In general, household power consumption is measured in terms of kilowatt-hours. A kilowatt-hour denotes the level of energy required for powering a 100-watt device for 10 hours or a kilowatt device for one hour. To determine how many power stations your home needs, you should know how many kilowatt-hours you consume. You can get to know this number from your monthly electricity bill. Even, your bill may show the statistics of power usage during the previous months. According to the Energy Information Administration of the USA, the average American home consumes 901 kWh of electricity per month. Otherwise, the approximate value is 30 kWh per day. Batteries in power stations are designed for producing a particular voltage. They are also rated for a particular number of amp-hours. For instance, when you take the case of a 400 amp-hour battery, it can supply 4 amperes of power for 100 hours. The voltage of the battery is fairly constant they say.  Nevertheless, a voltage decreases gradually as the battery discharges. To judge the energy capacity of a battery in kilowatt-hours, you can multiply the operating voltage by the amp-hour rating and divide the result by 1000. So, you should remember these things when you buy a power station to power your home.