Clean energy continues to gain momentum — as these technologies improve and develop, the energy economy is making a historical transition. I’ve noticed more blue and black screen panels popping up on house and business rooftops, and my first thought is always, “Good for them!” Then I find myself in a moment of wonder — how do those magic energy boxes actually work?
Surprisingly, the idea of solar energy has been around since 1839, when Alexandre Edmond Becquerel discovered that certain materials create electric sparks when struck by light from the sun. Harnessing this energy into PV cells (photovoltaic cells), or solar cells, was discovered later in the 1800s and further described by Einstein in the bloom of twentieth-century physics.
A solar panel is a set of solar cells, and each solar cell is like a sandwich. The bread of the sandwich is the two semi-conductive layers of material, typically crystallized silicone. On its own, crystallized silicone isn’t a great conductor, so it goes through a process called “doping” wherein the silicone crystals are doped with impurities to increase their conductivity. The bottom layer is doped with Boron to bond with a positive charge (P), while the top is doped with Phosphorus and facilitates a negative charge (N). When sunlight enters the cell, the doped silicon layers knock electrons loose.
The best part of the sandwich (the jelly between the bread) is called the P-N junction.
This is where the mystery and magic happens. The electrons want to flow from the negative layer to the positive layer, but the electrical field in the P-N junction prevents this from happening. The P-N junction forces the electrons to jump from the positive layer to the negative layer within a circuit, creating a flow of electrical current — much like the positive and negative sides of a battery. This flow of electrons is what we know as electricity, powering our lights, computers, phones and vaporizers.
One solar sandwich cell only generates a few watts, so they are linked together into a module or panel; these units can also be grouped together into a larger system called and array — or maybe it should be called a buffet? — of solar sandwiches. These groups are wired to an external circuit, which harvests a supply of electricity for immediate use or excess reserves to flow and integrate back into the grid.
A large benefit of solar power is that it is harvested when and directly where power is needed, helping to meet peak demands of energy on the grid. A great example are those muggy, lethargic days where everyone has their AC on arctic full blast. Those are perfect days for solar panels to kick in and supplement the grid. This on-site generation also reduces the chance of a loss of electricity through the transmission of electrical currents from a distant power source. Have you ever stood near or beneath a transmission tower and heard that fuzzy snapping sound? That eerie crackle is an audible expression of lost electricity. You may have also noticed that on hot days, power lines may sag more than usual. This is not only a result of gravity, but heat causing expansion in the lines and making them droop.
Unlike traditional power plants, which result in large failures if only a part of the system is damaged, a large solar system will continue to harness and produce electricity even if a section is damaged. The largest benefit of solar energy, however, is that it is 100% clean and renewable.
A challenge of current solar power technology is having energy flowing from customers rather than tothem. This is a sticky situation for utility companies. If a community can create more energy than they use, the “feeder” lines running from the community to the utility may not be capable to handle the flow of electricity in the opposing direction. This challenges grid operators, as they can no longer control the fluctuations and output of the system, creating instability on the grid. Solar is also dependent on the weather; condition changes can drastically influence the amount of energy being produced. Additionally, large-scale solar arrays situated far from urban centers also face a loss of energy through transmission, just as non-renewable energy sources do.
These challenges are only a piece of the puzzle of our future energy economy. As we have already seen, as technology rapidly develops, it adapts to human needs; we need only to continue seeking solutions for storage and grid stability.