One Family's Story of Energy Independence

Writer’s note: This post is the second in a series that showcases the humble efforts of individuals to do their bit to prevent further global warming. After exploring a stand-alone solar-powered car, we’ll now look at a grid-shy solar-powered property.

Ben and Lena don’t do things the way other folks do. Other folks don’t buy 20 steep, wooded acres and just move onto them, with no power or running water. Other folks call architects, builders, plumbers and electricians, and tell them to create a home. Ben and Lena called their friends, sat around a campfire, drank chai tea and discussed how to live in harmony with the land. Then they all went to work.

Ben, Lena and their son Elwin live in the hills skirting Adelaide, the capital city of South Australia. With the help of WWOOFers, family and friends, they are gradually creating their own little piece of heaven. Numerous sheds and a straw bale hut have grown on the land, like toadstools. Five years ago they installed an off-the-grid solar-power system.

I spoke with them recently in Ben’s earthen-floor office at their property, about their stand-alone set-up. Lena told me about the decision-making process that culminated in their choice of energy for a sunburned country.

In this climate, sun is what we have most of – we don’t have a lot of water; we don’t have a lot of wind – it’s a hot, dry climate and most of the time it’s sunny. So we figured that photovoltaic cells were probably the most sensible electricity source for this climate. Also, being a remote property, there was going to be a lot more effort and money involved to connect to the grid than to have a battery system. So we thought we needed to be self-sufficient and have a stand-alone system. It was a very pragmatic decision. It doesn’t make sense to be connected to the grid.
Ben added his thoughts.
It’s also a piece-of-mind thing; it’s a real satisfaction thing. We know that all of the power that we’re generating is coming from sunshine
It would cost $10,000 to finance a new transformer and cables to bring electricity in, from the existing public line, to their home. Ben and Lena’s stand-alone system cost them less than $7,000. Unfortunately, however, commercial stand-alone outfits don’t come with such a low price tag. $20,000 to $30,000 might give the regular consumer a system that will satisfy their needs. The math adds up for Ben and Lena, partly because they were able to research, plan and build the system themselves, with a little help from their friends. But if their infrastructure cost increased fourfold, it may have made them think again.

What’s he building in there?

Neighbors may have wondered what was going on when a small shed with a shiny, slanted roof, popped up on Ben and Lena’s land. The solar system is housed in a small, purpose-built shed, Ben explained.

Normally people put their panels on the roof of their house. But because there was nothing on the property, one of the first things we did here was set up a solar system. We wanted the power to run all our construction equipment so that we could build, and we didn’t want a petrol generator.

We built a little solar shed and we used the panels as the roof. I wouldn’t recommend that to others because there’s too much solar heat coming through the glass. All the electrical components and the batteries prefer not to be hot – it makes the system inefficient.

We have set up our panels so that they’re at 45 degrees from the horizontal, facing due north to catch winter sun. Optimum power results when the sun is perpendicular to the panels in both planes. We would love to have a system with movable panels, winter to summer, because the optimum angle in summer is very different to the winter angle. However the mechanism for this would be very costly.

He went on to describe the components of a system that provides enough electricity for their meager needs, which do not include a dishwasher, plasma TV or central heating.
Battery bank
The solar system comprises four panels that charge two lead acid batteries. They are deep cycle lead acid batteries, which means that they’re designed to be drawn down quite low in charge then charged up again. They’ve got extra acid above the plates so that if the liquid level gets low, there’s still enough to cover the plates. That’s crucial in lead acid batteries.

We’ve got a 24-volt DC system and there’s a little regulator that regulates the amount of charge. We use some of the power as 24-volt DC to power lights and we also invert some of it to 240-volt AC, which is standard in Australia. We can use standard household appliances if we use the inverter.

Lena explained the household ramifications of a prudent power set-up that links them intimately with their limited resource, giving them a unique perspective on electricity use.
We use less power. Because we don’t have unlimited power, we think about the appliances that we buy and how often we run them. We tend to be frugal with things that use electricity. So we do things like switch off lights when we don’t need them; use the mortar and pestle rather then the food processor; wash our clothes less often; and wash clothes in cold water.
Good news
Solar power made financial sense to Ben and Lena, but it came with some added benefits. Ben talked about the positive characteristics of their system.
You don’t get any power bills. There’s an initial set-up cost but then there are no bills. Our panels will last for about 20 years. And if we look after them, the batteries will last for about 10 years.

When there’s a power blackout, we are protected. Of course our own system can go down, but it’s pretty reliable because it’s much less complicated than a power grid. The grid is an inherently complicated animal; things go wrong and it causes blackouts.

We put all of our cabling underground so there’s no sign of any electricity. There’s the solar shed itself and then just lights, power points and switches; there are no cables to be seen anywhere, which is really nice.

Storing electricity in a battery is not the most efficient method, which means Ben and Lena lose some of their sun-power. However some energy loss is prevented because of the short lines of cabling from the power shed to their house. When compared to a grid that spans hundreds of miles with cabling that “leaks” a good portion of electricity, Ben and Lena are getting more “bang” for their power generation buck.

Also, losses are prevented when they use 24-volt DC for their lights. Inversion from DC to AC results in energy loses, so in a minimalist system where efficiency is key, wiring lights to DC works well. Ben explained that there is no noticeable difference in output between lights that run on AC and those that run on DC.

Not-so-good news

Power independence is not all chocolates and roses. Ben went on to discuss the drawbacks of the system.

We only get power when the sun’s shining. If the sun isn’t shining, then we don’t get any recharge. If we get a week of cold, wet weather in the middle of winter then we can have real shortages of power.

The only thing that runs winter and summer is our fridge. We’ve got a very efficient little fridge, and that’s generally OK any time of the year. But we’ve got to be really careful of other things. We can’t have too many things on for too long, and any one appliance can’t use too much power.

Big electric motors like cement mixers are what trouble our system and that’s all based on the capacity of the inverter that we’ve got. If we were running DC, there’d be no limit - we could run a huge DC motor (because there would be no need to invert the power before it could be used). DC power is a way around the big appliance limitation.

Many of us in the city might complain about the cost of our electricity or the policies of the electrical company that supplies us with power. But we’re always relieved when the company’s electrician pulls his van up in front of our house to magically fix any problem we report. Ben and Lena can’t rely on the friendly “sparky” in his van, however their vast network of friends and relatives, nurtured through communal celebrations and workdays on the property, includes enough electricians to support their needs.

Clever friends are part of their system but cold, hard cash is another, inescapable part, Ben explained.

Our system has a finite life so the batteries are the first things to die. They become less and less efficient at storing and giving power. So eventually we’ll reach a point where, for the amount of energy that’s being put into these batteries, they won’t charge up fully and we’ll only get a small amount of power out of them before they’re flat again. We’ll get to a point where we’ll say, OK, time to buy a new battery. Our batteries weigh about a quarter of a tonne and they cost about $1,000, so it’s a significant expense.

Then in roughly 20 years, we’re going to have to replace the panels, and that’s the biggest expense - that’s just the way it is.

Impact on the planet

One might think a solar-powered man would be a one-eyed supporter of solar panels; however Ben has some rather pragmatic thoughts on the embodied energy in his system, compared to what his more conventional neighbors use. Embodied energy is the total energy required to manufacture and transport a product to its final destination. It takes into account environmental and social impacts on the planet.

The solar shed nestled in the Australian bush
The solar panels, batteries, regulator and inverter all have finite lives, but the two that definitely have the shortest lives are the batteries and the panels.

Solar systems are improving all the time, but there’s a lot of embodied energy in silicon, which is the key component of solar panels. They’re trying to improve solar panel technology to have thinner and thinner silicon layers, because that’s the biggest inefficiency.

Lead acid batteries are recyclable. Exide Technologies, the company we bought them from, say in their brochure: “Over 97 percent of the battery is recyclable. All lead and plastic components are able to be reprocessed by Exide at the end of your battery’s usual life.” So that’s pretty good.

Exide is an Australian company, and one of the reasons we went with them was that they make batteries in Adelaide, so we went there ourselves with our car and trailer and picked up the “ginormously” heavy batteries. (This resulted in less transport miles than if the batteries had come from one of the larger, more distant Australian cities.)

When the batteries are dead, we will take them back to Exide and probably buy some more from them. Maybe they’ll take a bit off the price of the new batteries.

The recycling of the batteries is pretty good, but just because you can recycle something doesn’t mean that you haven’t used a lot of energy when you’re recycling it.

In terms of embodied energy, the grid makes a whole lot of sense because storage is such an issue. The grid’s in place and it effectively transfers power. What makes sense to me is lots of people generating electricity, but not storing their own electricity; they’ll just generate electricity to feed into the grid. If someone uses more than they generate, they pay a bit; if they used less than they generate, maybe they’ll receive a bit. People would collect all of that energy in batteries or in something else. There are all sorts of ways of storing energy; it doesn’t have to be in batteries. For example water could be pumped up to the top of a hill and then run through turbines at night (transferring that energy for use in some other way).

One can imagine a turbine slowly tumbling on its axis, up the hill from Ben and Lena’s house, powering their winter lights after the sun has slipped below the hills and out to sea. With their will to live sustainably, and their readiness to take unconventional risks for the environment, anything seems plausible.

Ben left, with as much haste as Ben cares to muster, for his job guiding tourists around a wildlife reserve; Lena strapped Elwin to her back and plodded down the hill to put the chickens in for the night. She talked about foxes and herbal remedies; the impact of parenthood; and the benefit of socializing her son with WWOOFers from other countries. The hum of the solar shed behind her was softly lost in the sounds of the Australian bush at dusk.

Disclaimer: Neither the author nor the subjects of this article have any affiliation with Exide Technologies.

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  • Posted on Nov. 19, 2007. Listed in:

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