How does a solar powered system work? We could go all technical, but I fell asleep writing it and I know you would fall asleep reading it, So, let’s keep it nice and simple!
Solar Panels
Plants use a process called photosynthesis to make energy. Plants trap light energy and the chlorophyll uses that energy to create the energy to enable growth.
Solar panels work in a similar way. They contain semiconductor materials, which is normally silicon. When exposed to sunlight, they produce energy in the form of an electrical charge, called Direct Current (DC) Several panels are connected into what is called a series string or strings, depending on the size of the system.
Inverter
So, what’s the difference between DC and AC and why does the inverter need to make the conversion? DC flows in one direction, from positive to negative. It is a constant and graphically looks like this:
AC alternates or cycles from positive to zero, down to negative, back to zero and back again to positive a given number of times per second and this is what it looks like on a graph:
In Europe, the standard coming in from your electricity provider is Alternating Current at 230 Volts, 50 Hertz, so how does the inverter convert the DC from the panels into AC for the house?
You know what DC looks like, lets add some electronics into the equation. If we take the DC and switch it with reference to zero, it shows a negative voltage like this:
Now by using high powered fast electronic switches and switch the DC, we can produce this:
We’re not there yet; try to run any household appliances (TV, fridges, computers etc) from this and you will almost certainly wreck them. Run it directly into the mains and you’ll blow every fuse in the house and likely annoy your electricity provider!
The inverter must “smooth” this output, turn it into a pure sine wave keeping it at 230 Volts AC / 50 Hertz and ensure it is synchronised (in phase) with the mains coming in from the street so that there are no voltage or current differences between the inverter output and the mains supply input, so you end up with this:
There’s more.
Besides regulating and synchronising itself with the mains, the inverter also monitors for:
- Variations in the street supply with voltage and / or frequency. This is where the inverter will shut down to protect itself.
- Loss of power from the street supply. The inverter will shut down to avoid feeding back into the grid to protect the repair engineers.
- Low light levels such as nighttime or snow covering the panels. In the case of low light levels, the inverter will go to standby, only waking when there is enough power to supply itself AND supply power into the house.