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Solar Panels: What is solar energy and how do panels work?

Solar energy works by capturing energy from the sun “by a solar panel” and turning it into electricity for your home or business.

Our sun is a natural nuclear reactor. It releases tiny bundles of energy called photons, which travel 93 million kilometers from the sun to Earth in about 8.5 minutes. Every hour, enough photons affect our planet to generate enough solar energy to theoretically meet global energy needs for an entire year.

Currently, photovoltaics represent only five-tenths of one percent of the energy consumed. But solar technology is improving and the cost of solar energy is falling rapidly, so our ability to harness the sun’s abundance of energy is increasing.

A 2017 report by the International Energy Agency shows that solar energy has become the fastest-growing energy source in the world – marking the first time that the growth of solar energy has surpassed that of all other fuels. In the coming years, we will all be enjoying the benefits of solar-generated electricity in one form or another.


Solar Panels: What is solar energy and how do panels work? - solar panel

When photons hit a solar cell, they release electrons from their atoms. If conductors are connected to the positive and negative sides of a cell, it forms an electrical circuit. When electrons flow through this circuit, they generate electricity. Multiple cells form a solar panel and multiple panels (modules) can be connected to form a solar panel. The more panels you can deploy, the more energy you can generate.


Photovoltaic (PV) solar panels are made up of many solar cells. Solar cells are made of silicon, like semiconductors. They are built with a positive layer and a negative layer, which together create an electric field, just like in a battery.


Photovoltaic solar panels generate direct current (DC) electricity. With DC electricity, electrons flow in one direction around a circuit. This example shows a battery powering a lamp. Electrons move from the negative side of the battery, through the lamp, and back to the positive side of the battery.

With alternating current (alternating current), electrons are pushed and pulled, periodically reversing direction, much like the cylinder in a car engine. Generators create AC electricity when a coil of wire is rotated next to a magnet. Many different energy sources can crank this generator, such as gas or diesel, hydroelectricity, nuclear, coal, wind, or solar.

AC electricity was chosen for the US power grid mainly because it is less expensive to transmit over long distances. However, solar panels create direct current electricity. How can we get DC electricity from the AC grid? We use an inverter.


Solar Panels: What is solar energy and how do panels work? - solar panel

A solar inverter takes DC electricity from the solar panel and uses this to create AC electricity. Inverters are like the brains of the system. Along with reversing direct current to alternating current, they also provide ground-fault protection and system statistics, including voltage and current in AC and DC circuits, power production, and maximum power point tracking.

Central inverters dominated the solar industry from the start. The introduction of micro-inverters is one of the biggest technological changes in the PV industry. Micro-inverters optimize for each individual solar panel, not an entire solar system like central inverters do. This allows each solar panel to work at its full potential. When a central inverter is used, having a problem with one solar panel (perhaps it is in the shade or it is dirty) can reduce the performance of the entire solar panel, make this not a problem. If one solar panel has a problem, the rest of the panels will still perform efficiently.


Solar Panels: What is solar energy and how do panels work? - solar panel

Here is an example of how a home solar power installation works. First, sunlight hits a panel on the roof. Panels convert the energy into a direct current, which flows to an inverter. The inverter converts the electricity from DC to AC, which you can use to power your home. It’s beautifully simple and clean, and it’s getting more efficient and affordable all the time.

However, what happens if you’re not home to use the electricity your solar panels are generating every sunny day? And what happens at night when your solar system isn’t generating real-time power? Don’t worry, you still benefit from a system called net metering.

A typical grid-tied photovoltaic system, during peak hours of the day, often produces more energy than a customer needs, so the excess energy is fed back into the grid for use elsewhere. The customer gets credit for the excess energy produced and can use this credit to extract from the conventional grid at night or on cloudy days. A grid meter records the energy sent against the energy received from the grid.

Another article on this blog that may interests you:

Solar Panel: What do you have to keep in mind if you want to install this at home?