Maybe. Many older homes were not designed or built with energy efficiency in mind. When you purchase and install a renewable energy system for your home, you become your own power company, so every kWh (kilowatt-hour) of energy you use means more equipment (and hence more money) is required to meet your energy needs.
Any appliance that operates at 240 VAC (such as electric water heaters, cook stoves, furnaces and air conditioners) are expensive loads to run on solar. You should consider using alternatives such as propane or natural gas, and solar water heating for water/space heating or cooking, evaporative cooling (good for hot and dry climates) instead of compressor based AC units and passive solar design in your new home construction if possible.
Refrigeration and lighting are typically the largest 120 VAC energy consumers in a home (after electric heating loads) and these two areas should be looked at very carefully in terms of getting the most energy efficient units available. Great strides have been made in the past 5 years towards improving the efficiency of electric refrigerators/freezers.
LED lights use 10-25% less power than CFL lights, and closer to 50% less power of an incandescent light for the same lumen output (brightness) and they last ten times longer. LEDs are now readily available at your local hardware or discount store. If you plan on having a renewable energy system with a battery bank, consider using LED lights that can be powered directly from the DC voltage of the battery bank (without the use of an inverter, which adds 10 to 20% loss of electricity).
When it comes to renewable energy systems, for every dollar you spend replacing your inefficient appliances, you will save three to five dollars in the cost of a renewable energy system to run those appliances. So you can see that energy conservation is crucial and can really pay off when considering a renewable energy system.