My wife, who also happens to be my editor – I don’t exactly have a payroll for this blog – was reviewing an article I wrote the other day, and had no choice but to admit she didn’t have a clue what I was talking about. It’s kind of hard to edit something when everything reads like gibberish. “What’s MPPT?” “What’s a watt hour?” “What’s an inverter?” “What’s a PV panel?”
After some debate over my writing style, we concluded I shouldn’t assume my average reader is a building scientist. She suggested writing a companion article. One that breaks down all the jargon. So that’s what this is. Whether you’re shopping for solar panels, a generator, or parts; if you don’t know what any of the numbers or nomenclature means, this guide is for you.
Photovoltaics is the process of light being converted into power. Building scientists and other industry professionals have a tendency to call solar panels, “photovoltaic panels,” “PV panels,” or simply “PV.”
Amperage and Ampere
Amperage is the strength of an electric current expressed in amperes, or “amps.” The higher the amperage, or the greater the number of amps, the stronger the current.
Voltage, in simplest terms, is the pressure, or potential, of an electric current measured in volts. A small number of volts can be thought of as a creek, whereas a large number of volts can be thought of as a river. The strength of the current, however, is still determined by the amps. What’s most important to understand is that the flow of creek can be just as fast, or strong, as the flow of a river; but the rapid river is much more powerful because the volume is so much greater.
Wattage is the total amount of power being consumed by a device measured in watts. If you multiple the amps of a device by the voltage, you get the number of watts. For example, a device that uses 5 amps and 20 volts, operates at 100 watts.
A watt-hour, or wh, is the number of watts consumed by a device operating for one hour. If we use our example above, our hypothetical 100W device will consume 100wh for ever hour of continuous use. Watt-hours can also be a measurement of a batterie’s capacity. A 1000wh battery can power a 1000W device for one hour, or it can power a 100W device for 10 hours. A kilowatt- hour, or kwh, is 1000wh.
An amp-hour, or ah, is the same as a watt-hour except measured in amps. Some people prefer to think in amps instead of watts, even though they are different metrics. Personally, I prefer to think in watts since it is easier to calculate total power consumption over an given duration of time.
An inverter is the part of a generator that converts the direct current (DC) from the solar panels to a usable alternating current (AC), like the wall sockets in your house. The inverter is also what houses all of the generators ports: 120V AC, 12V DC, USB, etc.
A charge controller regulates the current going in and out of the generator. Its main function is to restrict too much power going in to or out of the generator at any given time. Charge controllers also have a direct impact on how fast or slowly your generator charges from any given power source.
PWM stands for Pulse Width Modulation. PWM is an older, cheaper, more common, and less efficient charge controller technology. Most solar generators still come with PWM as the default charge controller, though this is likely going to change in the near future.
MPPT stands for Maximum Power Point Tracking. It is a newer type of charge controller technology that is more efficient than PWM – i.e, it can charge your batteries faster. MPPT is usually an upgrade on most solar generators.
APP stands for Anderson Powerpole, invented by Anderson Power Products. It is a type of cable that is widely used for sending power from solar panels to the generator. It is also commonly used within the generator itself.
MC4 is a type of connector that is typically used for connecting solar panels. Most panels these days already come with a positive and negative wire on the back fitted with MC4 connectors.
Lead Acid Battery
Lead-acid batteries were the first type to be used for most solar power banks. They are exactly the same kind of battery used in cars and boats. Lead-acid batteries are cheaper than other options, but less efficient than newer technologies. Even the cost savings is questionable when you factor in how much less efficient they are. Nevertheless, they are still commonly used today. Fun fact: The lead-acid battery was invented in 1859 by German physicist, Gaston Planté.
Lithium ion batteries have become the new standard for solar generators, power banks, and power packs. They are more expensive than lead-acid but more efficient. The main difference being you can fully charge and drain lithium ion batteries over and over again without damaging the batteries. Lead-acid, on the other hand, should never be drained below 50% capacity.
LiFePo4 stands for Lithium Iron Phosphate, or LFP. It is another type of lithium ion battery that is safer and longer lasting than stand lithium ion batteries. It is currently the most expensive option.
Monocrystalline is a solar panel made from a single series of photovoltaic cells. It other words, it is one solid piece, like a solid piece of glass. It is the most efficient type of solar panel.
Polycrystalline is a solar panel made out of fragments of PV cells. Think of it as a shattered piece of glass that has been glued back together. The are less expensive but less efficient than monocrystalline. If you want to know all of the differences between these types of panels, read my comparison article here.