Before reading further, it’s important that you understand the difference between power and energy.
Appliances use power in different ways. Some use large amounts of power and are on for a short time (like a toaster), while others use small amounts of power for longer periods (like a clock radio). When you are living off the grid it is not a bad idea to have a basic understanding of the way each of your appliances work. They are categorised below into sections of the house.
- Stand by loads
- Entertainment – TV and Stereo
- Kitchen – Fridge, Toaster, Kettle, and Dishwasher
- Bathroom – Hair dryer
- Washing and Cleaning – Washing machine, Clothes dryer, Iron and Vacuum
- Heating and Cooling – Hot water, Air conditioner and Heat Pump
- Home Office – Desktop and Laptop
TV – Look for a Star Rating. The most efficient flat screen TVs are: LED, then LCD and finally the plasma.
Tips: When you are looking at buying a new TV for your off grid home make sure you are comparing star ratings of TVs that are the same sizes. Also, keep in mind that the yearly kWh usage on the star rating assumes the TV will be on for 10 hours per day.
Stereo – The power rating (kW) of stereos are often more than what you would use when it comes to the calculating the energy used to design an off grid solar power system. This is because the power that a stereo uses depends on the level of bass in the song you are playing and the volume that you play it. If you are listening to country music with the volume down you will use a small fraction of the power rating.
Fridge – Look for a Star Rating. New fridges are on average 70% more efficient than fridges that are 30 years old. When you are living off the grid you are better off with a new fridge.
With any fridge, if you open the door the cold air escapes. This makes the fridge motor operate (burning up power). So fridges will use more power if they are left open for long periods.
Also, if you have your fridge in a warm room it will use more power than in a cold room. This is because the fridge needs to work harder to reach the desired temperature.
Toaster – Most toasters only use power when the toast is down. They normally use between 1200W and 2400W, but they are only used for a short amount of time. For this reason they actually use less energy than what most people think.
Kettle – Of course you can have a kettle when you are living off the grid. They use power in a similar way to a toaster. Having said that, if you have a fire going you may as well heat your water over the fireplace.
Dishwasher – Look for a Star Rating. The star rating of a dishwasher is far more useful than the power rating when you are planning your off grid system. The star rating assumes 7 uses per week on a ‘normal’ setting.
Hair dryer – If you design a stand-alone power system correctly you can use a hairdryer without any problems. When you have a hair dryer in “hot” mode you use more power than when using “warm” mode. If you like to have your hair dryer blasting away for half an hour, you just need to allow for it when your are doing your electricity usage calculation.
Washing and Cleaning
Washing Machine – Look for a Star Rating. Similar to a dishwasher, the star rating of a washing machine is far more useful than the power rating when you are planning your off grid system. The star rating assumes 7 uses per week using a warm wash.
Clothes Dryer – Look for a Star Rating. Clothes dryers draw a lot of power. If you want one it would be wise to run it when the sun is shining or using only in an emergency, rather than regularly. If you can, use the sun to dry your clothes directly. The sun is a great natural disinfectant too as UV from the sun kills bacteria.
Vacuum – Vacuum cleaners normally draw about 1000W when they are in use. If you can use them during the day it won’t be as big a drain on your resources.
Heating and Cooling
Hot Water – Normally people use solar hot water systems backed up by a gas instantaneous booster when they are off the grid. However, with the price of solar panels reducing, in some cases heating hot water with off grid electricity is more cost effective than using the traditional thermal solar hot water.
Air Conditioners and Heat Pump – Look for a Star Rating. Unlike electric heaters, Air conditioners are more than 100% efficient. With a standard heater, if you put 2kW of electricity in, you get 2kW of heat out. However with an air conditioner if you put 2kW of electricity in you would normally get 3 – 5 times the heat out. This is 300 – 500% efficiency. There are some products that claim more than 700% efficiencies.
When you are looking at air conditioners it is worth remembering the kW rate that they advertise is normally the output power rather than the input electricity. Although it is possible to run air conditioners when you are living off the grid they can push the price of your batteries up if you want to run these units when the sun is down. If you can run them through the day and store the energy in the form of hot or cold air in the house through good insulation, they can be relatively cheap to run when you are off the grid.
Desktop – Desktops use between 30 – 160W. This is a pretty big difference over a few hours. If you are running a disc or running a complicated app or video game they will use more than if you are simply working on your emails. If you can use a laptop, you will be better off from a energy consumption perspective.
Laptop – The bigger the screen, the more power they use. Laptops are designed to be much more efficient so that the battery can last longer (does this sound familiar?) An 18 inch laptop uses less than 20W.