The humble resistor is a key component of many renewable energy systems. They are designed to resist electricity and can therefore be used to supply the correct voltage or a suitably limited current to the various components in an electric circuit.

Because resistors are so small – too small to print numerical resistance values on – they are instead marked with four, five, or (less commonly) six coloured bands. Each colour represents a different number and so the value (in Ohms) of the resistor can easily be calculated.

Resistor Colour Code Chart

The last coloured band is usually used to indicate the tolerance – a measure of how accurate the stated resistance is, i.e. 1%, 2%, 5%, or 10%. In the case of six band resistors, is used to show the temperature coefficient – a measure of how much the resistance of a resistor is changed by changes in temperature.

Remembering the Resistor Colour Code Values

There are many mnemonic phrases to help you to remember the order of the colours:
Black Brown Red Orange Yellow Green Blue Violet Gray White
…which correspond to the values 0-9. For example:
Bad Beer Rots Our Young Guts But Vodka Goes Well.