How about some gratitude for our sun? It does a great many things for the earth, but one of our favorites here at Independent Power Systems is the free daily delivery of an incredible amount of clean energy. How much energy does our planet receive, you ask? Theoretically, more energy from the sun strikes the earth in one hour than the world uses in an entire year. Some 430 quintillion Joules (430 with 18 zeroes after it) of energy is sent to earth every hour!
If you’re a home or business owner equipped with solar panels, you’re in a great position where you can benefit even more from this near-endless supply of free energy by converting the sunshine into electricity at the end of its 93 million mile journey. By powering your home with solar photovoltaics (PV), you’re reducing your demand from the grid and saving money on your utility bills in the process. Any energy you aren’t consuming can either be stored in a battery storage device for use later or exported back to the grid for energy credits.
But how are solar panels able to convert this energy in the first place? To explain this process a little more, we’ll first explore in detail some of the components that make up a solar panel and how they work together to create clean, renewable energy for your home.
COMPONENTS OF A SOLAR PANEL
A solar panel is generally made up of a grid of photovoltaic cells (to be explained shortly), a metal frame, and a glass casing that protects the cells from the elements. There is also a layer of insulation under the glass casing and protective backing behind the cells that help manage heat and humidity. Most commonly, there are 60 or 72 photovoltaic cells that make up one solar panel.
Each photovoltaic cell is made up of a semiconducting material, usually silicon. The silicon is manufactured with trace amounts of other materials to establish certain electrical properties. The addition of phosphorus gives silicon atoms an extra electron, creating a negative charge. A boron treatment makes silicon atoms lose one electron, which creates a positive charge.
A photovoltaic cell has one layer of negatively charged silicon on top of a positively charged silicon layer. Also inside each cell are metal wires or a metal backing plate, which will capture and direct the electrical current once it is created.
RAYS TO WATTS: HOW SUNSHINE BECOMES ELECTRICITY
A ray of sunshine is made up of energy particles called photons. Photons transfer this energy whenever they collide with other particles. That energy usually transfers to other particles in the form of heat (a fact that every cat currently in a windowsill is thankful for).
However, these photon collisions can create electricity when they excite the electrons in any atoms they collide with, so much so that these electrons break away. When photons land on a solar panel they knock electrons free from the silicon and the electric field created by the positive and negative layers pull it into motion. This electron motion, aka electrical current, is then captured by conductive metal in the solar cell that transports that energy to a solar inverter. In some cases, solar panels will use Module-Level Power Electronics or MLPEs, usually power optimizers or micro-inverters attached to the backs of the panels, which will optimize the energy from panels directly before sending it to a central inverter.
Solar panels generate direct current (DC) electricity, but homes and appliances use alternating current (AC). The solar inverter converts the incoming DC from the solar panels (or from the MLPEs on the backs of the panels) to AC then sends it on to a breaker box. From there, electricity is distributed throughout the home as needed.
If the solar panels produce more electricity than is being used in the home, and the system is tied to the grid, the surplus energy is sent back to the grid to be used elsewhere. This is a process called net-metering, and most utilities will credit homeowners for any solar power exported to the grid. At the end of the month, these credits can be used to offset any electricity draw from the grid, with unused credits typically rolling over into the following month.
FACTORS THAT INFLUENCE SOLAR PRODUCTION
Shade means that fewer photons get through to land on photovoltaic cells and excite electrons. Minimizing shade from trees and adjacent buildings maximizes electricity production. If your roof has a lot of obstructions like vents or chimneys, these may also cause some shading issues and limit the system size you’re able to install.
Solar panel production changes over the course of the year as the number of sunshine waxes and wanes with the weather. More clouds mean more shade and less production. Snow limits production too. Solar panel’s efficiency will also dip with extreme heat or cold.
The angle of a solar panel also boosts production. For southward facing panels the ideal tilt is usually between 30 and 45 degrees.
The azimuth angle is the direct sunlight is coming from. At noon in the Northern Hemisphere, the sun is coming from the south, which is an azimuth of zero. Generally, south-facing panels will produce the most. However, if constraints require panels to face other directions they can still be productive.
GETTING STARTED WITH SOLAR ENERGY
Don’t yet have solar panels for your home yet? Get started with a free consultation with one of our solar experts to see how much money you could save. Thanks to that great big ball of fire in the sky, there’s plenty of solar energy to be had for all!