Pick a system based on what you need rather than profit and loss

At least that’s the theory. The problem arises when you consider an entire nation doing the same thing at the same time. Thanks to abundant sunlight and detached homes, Australia has one of the highest usage rates of residential solar panels in the world. Somewhere in the area Four out of 10 households have them.

On the country’s main grid, small-scale systems produce 15 percent to 20 percent of electricity during the summer months. For a brief period before noon Saturday, when renewable energy provided 79 percent of the power, rooftop panels accounted for more than half of total generation.

When all these modules work simultaneously in the middle of the day, the result is often excessive power. Instead of getting paid for the electrons they provide, generators get paid for it; This is something that currently occurs about one fifth of the time during daylight hours. Shifting such fines from professional services to homes is a politically risky move, but the sheer volume of rooftop solar means it is inevitable.

Since the beginning of July, people in NSW have been exporting approximately more than 6.8 kWh of energy per day to the grid during the midday solar peak. having to pay for the privilege. According to a back-of-the-envelope calculation, my colleague might be paying $130 a year for his exports, which would reduce the promised $400 income by almost a third. The solar tax is likely to rise further as home production continues to rise and the glut deepens.

There are ways to avoid this punishment. Adding a home battery allows you to shift your exports to the evening peak when the sun sets and prices move back into positive territory. Better yet, buy an electric vehicle and connect it to a two-way charger that allows it to feed into the grid; its battery is much better value than the standalone version and you get a car as part of the bargain.

There are also automated home energy management systems that use software and apps to move your daily usage to higher sun hours, or even turn off your panels’ grid connection when it starts to look costly to export.

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From the perspective of the whole country, such a large resizing may be a good thing. A growing number of studies in recent years have argued that it is cheaper to achieve a clean grid by connecting excess wind and solar power and shutting them off when there is too much generation, rather than installing smaller amounts of battery-backed power.

The problem is that very few commercial players will be willing to install such money-losing generators; but less complex and cost-sensitive than utilities, households may be ideal providers of capital.

Still, all of these considerations point to choosing a system that’s sized for your needs rather than profit-and-loss estimates on your utility bills.

When you turn your home into a power plant, you change your role from customer to speculator in one of the most volatile, brutal commodity markets on the planet.

Electricity buyers and sellers should be careful.

David Fickling is a Bloomberg Opinion columnist covering climate change and energy. He previously worked at Bloomberg News, the Wall Street Journal and the Financial Times..

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