Terms appeared in the design of off-grid PV systems (Peak Sun Hours, Safety factor, Autonomy days)

The factor of safety (Safety Factor)

It is  employed  to  make  sure  that  the  PV system can handle a load current more than that planned due to addition of equipment. This is also to take into account any decrease in production due to any external conditions.

This safety factor allows the system to slightly expand.

Sf = 1.15 for domestic applications whereas it may be 1.4 for critical load such as communication equipment.

The peak sun hour (PSH)

The average daily solar insolation in units of kWh/m2 per day is sometimes referred to as "peak sun hours“.

It refers to the solar insolation which a particular location would receive if the sun were shining at its maximum value for a certain number of hours.

OR, it is number of hours must the sun shine at a solar intensity of 1000 W/m2 to produce the annual daily solar insulation. It is a site specific.