Enabling change in our Society, Environment and Economy (SEE)

Direct-coupled solar appliances

– a future mega-trend in solar?

by Bill Gresham, January 2012

What if electrical appliances came with their own solar panel to run them? Well, some already do and I think a lot more will in future. If this idea takes off, the result would be far-reaching and good, both for the householder and the power grid, but maybe not for electricians.

I have just installed a solar-powered roof ventilation fan ($550) to suck hot air from the roof space and thus cool the house (see photo). The solar-powered model costs about $100 more the non-solar model, but would an electrician install a power point in your ceiling for $100? The solar model, of course, draws no grid power. The non-solar model would use peak power.

There is a near perfect match between supply of solar power and demand by this solar-powered fan, but in other cases, such as solar-powered security lights, there is an almost perfect MISMATCH. Obviously, batteries are involved here. Solar security lights have been around for years and the prices are falling fast. They come with a small solar panel, a few meters of wire, efficient LED light bulbs, rechargeable batteries and nifty electronics to control the charging etc. I have installed these not only in the traditional places such as near the back and front doors, but also in places of infrequent use INSIDE the house, such as the hallway and WC. Yes, they look ugly, but I can walk around the house at night with gentle, automatic-operating lights. How many Watts are needed for a wee? Someday someone will market such a light that actually looks like a normal inside light.

Now lets look at other candidates to become Direct Coupled Appliances, starting with the most likely. Pool pumps? How about air conditioners? It is not a big jump from a solar-powered roof fan to a solar-powered evaporative air conditioner. With batteries they could even work into the night. How about a super efficient refrigerator (they exist) with its own solar panel on the roof above it? Television? That’s a harder one, but not impossible.

I suggest that as the driving factors (listed below) become more pronounced, the greater the range of Direct Coupled Appliances we will see in the shops.

  1. Cheaper solar PV panels – the chief game-changer
  2. More efficient solar panels – and thus smaller panels needed
  3. Increasing energy efficiency of appliances – and thus smaller panels needed
  4. Better storage batteries – and thus extended hours of use.
  5. Rising electricity costs – and thus a less attractive alternative
  6. Rising labour costs – and thus greater DIY advantage
  7. Increasing popularity and official acceptance of DIY
  8. Greater interest in reducing grid dependent
  9. Growing impatience with Government inaction.

Direct Coupled Appliances use low-voltage DC current direct from the solar panel – no inverter needed. A short wire takes the power to the appliance (motor, light etc) and results in a simpler, safer and more compact DIY- product. Direct Coupled Appliances lend themselves to mass production, mass marketing and distribution through big shopping chains – such as Bunnings. All these factors exert powerful downward pressure on prices – and thus stimulate demand.

So the effect on the householder is lower power consumption (from the grid) and smaller power bills. The effect on the environment is positive. The effect on the grid is reduced demand – including peak demand.

The growth in Direct Coupled Appliances depends more on the extent that industry sees it as an opportunity and how the buying public respond to their offerings than on public policy settings. My hunch is that it will be like other solar developments – much bigger and faster than official predictions. Perhaps a mega-trend!

Questions or comments?  contact billgresham@gmail.com


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