Actually, just about everything about how we think about our day-to-day energy consumption and how our small dream home evolved to maximise the use of solar and wind power. And not just for driving gadgets like garden lights. I’m talking about heating and cooling, lighting and communications, garden irrigation and a security system; even how we provide ourselves with a secure supply of potable water in a “renewable” manner. So for us today, keeping a “weather eye” on, well, the weather, is critically important.
We’ve done it so well, in fact, that our home build off-grid renewable energy project earned us a second place in the 2013 “Eta” Energy Savings Awards held recently in Johannesburg – and we were up against a lot of people who were a darned sight more clued up than us. (Including Energy Consultants and Engineers!) And us? I’m a semi retired TV writer and my wife worked mostly in the wine industry; energy boffins we are certainly not.
Our first renewable energy gadget was a solar powered flood light to illuminate our yard. It worked brilliantly for about six months and then the battery failed to hold a charge for more than about five hours, so in the wee wee hours our yard is pitch dark. Lesson one: don’t buy cheap, buy quality.
Enough of the doom and gloom, however, because, as we did eventually find out, there is good news! People like Leading Edge Turbines make well engineered and durable products that do exactly what they say on the box with terrific back up support. The, some might say “modest”, workable renewable energy device we first installed was an LE-300 wind turbine and a locally sourced bank of deep cycle batteries. The turbine came as a deal that included a Turnigy monitoring device, a switch/brake and a black box thing (DL-300 Charge Controller) that fools our batteries into thinking it is another battery but cunningly “dumps” surplus energy to stop the batteries over charging. It also has a couple of lights to indicate what it is up to: charging/floating or dumping. The entire set-up came in at about half the cost the energy company wanted to charge us for bringing a 60 amp supply to our plot – and that immediately ticked the “affordability” box.
Now 300 Watts doesn’t sound like much and the prophets of doom said we would run our batteries out in no time. So we did wonder if we had made a mistake. But a control systems engineer friend worked up a little excel spread sheet calculator that guaranteed that for every device we ran on our power system, we would have the correct cable size connected to it – no wasted energy and no voltage drop. We used this to calculate each and every wire and began adding things we needed item by item. We learned almost immediately that provided each device was used only intermittently and remained aware of the state of charge (the wind speed!) our batteries remained pretty much full all of the time.
We converted all our normal table and bedside lights to take CFL 12v DC lamps (just like the regular energy savers but rated for 12v DC) and ditched the little power units we used to charge our phones, lap top, satellite dish and decoder, wireless internet antenna when we realised that all they had been doing was dropping 220 AC to 12v DC anyway. We used plugs like the ones on yachts and fitted a few “cigarette lighter” sockets to power ad hoc items like rechargeable torches etc. And as said, all these things are used only intermittently and mostly in the morning or evening. And it is during the daytime that the wind blows best. So even if we deplete the battery charge one day, provided we have a breeze, they get topped up before we put them to work again.
Since then we have added a Jabsco 12v irrigation pump, a security alarm system and LED lighting on our deck and LED flood lighting that are triggered by passive sensors. Pretty much all the comforts of home. The Turnigy monitor tells us what’s going on and we’ve learned, as mentioned, to keep an eye on the daily wind speeds. So much for the prophets of doom. And hey, the turbine is super quiet too.
As to our other energy requirements, we cook on a solar cooker, bio mass fuels in a solid fuel stove or an LPG cooker, our water is heated by means of a solar geyser (close-coupled thermosiphon solar water heater) which heats all the hot water we need for baths, showers, washing up and the washing machine and this is all fed by gravity. We harvest and filter rainwater from our roof to give us a backup of 6500 litres.
Our grid connection is now a 20 amp pre-pay supply that we use for our refrigerator, PC and monitor (which doubles as our TV), work tools like saws and lawnmower and we adapted the washing machine to only use power for the motor – it is fed and drained by gravity. Additional lighting is by means of Consol solar-jars and we are now contemplating adding some PV panels (when the costs come down).
Everything we have tried has been added incrementally and we watch the consumption like hawks. The cheapest energy unit is the one you DON’T use! The quantitative results that were examined and verified by the Eta Award people show that our grid power consumption has run consistently at 68kwh per month for the past 12 months at a cost to us of ZAR55.00 per month (GBP 3.95 / USD 6.00 / Euro 4.15). Oh, and we currently have a surplus on our pre-pay meter of around 260 kwh in “the bank” while our monthly LPG bill (cooker and back up high efficiency water geyser 12 LPM for cloudy days) averages about the same as our grid power cost.
This is the solution we tailored for ourselves. At the heart of it are three energy saving things: Our Leading Edge wind turbine set-up, our solar geyser and our brains!
I really hope this helps anyone who feels, as we did, completely flummoxed at the prospect of establishing renewable energy in their homes. You may not go completely off grid or you may go off and live in a cabin in the woods, the trick is to first manage your expectations and your budget. Decide what is a “must have” and then add in the “like to have” stuff. It worked for us!