29 August 2017
Go off the Grid
Hacks for going off the grid.
Learn how to make yourself less dependent on Eskom power and more independent by ‘going off the grid’ with power-saving options, generators, solar heating systems and solar power systems.
One of the easiest ways to save on power costs is not to have to use it in the first place. Here are some simple ways in which to save on power consumption and which in most cases involve a ‘one-off’ expense:
- CFUs – Compact Fluorescent Units use far less power, generate less heat and last much longer than incandescent bulbs.
- Correct hot-water geyser setting – water that is too hot wastes both electricity and water. More energy is used to heat it up, and more cold water is used to cool it back down. Overly-hot water is also a danger in a household with small children. Rather set the thermostat to South Africa’s standard, which is 55°C, and perfectly adequate.
- Double-glazing – double-glazing is a ‘one-off’ cost that has proved effective in keeping warmth in during winter and heat out in summer.
- Geyser blankets – these are exactly what the name implies, they are wrapped around the geyser to help reduce heat loss.
- Lag those pipes – lagging your hot water pipes will help to keep the water hotter as it travels through the pipes to the bath, basin, sink or shower.
- Seal gaps – self-adhesive sponge sealing strips (available from Mica stores) applied around doors and windows (and supplemented by a draught-excluder at the bottom of the door) will help reduce cold air entering in winter and hot air entering in summer.
- Shade trees – shade trees planted at specific spots around the home will provide cooling shade during the hot summer months, reducing your cooling costs.
- Switch that geyser off – geysers are fitted with a thermostat that switches it on and off when the water in it cools or reaches the selected temperature. It switches on when a hot-water tap is opened. So while you are at the office, the thermostat is switching your geyser on and off. So turn it off when you leave for work in the morning and on again when you get home in the evening, for a couple of hours before you bath or shower. There are geyser timers available (very much like your pool-pump timer) so you can turn the geyser off overnight, and have it switch on again an hour or two before you get up in the morning.
- Thermal insulation in the roof space – this is laid on the upper surface of the ceiling panels between the trusses and is available in rolls or in a loose-pack form. It helps keep the home cooler in summer and warmer in winter.
- Tint those windows – if you have paving outside a north-facing lounge window, or large north-facing windows, the sun’s rays either reflect off the paving and/or come straight into through the window and can significantly raise a room’s temperature. Window film, available in a range of densities, blocks out the worst of the sun’s rays and infra-red radiation, and can keep a room and home significantly cooler than it would otherwise be.
In this feature we are looking at generators that are more likely to be the choice of homeowners for domestic use.
In order to avoid dealing with a massive fuel bill every month, a generator is best used only as a back-up for when your off-grid solutions are not generating much electricity because of days of full cloud cover or if a fault develops and you need to substitute with a generator for a day or so.
First of all, some cautionary tips:
- Make sure that when selecting a generator, that you are fully aware of exactly what generation capacity it has, and how this translates into actual usage. For example, if you use multiple appliances you will need a generator that will be sufficient enough to power all of these at once.
- The only people legally able to make changes and/or work on your home’s electrical system are qualified and certified electricians, so unless you are qualified, never attempt to connect your generator into the home system.
- Always follow the manufacturer’s operating and safety instructions to the letter provided with your generator.
- Avoid disrupting your neighbours with constant lound noise by running a generator late at night.
- Running any alternative power sources, it is good to check with your local authority to ensure that whatever you plan to do meets local by-laws and other regulations.
- Always check that your generator’s fuel tank is topped up; there’s nothing quite like the dismay you will feel as the generator splutters to a halt just before the kettle has boiled.
- Generators are available in a range of power outputs. You will need to match your purchase to your needs; in fact, it is probably better to go for bigger rather than the bare minimum, a little excess capacity is better than not enough.
Solar Heating Systems
Should you be considering this option, here are some points you might consider. Flat panel collector or evacuated tube collector. Both types are compatible with low or high-pressure systems, but be specific (having discussed your requirements with the contractor), exactly which one is best for you.
A flat panel solar water heater is an insulated glass-covered box containing copper tubes that are attached to a black-painted sheet metal absorber. The sun’s rays heat the metal absorber, which in turn heat the copper pipes, and hence the water circulating in them. That water is part of the home’s water system so after it is heated, it ends up in your bath, shower, basin or sink.
In place of the water-carrying copper tubes, this system has evacuated glass tubes with solar absorbers. These collect the sun’s energy, heat the absorber inside the vacuum tube, which in turn heats the heat transfer fluid inside a copper pipe enclosing heat transfer fins. These conduct heat very efficiently, so the heat transfer liquid heats the water ready for use.
Both types operate along the same principles, as the collector (heating unit) is mounted on a north-facing roof or in an elevated area selected for its high exposure to direct sunlight (so be aware of trees and/or neighbouring building or other factors that might put your new investment in the shade. The collector’s ideal angle is about 45° and facing north. The unit is connected to a hot-water cylinder either above the collector, or mounted separately, or in the roof space.
Solar Power Systems
Solar panels, known as photovoltaic (PV) panels, convert sunlight directly into DC electricity that can then be stored by charging batteries so you can then have power during the night when the panels are effectively ‘off’.
Solar power technology is advancing all the time, what with Elon Musk and others putting a great deal of effort into solar panels, but also alternatives, such as roof tiles that will do the same job.
Currently, however, the most common units are the PV panels we often see on the roofs of homes and businesses around the country.
The same principles apply as do those to selecting the right generator, and selecting the right position and angle for a water-heating panel.
- Decide what power you will need to go off the grid, or adopt a ‘grid-tied system’. You are looking at what you will want to operate, their starting and running power requirements and so on.
- The same requirements that applied to mounting a solar-heating panel apply here as well.
- Ensure that you cost in the batteries… they are expensive and you will also have to cost in the contractor’s fee and any other registration or other costs the local authority might require.
Generators are extremely useful as a power-supply backup during blackouts and also as a supplementary source when weather conditions or other factors reduce power output from other sources such as solar.
Solar-powered garden lights like these don’t provide massive illumination, but can be useful to provide some deterrence to trespassers at night.
This security light over a garage is connected to a PIR (passive infrared) detector and is triggered by movement in front of the door; it is powered by a small solar panel on the other side of the garage.
Solar photovoltaic panels convert sunlight into DC electric power but do not work at night and can be less efficient depending on cloud cover. Having said that, they are a useful source of clean, sustainable power.
The wind has been used for hundreds of years to pump water out of the ground, power windmills to grind grain, and huge wind turbines are across the world, generating power.
The good news it that small turbines for domestic use are readily available and produce cheap, clean and sustainable energy.
Of course, it’s not always blowing, and sometimes it’s blowing less than optimum anyway, but used in conjunction with other forms of sustainable energy. Wind turbines are a very attractive source of electricity generation. Wind turbines have their own requirements if they are to operate with maximum efficiency.
High up in the atmosphere where there is nothing to impede the movement of air, the wind blows along unimpeded. The closer one gets to the ground, however, so mountain ranges, hills and forests begin to slow it.
So you need to ensure that any wind turbines you install are positioned where trees and buildings won’t slow the wind to the turbine. That means that they need to be mounted high up either on a roof or on a tower or tall pole.
This is why wind generators are not so common or so often recommended for built-up urban areas or areas with streets heavily lined with large leafy trees; they slow the wind and also make it more erratic, leading to gusting and constantly changing direction.
You should approach your local authority for guidance and the necessary permissions.
As to the wind speed required, experts reckon a wind speed of at least 16km/h is the minimum.
Apart from actual size and output, wind turbines are available with either a horizontal shaft such as farm windmills which have a fin sticking out the back which turns the whole unit so that the blades face directly into the wind.
The other version has a vertical shaft and the turbine spins like a child’s spinning top. This version is independent of the wind’s direction and is often recommended for areas that experience wind that frequently changes direction. The other advantage of this version is that all the working parts are more easily accessible for servicing.
When we think of hydroelectric power, we usually think of massive dams such as Kariba or the Hoover Dam in the US.
While this power source is not common and is probably virtually unknown in urban areas, if you live on a farm or smallholding, or plan on acquiring one, and you have a perennial stream running through it, it can be worth while thinking about hydroelectric.
Power output depends on the fall and the amount of water, but as an example, a stream with a fall of 1.5m and a flow of 130ℓ/sec can generate as much as 1kW of electricity. A larger stream and greater fall naturally means more potential, but this depends on topography and other factors so as always, call in the experts.
A small stream can generate renewable electricity, consistently, cleanly and at a price that can rival or even beat solar or wind.
A solar water heater can reduce your monthly geyser bills quite substantially.
Small hydroelectric units available and provided you have a stream with sufficient fall, you can generate a substantial amount of power to light your home – though this system is far more likely to be found in a rural rather than an urban setting.
Even a small wind turbine like this can make a significant dent in your monthly energy bill. It is non-intrusive and provides clean, sustainable electrical power – and being near the sea, works hard and really earns its keep.