Off-Grid Residence Powered by LE-300

"I must say that despite having wind speeds or 20 to 30 knots all week, and the fact that we mounted our mast onto our upper side-deck, the absolute lack of noise from the turbine is remarkable. We were standing ready to move the whole arrangement into the garden if noise proved to be a problem, and were both relieved and stunned that even when spinning up in high winds (we had a foul Sou'easter yesterday) only the faintest "whooo" could be discerned - and nothing to be heard indoors at all."

Rod McGregor Mann

Written by Rod McGregor Mann, this case study takes you through how this domestic renewable energy project evolved. “At the heart of it are three energy saving things: Our Leading Edge wind turbine set-up, our solar geyser and our brains!” says Rod.  

“I really hope this article 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.”

Our little house is situated on the edge of the dune system and riverine forest of the Kleinemonde River, in an elevated position about 800m from the Indian Ocean, so we do cop quite a lot of weather. Kleinemonde, which means “little river mouths”, looks over the Indian Ocean at around 66m above sea level at 33°32′59″S27°03′00″E. This is significant when you understand that at this southern latitude we are a mere 6.5 degrees above the “Roaring Forties” from where the Coriolis effect drives wind from the Southern Ocean, which is then accelerated by the heating of the interior of our sub-continent: The Karoo and the Kalahari Desert.

Today, as I sit to write, the onshore breeze is 8 metres per second ENE, while the temperature is a pleasant 22 Deg. C. In the central interior the temperature is in the mid 30s and you can be sure that the wind has gathered even more speed and is busily tossing dust devils in and around the Karoo Koppies. 3 years ago, when we stood on our small building plot considering our options, we thought it was just breezy. So why the meteorology? What changed?

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.

We were both driven by the idea that globally, energy is not getting any cheaper – far from it – and locally: our supply from the grid is becoming increasingly uncertain. As our income is likely to decrease in real terms we needed to address how we would reduce our cost of living without lowering its standard. Energy costs are at the heart of everything.

So living in sunny South Africa on a breezy part of the Southern Coast it made natural sense to look at both wind and solar options. Oh boy! What a nightmare. If anyone reading this thinks there is an affordable turn-key solution that you can buy off the shelf to run a regular home with all its gizmos you can forget it. In all likelihood you will be running your place on 220 or 110 AC and everything with a switch on it is completely ill-suited to be run on renewable energy – mostly 12 or 24v DC. Additionally your house wiring will be completely and utterly wrong – even dangerous – for low current green power.

That’s the bad news, but better know that now than have a fast talking salesman – and they are out there in their droves – promise you the world and get you to part with your life savings only to end up with a dud system.

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!