What’s the AC-DC on Solar?

​Solar energy is a “renewable” energy resource. Solar energy used to be subsidised in Australia up until June 30th, 2014. Each year, the cost of solar panels is going down and the efficiency of solar panels is going up which means it is always becoming more viable.

At Freesia Gardens we asked two reputable solar energy companies to quote on a 15kW solar system for our roof. We have 6 air conditioning units on the roof and a couple of skylights but for the most part it is flat concrete space with no summer or winter sun shadow.

Well, solar feasibility is not always as simple as it sounds. If you want to reduce the cost of the solar installation you have to be able to get the panels onto the roof without using a cherry picker. You also want to reduce the length of cable where the solar energy is Direct Current (DC) to the transformer where it is converted into Alternating Current (AC) which you can use in your building. This is leading some solutions to put the DC/AC converter on the roof, rather than in the basement switch room.

You always need a way to get a spare panel onto the roof, without calling a cherry picker. What if a freak hailstorm comes through and cracks a panel?

This makes it difficult for some installations and one company wouldn’t provide a quote for us on OH&S grounds as we wanted to take the panels up the internal fire escape and hoist them onto the roof.

The payback without government subsidies is now more like 14 years on a 15kw system with no batteries for storing power, but the ability to pump excess energy back into the grid.

The problem is that the rate you get for pumping back into the grid is less than a 1/10th of the cost of taking it out of the grid.
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This means we need further innovation in solar to start making it feasible for mid-rise strata buildings. Maybe a shared solar utility across 6 neighbouring blocks?