In this post I would like to go over the basics of a solar system such as what components are needed and what function they perform in the system. There are four primary items in an off grid solar system. They are the Solar panels, Charge controller, Battery bank, and Inverter. There are many other components needed to set up a solar system such as cabling, connectors, fuses, disconnects, etc. I will go into more detail when I go over an example system.
Solar Panel – Solar panels or groups of panels (an array), are what collect the energy from the sun. The output is DC voltage and output is dependent on the manufacturer. Each solar panel will have a rating tag located usually on the back of the panel. They have information you will need to properly size the rest of your system. These tags will have the wattage rating, voltage open circuit, current short circuit, and usually also state the voltage and current maximum power point.
Charge Controller – The charge controller is used to take a higher voltage dc power from the solar panel and charge a battery bank. If we look at one of Victrons controllers, the SmartSolar 100/50 it will accept a maximum 100 volt dc from the solar panels and can charge a 12 or 24 volt battery bank at upto 50 amps of current.
Battery Bank – Batteries come in all shapes, sizes, and chemistries however their purpose is to store the power from the solar panel for use at a later time. The most common types are lead acid, sealed AGM, and lithium. Lead acid batteries are the cheapest option with regards to up front cost however lithium is an excellent option due to their lifespan.
Inverter – The Inverter is what will generate AC power needed to run most devices/appliances around your house. The inverter will take the DC power from the battery bank and create AC power. The Inverter will need to have the same voltage rating for the battery bank you are using. Each inverter will have a wattage rating as well as a surge rating. For instance if we look at a common Aims Inverter it might have a rating such as 24VDC 1500/3000 watts which means it will accept a DC voltage range centered at 24 Volts and has a continuous wattage rating of 1500 watts with a surge load of 3000 watts. The surge load is when you first turn on something that has an electric motor or inductive loads. If we look at a vacuum cleaner it may only draw 10 amps at 120 volts AC once it is up to speed however when it is first switched on it may draw 2 to 3 times the current which is our surge.