04 Jul The demand for energy
Globally, solar power systems are experiencing the greatest level of growth of all renewable energy formats – in both investments and in share of the energy mix. Photovoltaic prices are continuing to tumble with production levels by the major players like China still buoyant. In fact, solar PV panels are expected to continue flooding the international markets over the next three years, further pushing prices down and making renewable generation increasingly more competitive. Monitoring the developments will become more important over the coming months.
As we know, the harnessing of energy from the Sun has been around a long time. But of more recent interest are the technological advances in how to capture that energy by storing it. After all, we are limited in sunshine hours each day and in our modern environment of 24 hour electricity, the source of energy requires special considerations.
We are, of course, talking about an alternative energy source – that which is renewable and presumably, never runs out. Solar radiation is, however, variable and intermittent. The sun will shine but it won’t shine constantly, and consistently. On average for example, we’re looking at 4.5 hours of sunshine a day. The highest output occurs during the Summer and drops over the Winter months.
Our solar energy thinking for the future therefore has a fundamental starting point. It is based on the principle that the supply of this energy will be the determining factor in how we set up our infrastructure and utilize it – or consume it. This is the complete opposite to the existing utilization, or consumption, of diesel-based energy because fossil fuels are acquired on the principle of demand. Our whole lifestyle revolves around satisfying a 24 hour demand for electricity. So to satisfy this daily demand, we can simply buy the required amount of fossil fuel – and meet that demand.
Our future harnessing and use of solar energy, on the other hand, will be determined by the supply of it. The infrastructure involved in capturing it (solar PV panels), storing it (battery technology, hydro, gas, thermo), converting it (inverter technology), and distributing it (smart grid network systems), all represent a revolution from demand driven electricity – to supply driven electricity.
The stages in between capturing the Sun’s radiation and consuming solar-powered electricity can be broken down into basic components of storage and conversion. Solar energy falling onto PV panels, for example, begins a process of conversion into DC power and through inverter technology, is eventually transformed into AC power – the common form of power that drives everyday appliances, equipment, and machinery. This transformation (or inversion) is necessary to make solar energy compatible with our distribution network system – or grid.
As a result of the variable and intermittent nature of sunshine, the available hours must capture enough energy supply to be stored to make up for the non-sunshine hours. Storage is crucial for a distribution network to supply electricity 24 hours a day. When we talk about storage, we’re talking about ‘banking’ a reserve of energy that must be kept ‘on tap’ for use when we need it. And this method of storage and size of solar panel installations will depend on a variety of factors, including the underlying question of how much it will cost.
Published in the Cook Islands Herald on 4 July 2012.