Think twice before going off-grid

My annual electricity usage cost, excluding the supply charge, was about $2,100 per year. So as long as the 5kW solar system lasted for 11 years without any costly maintenance and ignoring the time value of money, then it would have been a breakeven deal.

My more modest solar system worked well for the first two years when the inverter packed up. The inverter converts the DC voltage from the solar panels and batteries to usable AC for the house supply. It is the most important part of the system, so without it my solar and battery system was useless. It took 28 days for the supplier to obtain a new inverter from Germany and install it. Fortunately, we were still connected to the grid and, also fortunately, there weren't any blackouts during that period.

If we had gone off-grid we would have been in serious trouble, having to go out and hire a generator (or buy one) and get it connected to the house ring mains.

Perhaps taking 28 days to remedy a faulty part of the system was excessive. But I believe inverters are renowned for failing.

So by all means install solar panels and batteries but make sure they are cost effective. That is producing cheaper electricity over their lifetime than you can get from the grid. These solar systems need constant maintenance, particularly the solar panels that need regular cleaning to maintain energy output levels.

But I strongly recommend against disconnecting from the grid entirely. You might save some supply charges (about 16% of the total bill on average) but you could be at the mercy of a flaky inverter.