If you are in the position to consider alternative electrical power supplies to your home, you have two options, grid-tied or independent. Either way, you need to need to calculator your power consumption before you can decide. For those ready to take on what can be an expensive investment, you still have to work out your usage and how you could supplement your alternative power system. If you are in a remote location on a small farm or back country cabin, the same applies. Lighting, pumps, small kitchen or household appliances all add up.
Here is a simple method to calculate your power usage :
- Make a list of all the electrical appliances you either use or intend to use
- Obtain the wattage of each item from the items product label
(If the label shows only Volts & Amps, the calculation is - Volts x Amps = Wattage (per hour of usage).
- For this list, calculate the number of Watts each appliance uses (per hour)
- Estimate the number of hours you use that item, and then calulate its consumption per day
ie Multiply by the hours of usage with the hourly Wattage for the total the comsumption (per day)
Note that some items are more difficult to calculate such as a fridge, as it draws a lot of power to start the compressor and reach its operating temperature, but little to maintain it. These kind of appliances are usually quoted as an average of Kilowatt hours per year. (In that case, divide this figure by 365(days) for a daily consumption.)
Appliances like a computer draw power differently eg, browsing v's watching a DVD. It's best to use a power monitor to measure the exact power consumption of things like fridges and computers.
From this list, totalise the consumption of all items. Now you know how many watts of power you need to generate per day for what you want to run. Of course you can cheat a little and use a power monitor to help your calculations. Plug the appliance into the unit and it displays the consumption for each item.
Power Calculations
- Each item should have the wattage on its product label
(eg. 60W light globe, 650W microwave). - 1 Kilowatt = 1000 Watts
- Voltage x AMPS = Watts
- Watts are measured on a 1 hour basis.eg a 60 watts lightbulb is 60Watts/hour
- For appliances quoted in KiloWatt hours per YEAR, divide it by 365 for kilowatt’s per day
With these caluculations in hand, you can judge the best way to plan for supplementing either all or some of your power consmption. This is the only way that you can plan either a complete system or a smaller even a DIY solar.
