Let us 1st discuss some electrical appliances that does NOT go well with a solar system, and these are: • Traditional air conditioners • Traditional electrical geyser • Traditional stove Traditional air conditioners Traditional air conditioners in a normal household will be the biggest consumer of power by far. The amount of power it uses is more than what all the other electrical equipment will use in your home. Your option here will be an evaporative cooler. They use 10 times less power than a traditional air conditioner. The reason being that an evaporative cooler is essentially a glorified big fan, with a small water pump. The modern evaporative coolers have a DC motor for the fan, thereby further reducing power requirements at lower speeds. The old evaporative coolers had AC motors with a resistor to lower its speed, but the power input requirement does not reduce for lower speeds, thus always using maximum power. One not so obvious use of an evaporative cooler is that it can be used in summer (with pump/cooling off) before sunrise to replace the hot air in the house with the cooler air from outside. Once the sun is out and temperatures outside rises, switch on the pump/cooling. In winter, the opposite can be done. When the outside temperature is at its hottest, switch the evaporative cooler on (with pump/cooling off) to replace the cold air in the house with the hotter air from outside. Turn the evaporative cooler off after that. In summary, if you want to keep your traditional air conditioners, do not consider solar. Traditional electrical geyser Using a traditional electrical geyser may be feasible in summer, but not so in winter. Reason being that in summer the water is by default lukewarm, and the power required to keep the water warm is much less than that in winter. In summer, the daylight hours are also longer. An alternative is to use 1 or 2 gas geysers. The modern ones work well and does not have pilot flames anymore. It uses a battery to create a spark as soon as a warm water tap is opened. One need to consider that such an installation needs to be done by a certified installer, as some home insurance policies will require that from you. The downside of a gas geyser is that the warm water is not as warm as the water in summer, as the water simply passes through heating flames to heat the water. Thus 10-degree water warmed by 50 degrees gives you 60-degree Celsius warm water in winter. In summer the water will be substantially warmer, probably around 75 degrees Celsius. Controlling a shower temperature with a gas geyser is also trickier. You usually open the warm tap fully and control the temperature by adjusting the cold tap only. In summary, if you want to keep your traditional geyser, I suggest that you keep it off at night. But you are going to spend more money on a bigger solar system for sure. It will cost you much less to install a gas geyser. One key problem with an electrical geyser is that you will not be sure when it is off or on during the day, which will make your power management task difficult. Why? Is it safe to put the stove on at this time without overloading the system? Traditional stove An electrical stove is a big power guzzler. Although not as bad as a traditional air conditioner. That is because unlike a microwave, it is normally used for extended periods of time. If you consider a gas stove, consider one that is all gas. SMEG makes quality gas stoves. You still connect it to an electrical outlet, but it only uses it for the internal stove fan and for the automatic spark when you use a plate. Most other gas stoves you buy are not all gas. The oven portion is normally electrical while the plates are gas. These models are slightly cheaper. Another advantage of gas is that it is instant on and instant off. Cooking a similar pot of water on an electrical plate can take 10min, whereby on gas it is 3min. In summary, if you want to keep your traditional stove, you are going to spend more money on a bigger solar system. It will cost you much less to install a gas stove in the long run. Dishwasher A dishwasher is a must have luxury for most households. Luckily if you plan it right, most households only have to use it every other day. But use it around midday and on sunny days. So, check tomorrows weather. You may have to delay until tomorrow’s sunshine. Then there is the matter of Energy Ratings that are nowadays attached to larger power consuming devices. Manufacturers sometimes manipulate this so that they get the most beneficial score for a specific washing cycle for a measured period. It turned out that on our dishwasher it was the 3hr cycle where they get the best Kw rating over a period of an hour. We use the 45min cycle. It consumes more power for a measured period of an hour but uses much less power overall than the 3hr cycle. And it washes just as clean. They simply spread the power usage over time to get the best per hour score. Ridiculous. Other appliance considerations Items with medium to high power requirements. But used for short periods only are: • Microwaves • Toasters • Hairdryers Items with low power requirements are: • Medium sized water pumps (up to 1kW) • Evaporative cooler • Fans • Fridges • Deepfreezes • Washing machines • Icemakers • Slow cooker • Lights (replace with neon or led lights) Do not use more than 1 high power appliance at the same time. Use you washing machine for instance only from 9am in the day. Refrain from using your high-power devices at night. Use your power-hungry devices between 9am and 2pm, as you need to build capacity for night ours in you batteries.
Deur: Johan Swart.