How does the electricity transmit？
There are two main ways electrons move - DC(Direct Current) and AC(Alternating Current).
Let’s take a look at this battery. There's a positive(red) and negative(black) terminal, you connect it to an appliance while attaching two wires to both terminals of the battery.
While it’s connected, the electricity will flow in one direction and it goes out one side of the battery to the appliance and flows out of the appliance back to the battery.
This is a typical DC(Direct Current) system, think of it like a lazy river, the electricity flows in one direction from the battery to whatever needs power. Your car's battery uses DC to keep things humming.
The AC(Alternating current) system is more like ocean waves crashing on the beach. Instead of a steady flow, the positive and the negative are switching at a very high frequency(e.g. 60Hz in North America), the electricity is actually vibrating in an AC system.
But don’t worry, it’s not a physical vibration so the wires won’t vibrate. Technically it’s called oscillation. The oscillation transmits power across distances, that's how the grid brings electricity to your home. It means in an AC system, there is no positive and negative, the electricity is being transmitted through vibrations(or oscillation), so there’s no flow at all.
If the DC system is like a river and flows in, in an AC system, the direction electricity flows reverses rapidly, like a wave going across an ocean, the wave transmits over distance in an ocean, the force moves but the ocean does not.
In a DC system, the electricity flows continuously through the wire in one direction.
In an AC system, the direction electricity flows reverses rapidly that it vibrates to transmit the electricity.
Understanding electrical measurements
Now we know how electricity transmits, let's talk about how to measure the electricity. By the nitty gritty - Volts, Amps & Watts.
Voltage is the force of the electricity, it measures the electrical pressure. The electricity is very similar to a garden hose with water and the voltage is the pressure of the water.
Whether the water is flowing through the hose or not, the pressure is constant like the voltage is always there. Because the voltage is the energy potential or how much force is ready to be used, it can tell you what appliances you can hook up to your electrical system.
If you have a 12-volt appliance, you can hook up to a 12-volt battery, same as a 110-volt appliance hook up to a 110-volt battery, you can think of voltage as a way to understand compatibility.
Amperage is the rate of electrical flow, the amp rating will determine how big the wire needs to be when attaching electrical components.
In the garden hose example it will be the thickness of the water hose, the thicker it is the more water can go through.
If you have a 24-volt appliance, you can hook up to a 24-volt battery, and you will need a wire that is large enough to carry the number of amps required for that load.
Watts is a combination of volts and amps, it‘s simply the voltage times amperage and that will tell you the total amount of electricity going through a system, and shows you how much power overall it's generating or consuming.
Let's do some simple calculation, now we have a solar panel that produces 10 volts but only 1 amp, that means that volts times the amps you will have 10 volts x 1 amp = 10 watts.
If the sticker on the back of an appliance shows the wattage and the voltage but doesn't tell you the ampere, now you know how to figure it out.
On your electricity bill, it will tell you how many kilowatt hours or thousands of watts of hours you have used, that's the wattage times the hours, what are called Watt-hours.
- If you use 100 watts for one hour, that's 100 watt-hours;
- If you use 1,000 watts for one hour, that's 1,000 watt-hours or one-kilowatt hour/1kWh.
It's very simple in the watt-hour to understand how much electricity an appliance is generating or consuming over time, or use watt-hour to determine how much electricity a battery can store.
It’s the best way to compare batteries, you can determine how long it can power your appliances, and how long it will take to recharge with a solar power system or an AC charger by the watt-hour rating of the battery.
- If you have a thousand-watt-hour storage battery and want it to power a 50-watt load, we can take thousand-watt hours and divide it by 50 watts, then we know how many hours it can power for, which is 20 hours.
- Let's do a second example, we have a 100-watt hour battery and we want to power a 20-watt load, we can do it for 5 hours.
Use volts and amps to figure out the wattage, then use watts with time to figure out watt-hours.
Watt-hours is the best metric to determine how big a battery is, how long it takes to recharge, how long you can use that battery to power your loads and everything else.
Before we move forward, let's take a look at these batteries for a sec.
Like this 12-volt battery, it has 200 amp-hours, that means that it can produce 200 amps for 1 hour at 12 volts.
Here's another battery that shows 6 volts and 225 amp-hours. Again, that means that it can produce 225 amps for 1 hour at 6 volts.
The amp-hour rating only applies to that stated voltage, but you have some flexibility to change the voltage and current levels. By using different wiring configurations between components.
This brings us to parallel and series connection systems. By joining up batteries, solar panels or other electronics in specific ways, you can manipulate how the voltage and amps are distributed.
What is Parallel & Series Connection?
Parallel Connection means connecting all the positives to one wire and all the negatives to another wire, like widening a river - more can flow at once without changing pressure.
In a parallel connection, the voltage or the pressure of electricity will not change, but the amps will beef up.
- If you parallel connect all of these 3 solar panels and each one produces 6 amps, you will get 18 amps.
- It shows in parallel connection, the amps will go up and the voltage stays the same as 18V.
Series Connection means you connect the positive of one to the negative of the one next to it, like making a string or a daisy chain of these panels end to end - the river gets longer with the same flow.
In a series connection, the voltage will rise but the amps will stay the same.
- Let's say we still have those same 3 solar panels and they all produce 6 amps. Instead of producing 18 amps with a parallel connection, they will still only produce 6 amps with a series connection, but the voltage will go up.
- All together when series connected, they will produce 18 volts instead.
So you can change the voltage and the amp rating of certain components including batteries and solar panels by connecting them in various ways.
In summary, parallel connection combines components for increased current, while series connection increases voltage.