Solar Education

How do solar panels generate electricity for your home?

The folks at Energy Sage have some amazing content around solar education and we have referenced a lot of their work here for your benefit. You can check them out if you want to go even deeper. Enjoy the brief introduction into how solar panels can power your home.

 

In 1954, scientists at Bell Telephone discovered that silicon, an element found in sand, created an electric charge when it was exposed to sunlight. This discovery led to the development of solar cells that captured the sun’s energy and turned it into electricity. Since then, the technology has evolved, and solar power systems now provide incredibly attractive financial benefits for homeowners, businesses and non-profits across the United States.

Thanks to solar panels, we have access to an inexhaustible source of power – the sun. Throughout the day, the cells on your solar panels absorb the energy from sunlight. Circuits within the cells collect that energy and turn it into direct current (DC) electricity. The DC electricity is passed through a device called an inverter to convert it to the alternating current (AC) electricity used by most homes and businesses. You can use that electricity in your home, store it with a solar battery, or send it back to the grid.

Solar panel system components

  1. Solar photovoltaic panels (“solar panels”)
  2. Inverters
  3. Racking and mounting systems
  4. Batteries
  5. Performance monitoring systems

Solar Panels

Solar panels collect and convert the sun’s energy into electricity. They are a key component of a solar panel system. Most commonly available panels today are either poly-crystalline or mono-crystalline solar panels.

The key differences between poly- and mono-crystalline panels are in efficiency and cost. Typically, mono-crystalline panels are more efficient (and thus more expensive) than poly-crystalline panels.

Inverters

The cells in your solar panels collect the sun’s energy and turn it into direct current (DC) electricity. Most homes and businesses, however, use alternating current (AC). Inverters change the DC electricity from your panels into usable AC electricity. There are three basic approaches to solar inverters.

String (or centralized) inverter: A single inverter is used to connect your entire array of solar panels to your electrical panel. String inverters are the least expensive inverter option, and cost less than micro-inverters. However, if one of the panels stops producing electricity, even due to temporary shading, it can bring down the performance of the whole system.

Micro-inverters: If you choose micro-inverters, one will be installed at each solar panel, which allows each panel to maximize production. If some of your panels are shaded at different times of day or if they aren’t all installed facing the same direction, micro-inverters will minimize performance issues. The cost of micro-inverters tends to be higher than the cost of string inverters.

Power optimizers: Systems that use power optimizers are a hybrid of micro-inverter and string inverter systems. Like micro-inverters, power optimizers are installed at each panel. However, instead of converting the DC electricity from the solar panels into AC electricity, the optimizers “condition” the DC electricity before sending it to a centralized inverter. Like micro-inverters, they perform well when one or more panels are shaded or if panels are installed facing different directions. Power optimizer systems tend to cost more than string inverter systems, but less than micro-inverter systems.

Racking and Mounting Systems

Racking and mounting systems are used to affix your solar panels either to your roof or to the ground. They also allow you to position your panels at an angle that is best for capturing the sun’s rays.

To perform at their best, solar panels should face south and be installed at an angle between 30 and 45 degrees (depending on how far you are from the equator). Panels facing east or west and at a pitch angle of five degrees or more will still work well, but will produce 10 to 20 percent less electricity than those installed under ideal conditions.

There are two types of mounts: fixed mounts, in which the panels remain stationary, and track mounts, which allow panels to “follow” the sun as it moves across the sky during the day (single-axis track mounts) and during the changing seasons (dual-axis track mounts). Track mounts are only suitable for panels installed on the ground.

Batteries

To appreciate why you might choose to install a solar-plus-storage system for your home, you first need to understand how a standard home solar PV system functions.

The typical solar energy system includes solar panels, an inverter, equipment to mount the panels on your roof, and a performance monitoring system that tracks electricity production. The solar panels collect energy from the sun and turn it into electricity, which is passed through the inverter and converted into a form that you can use to power your home.

The vast majority of residential solar energy systems are connected to the electricity grid (or “grid-tied”). When your panels are producing more electricity than your home needs, the excess is fed back into the power grid. Conversely, when your home needs more electricity than your solar panels are producing, you can draw power from the electric grid.

In most cases, you receive a credit on your utility bill for the electricity you send back to the grid. Later, when you are using more electricity than your solar panels have generated, you can use those credits instead of having to pay more to your utility. This process is known as net metering (The Nigerian national grid is unfortunately not able to provide this functionality at the moment).

Solar batteries work by converting the DC energy being produced by your solar panels and storing it as AC power for later use. In some cases, solar batteries have their own inverter and offer integrated energy conversion. The higher your battery’s capacity, the more solar energy it can store.

When you install a solar battery as part of your solar panel system, you are able to store excess solar electricity at your home instead of sending it back to the grid. If your solar panels are producing more electricity than you need, the excess energy goes towards charging the battery. Later, when your solar panels aren’t producing electricity, you can draw down the energy you stored earlier in your battery for night use. You’ll only send electricity back to the grid when your battery is fully charged, and you’ll only draw electricity from the grid when your battery is depleted.

What this means in practical terms is that homes with solar-plus-storage can store excess solar power onsite for use later when the sun isn’t shining. As a bonus, since solar batteries store energy at your home, they also offer short-term backup power in the event that there’s a power outage in your area, a frequent occurrence in Nigeria :-).

Solar Batteries are not optional in Nigeria as we all experience consistent power outages.

Performance and Monitoring

Performance monitoring systems provide you with detailed information about the performance of your solar panel system. With a monitoring system, you can measure and track the amount of electricity your system produces on an hourly basis.

While some solar installers charge extra for installing a monitoring system, it can provide significant value over the lifetime of your solar panels. Monitoring systems help you identify any performance issues to ensure that you maximize the electricity production (and therefore the financial returns) of your solar panel system.

There are two types of monitoring systems:

  • On-site monitoring: The monitoring device is physically located on your property and records the amount of electricity produced.
  • Remote monitoring: Your solar PV system transmits its performance data to a monitoring service that you can access online or with a mobile device.