07 Nov Is off-grid off-limits?
Australian cities have some of the highest solar potential in the world, with insolation values far exceeding those in Europe, Russia and most of North America. Typically, areas of insolation which compares to that of Australia are far from population centres. The image below shows global insolation levels. So why would we use anything but solar power?
According to Energy Made Easy, an average Perth household of four consumes just over 7,000kWh of electricity per year; a demand which could be met with a 4kW system (less than 30m2 of roof space). We have taken advantage of this potential with a rapidly growing photovoltaic capacity which now places us among the top ten solar countries. The problem with solar power is that the sun is strongest during the day when most of us are out and about, and when we all arrive home and need power for lights, laptops, cooking and more, the sun is setting or has already set and the photo-voltaic panels on the roof can no longer provide any electricity.
To date this has predominantly been dealt with by connecting the home energy system to the grid. During the day the solar system provides energy to the grid – becoming a micro power station of sorts. In the evening and overnight the power for the home is taken back from the grid. Until recently connected to the grid in this way has been the most cost effective way to power one’s home as household batteries to store the solar energy over the day for use at night were prohibitively expensive.
This year it marks a breakthrough in battery technology with the launch of the Powerwall by Tesla. This lithium-ion battery is expected to retail in Australia for a fraction of the price of its’ predecessors with first deliveries commencing later this year.
Does this mean we should all get our own home batteries and go “off-grid”? If the grid power we are purchasing is from fossil fuels then from a sustainability perspective this is definitely the way forward.
And what about the costs? Adapting Forbes magazine’s estimation of the cost of using a Powerwall in conjunction with solar panels to an Australian context gives an average cost between 24-30 cents per kWh. The average price of electricity from the grid is 22-33 cents per kWh depending on where in Australia. This means that provided you can come up with the upfront costs to install the system you will break even at worst and have left a few more tonnes of carbon in the ground.
However for those of us with easy access to the grid, by far the cheapest option thus far is still solar power connected to the grid at 7-18 cents per kWh. Unfortunately in Australia this likely means continuing to support the use of fossil fuels unless you opt for 100% renewable energy from your provider.
The low price of solar connected to the grid (and indeed the substantial range in cost per kWh) is heavily reliant on feed-in tariffs which may go up or down over time. And of course as the use of household batteries begins to be more commonplace, the upfront costs of these are likely to go down. So the argument for greater power security over time through the use of batteries in the home is certainly valid.
Tesla is not the only company focusing their efforts on power storage in the home. Nissan and Mitsubishi have developed systems which use your car to charge your house to reduce peak loads or in case of a power outage. In fact, during natural disasters many electric vehicle owners have managed to rig up a connection from their cars to power their homes themselves.
Batteries are definitely progressing in leaps and bounds, far exceeding anticipated advances, and are predicted to dramatically changing the global energy landscape. Watch this space!