’s are devices placed on meter sockets. They allow certain NEM customers to interconnect their renewable generating facilities to the supply side of their main panel breakers, without the need to modify their MSP.
Interconnection – Connecting energy production (i.e. solar panel system) to the electrical grid.
Kilowatts (kW) – power; the capacity to produce or consume electricity at any given moment.
Kilowatt Hours (kWh) – energy; the electricity produced or consumed over a period of time.
Monocrystalline – a type of PV panel that is made of single-crystal silicon wafers cut from a block of silicon.
Net Metering – policy allowing unused electricity produced by a solar panel system to be sent to the electrical grid for others to use while earning the owner credit. Credits from utility company can be applied later to receive electricity from the grid possibly during peak hours for additional savings or when unused can be reimbursed monetarily by the utility company (SCE for example). For more information on net metering see the page Utility Policy & Plans.
Photovoltaics (PV) – a type of solar panel that produces electricity from sunlight.
Polycrystalline – a type of PV panel that is made from melting multiple silicon fragments together.
PV Conversion Efficiency – the percentage of sunlight converted into usable electricity.
Solar Irradiance (insolation) – the amount of sunlight for a specific area usually measured in kW/m^2
Solar Renewable Energy Credit (SREC) – a policy, similar to net metering, regarding selling renewable energy to utility companies for a market dictated price. Only used in certain states which do not include California.
Thermal Panels – Panels where the energy is produced through heat from sunlight. Typically thicker panels connected to a pump used to heat swimming pool water.
Now that you know the basics of how solar works, check out the installation process and timeline.