Medium Off-Grid AC System

What it is

These Off-Grid systems offer an alternative to bringing in mains electricity to a remote location or or mobile application where AC power is required.

How it works

Solar AC Off-Grid Systems

Here all the loads are run on AC using an inverter to convert power stored in the battery bank to 230 VAC. This simplifies wiring since low cost readily available cable, switches, outlets and fittings can be used, together with standard appliances.

Normally, the battery bank voltage will be 24 or 48 VDC instead of 12 VDC to reduce cable sizes.

The charge in the battery bank is then maintained using a PV array connected to the battery via a solar charge controller.

Good solar resources are important in order for the energy demand to be satisfied even when weather conditions are poor.

  • The solar PV array must be sized so it is able to put sufficient power into the batteries to maintain demand at all times of the year.
  • The inverter must be sized to meet the maximum electrical load that is needed i.e. to run all appliances that might be on at the same time.
  • Often fuels other than electricity are used for heating and cooking.

Wind-Solar Hybrid AC Off-Grid Systems

Adding a wind turbine can provide more consistent year-round generation.

Solar - Diesel Hybrid AC Off-Grid Systems

Including a diesel or LPG generator as back-up for times of poor weather or to power peak loads can be an economical alternative since the other system components do not need to be sized to suit worst case conditions.

In these systems the inverter also works as a charger (inverter charger) this means AC power from the diesel generator can be converted back to DC to charge the batteries.

  • Generator charges battery and runs loads when batteries become low.
  • Generator can also run peak loads - giving savings in inverter cost and allowing a smaller battery bank to be utilised.
  • Generator can be automatically started and stopped using the inverter/charger.

Adding a petrol, LPG or diesel generator can be economical since you don't have to size the rest of the system for worst case weather conditions.

Often for places without any mains electricity a generator will be the existing source of power so adding a battery store with inverter/charger and additional wind and/or solar generation is the perfect way to reduce fuel costs and to make 24/7 power available without running the generator continually.

What it can power

This sort of system could comfortably power everything you would expect in a standard house, office or small industrial unit.

Different sizes of inverter charges can be chosen to meet your requirements, several can be used in parallel for bigger applications or multiples of three can be used for three phase.

What's in the system

As an example here is a list of components in a typical medium off grid solar PV system:

  • Solar PV panels
  • Solar Charge Controller
  • Diesel generator
  • Inverter or Inverter/Charger
  • Batteries
  • Battery cables
  • Battery fuse
  • Distribution board
  • AC circuitry
  • DC solar cable & connectors
  • Normal AC cable

What next

AC Off-Grid systems require the involvement of a professional electrician to ensure a safe and compliant installation.

We work with a large network of installers, many of whom we have known for a long time and who have received training at Wind & Sun so we can usually recommend an good local installer to you who can help.