Hybrid solar: How to kiss the grid goodbye by Jeff Bye

If ever there were a need to develop off-grid power systems it would have to be now, when transmission costs are now up to around 60 per cent of non-solar power bills.

Solar systems have historically been classified into two broad camps – “grid connected” or “off-grid” systems. This distinction has arisen due to historical segments of the market that needed solar to do different things. The vast majority of systems we see around Australia’s towns and cities are grid connected and have been driven by feed-in-tariffs and consumer desires to cut electricity costs and do something positive for the environment.

Off-grid systems have historically been the preserve of regional customers seeking to avoid expensive network augmentation costs to provide power to their remote locations. Off-grid systems are usually a lot more expensive as they require battery storage, more complicated control technology and often diesel backup generators to ensure the lights will always shine. Battery technology has also been a culprit as the memory effect of old-style lead-acid batteries has meant that battery arrays are oversized to ensure the depth of discharge is not high and hence battery life is extended.

An emerging trend though is for so-called hybrid systems which take a little from column A, and a little from column B. Such systems could either be described as an off-grid system which uses the grid as the standby generator or a grid-connected system with some added battery storage. Either way, these systems don’t require expensive diesel generators since the grid provides that service, and the size of the battery arrays can be downgraded as the cost of back-up power using off-peak grid electricity is much lower than that provided by diesel generators.