Going off-grid

To determine your payback period on a solar PV/battery system, here are some things you should consider:

• The purchase price
• Solar panel capacity required
• Usable battery capacity required
• System maintenance costs
• The loss of an existing feed-in tariff
• The future price of electricity (will it go up or down, and by how much?)
• Your electricity usage – both your daily peak demand and your total use in an average week.

You should also consider if you’ll stay in your home long enough to recover your costs.

Discuss your ideas with a number of solar PV/battery suppliers to see what options they suggest.

Considering your daily electricity use, is there enough of your roof in the sun for the number of panels you’ll need? If you don’t have enough roof space, you may need to mount panels on your shed or even on the ground. This could come with further set-up costs.

Having an off-grid electricity system means thinking about the right size generation and storage to get you through your peak daily needs and a run of cloudy days. Your solar PV/battery system won’t supply power if:

• The battery has been fully used at night-time and needs charging
• There is a system fault or breakage
• It is undergoing scheduled maintenance.

If you can’t do without power at those times, you’ll need a back-up generator to meet your basic electricity needs. A generator must be housed somewhere safe with appropriate ventilation and not cause a disturbance (e.g. noise and smell). Generators will run best when maintained regularly and refuelled. Read more about generator safety and use.

Your electricity use varies greatly within a day, with regular high spikes of demand for very short times. Air conditioners and pool pumps can create short bursts of high demand when starting, often only lasting a few seconds.

An off-grid system's inverter must be able to supply this high start-up power or the appliance may not start properly. This demand is additional to other electricity loads running at the same time, for example the TV, fridge, computer, etc.

If your inverter cannot supply these high spikes in demand, you may have to give up some non-essential appliances, or use them less and more carefully. Otherwise, you may have to install a larger solar PV/battery system at a higher cost.

Going off-grid usually requires some lifestyle changes, depending on the type of appliances you have and your electricity demand.

Energy-saving habits and energy efficient appliances will help to prevent your system cutting out or not having enough power to run your home. Also, you can consider the impacts of:

• Having house guests
• A particularly cold winter or hot summer
• Hosting a party.

Would your chosen size of system cope?

All battery types have risks including explosion, fire and chemical leakage. To keep you, your family and your neighbours safe, ensure your batteries are:

• Installed correctly
• Stored safely (think of closeness to living spaces, exit paths and potential damage to your home and car)
• Regularly maintained.

There are regulations governing the housing of batteries that could add to your purchase costs. Read more on the Battery Safety Guide website.

Solar panels generally have 20–25 year performance and operating warranties. Inverters and battery management systems may only have a five or 10 year warranty. This means you’ll probably need to replace inverters and batteries at least once, perhaps twice, during the life of your solar panels.

If your system breaks down, it could be quite costly to fix. And with no electricity supply from the grid, you’ll have to pay for fuel to run your generator.

You may also have to pay someone to clean your panels, check your system (ideally annually) and service your generator.

When you go off the grid, maintaining your power supply becomes your responsibility. Regular services by an electrical professional are essential.

Minor issues could be inconvenient or possibly result in you using your back-up generator for quite some time. It depends on the level of system support, so some important questions for a potential supplier or installer include:

• How is the product supported?
• Is there someone to call early in the morning or at night for assistance?
• How long might it take spares to come, considering they may need to come from another country?

If you have an electric vehicle (EV) or are considering buying one, charging it creates a high electricity demand (kW) and consumption (kWh). Meeting that extra demand may add a lot to your solar PV/battery set-up costs and the roof space required for panels. The average EV draws around 18kWh of charge to travel 100km¹.

An off-grid home may draw in some potential buyers and deter others, so if going off-grid is appealing to you, consider the following:

• The potential buying pool could be smaller when you come to sell your home
• Even if a buyer is prepared to pay more for an off-grid house, that amount may be less than the total amount of the payback you expected
• As well, check with your home insurer to ensure your home remains suitably insured.

Also, it’s a good idea to check any local council restrictions or estate covenants. These can include restrictions on solar panels on the front of houses, where the batteries are housed and the use of petrol/diesel generators - particularly at night given the potential noise levels.