We have created this simple overview of solar energy because learning about solar can feel overwhleming. However, we promise you’re capable of learning the basics, and then before you know it, solar terminology and technology will be part of your everyday vocabulary.
Let’s begin!
Solar Energy Overview
At a basic level, electricity is electrons moving through a circuit. However, the process by which sunshine generates electricity inside a solar system is worth taking a moment to understand.
Sunlight activates the panels, which are constructed of silicon cells, a metal frame, a glass casing enclosed in a film, and wiring. It is best to group panels into an array (a fancy way of saying an ordered series) and place them on rooftops or large ground-level spaces. The solar cells (also called photovoltaic cells) absorb sunlight during the day.
Next, the solar cells produce an electrical current via a thin semiconductor wafer constructed from two layers of silicon. An electric field is created because one layer is positively charged and the other is negatively charged. Light energy from the sun hits a photovoltaic cell, energizes it, and causes electrons to “come loose” from atoms in the wafer. These loose electrons in motion create an electrical current.
Now, the electrical energy is converted into direct current electricity (also called DC electricity), which cannot power most homes. We need that DC electricity to become alternating current electricity (also called AC electricity). Thankfully, there is a piece of equipment that can change DC electricity into AC electricity: an inverter!
Solar panels have absorbed sunlight and created an electrical current, and then that current was converted from DC electricity (can’t power a home) to AC electricity (can power a home) by an inverter. Next, this newly converted electricity powers a home by supplying electricity just like the traditional electrical utility grid does.
Differentiating kW and kWh
This distinction is important for a variety of reasons, and an understanding of the difference is important for both quoting customers and sourcing materials. Power and energy are two different things when talking about solar energy and solar installations.
Power (kW) can be thought of as how fast electricity is consumed or generated. From a customer standpoint, this is how we talk about the size of a solar energy system: its peak output in kW. It is worth noting that power’s fundamental unit is joules/second, though you’ll likely only hear electricians and engineers throwing around that unit of measurement. Energy (kWh) is measured in kilowatt-hours, and describes how much electricity is consumed, generated, or stored over time.
Introduction to Solar Batteries
Installing a solar energy system can lower energy bills or eliminate them outright with an off-grid system. The question most people have about solar can be generalized as, “How do I get energy at night?”
The answer: solar batteries.
Solar batteries store excess generated energy to call upon when needed, and also provide backup energy in the event of a blackout.
Home Solar System Components Overview
There are three critical components for a home system: panels, inverters, and racking/mounting. Solar panels use different cell types and arrangements, including:
- Polycrystalline
- Monocrystalline
- Half-Cut
- Shingled
Panels generally also come in residential and commercial sizes; despite that, either can be used on a residential roof. Commercial panels are often bigger and can generate more wattage; however, they are larger and heavier than the residential versions.
Inverters can be the size of luggage (string inverters) or the size of a book (microinverters). Microinverters are generally the more expensive of the two and are attached to the back of or underneath (or placed beside) each solar panel. String inverters attach to a wall and the panels connect directly to it.
However, there is an attractive third option: power optimizers.
Racking/mounting is critical because the solar panels need a home. If there is space on the roof, then racking is the right option. If a customer doesn’t have the space, then a ground-mounted unit is necessary.
Panel Angle & Direction
A critical component for optimizing a solar installation is understanding the best direction/angle for the panels. Let’s begin with a simple fact: the sun rises in the east, and then sets in the west.
With us so far?
This simple fact helps us understand the first step of roof direction/angel basics:
- East-facing panels generate the greatest amount of power in the morning.
- West-facing panels generate the greatest amount of power in the late afternoon.
- South-facing panels have the greatest overall power generation, but will still generate less in the morning and late afternoon than east- and west-facing panels, respectively.
Panel angle can vary greatly in terms of maximizing energy production. However, the easiest way to understand angle is that the ideal angle is most likely the angle the roof was built at (unless, of course, the roof is flat). If you are dealing with a flat roof, then you will have to use tilt frames in order to create an angle.
Thanks for reading!