Think twice before going off-grid

As domestic electricity prices are increasing, there is more and more discussion about going "off-grid".

Assuming that you want to maintain a reliable electricity supply to your home or business, then to go off-grid means you have to replace your electricity supply with an alternative. A decade ago that might have been small generators running off motor fuel. Using this option in urban areas would not go down well with the neighbours or the environment.

The popular alternative today is to install solar panels on the roof of your home or business and generate the electricity when the sun is shining. With enough solar panels it is possible (weather permitting) to generate all the electricity you need during the daytime.

To supply the rest of the day you would need to save any excess energy from the solar panels so you can use that electricity when the panels are no longer generating power. The popular way of saving this energy is to install batteries with your solar panel system so the excess power generated can be used to keep the batteries charged rather than passing it onto the grid. These batteries can supply the electricity needed at night and in bad weather.

The size of the panels and the storage size of the batteries depends on your regular power usage and the amount of sunlight you receive over the year. This, in turn, depends on the location of the building, physically and geographically.

Solar panels and batteries are not cheap and don't last forever. You might only get 10-15 years' usage out of your system, so you need to make sure the total cost covers the cost of your grid electricity over those years, plus the interest you might have earned on the money spent on the panels and batteries.

Let me tell you about my experience with solar and batteries.

In 2006 we relocated from Melbourne to live in the northern rivers area of far north NSW. We chose to live in a rural area near Mullumbimby. (No we are not hippies).

Back then the electricity supply in that area was somewhat problematic. This was before the so called "network gold plating" had been applied to this area. It is an area prone to very heavy rainfall (about 3 times that of Melbourne) plus fierce electrical storms that can play havoc with transmission lines. Blackouts were regular, and I liked the idea of not being at the beck and call of the local electricity distributor.

According to my retailer Origin Energy my house should have a 5kW solar array at a likely cost of $9,000 according to Solar Choice. Unfortunately, I didn't have sufficient suitable roof area for a 5kW system.

AGL recommend a 12 kWh battery for a 5kW solar system at a cost of around $15,000. So the total capital cost for the 5kW system with battery would have been $24,000 including installation.

So in 2008, I invested $13,000 in a more modest PV system with lead-acid batteries. In those days the NSW government applied rebates for such systems so it only really cost me $5,000. Lead-acid batteries (like those used in motor vehicles) require regular maintenance ensuring the acid levels are kept topped up and connectors kept clean. Apart from that, the system was terrific! While neighbours had candles in their windows at night because of a blackout, we had a fully functioning electricity system.