There are generally three types of solar systems; each has advantages depending on the circumstances of the individual installation. For information about the cost of a typical solar system, please see the Economics of Solar Systems page.
This type of solar power system consists of a relatively large solar panel array and a "grid tie" inverter. Electricity generated by the solar panels is used to partially, or completely, offset any electricity purchased from your power company. While simplest in initial installation and most efficient in power production these systems have one main limitation; no solar power is usable when the utility grid goes down; leaving you in the dark like everyone else during power outages. Grid Tie systems also require careful coordination with the power company. This design works well to reduce your utility bill in an area where there are minimal power outages.
Off-Grid power systems consist of a solar panel(s), a battery bank, an inverter, and various controls and wiring. These systems operate completely independent of the utility company, usually in remote areas. Careful design and usage are necessary to prevent using more power than is being produced and thus, depleting the battery bank. A small generator can be added to cover for times of extra power usage (such as when hosting guests) or during long periods of cloudy weather. This type of system is used for cabins and homes that do not have access to utility power lines. It's also a great way for RV owners to be able to have electricity no matter where they're camped. Solar power on an RV can significantly reduce or eliminate the need for a generator, and the maintenance, smell, and noise, that go with it. Solar is also a great way to maintain batteries on RV's, boats, and automobiles that sit unused for long periods of time. It's also a great emergency back-up power supply for critical appliances such as a sump pump or freezer.
These systems combine the other two types into one "hybrid" system. Solar electricity is used to offset your usage of utility power during normal operation. During a power outage, you can continue to use your solar system to provide power to your home within the limits of your panels and battery bank. The ability to provide power during an outage makes these systems an excellent alternative to a standby generator in many cases. Some efficiency is lost due to the battery bank, and batteries usually require replacement every 6 to 10 years. Advances in lithium ion battery technology are greatly extending battery life but generally at a greater initial cost.
While these systems are the most complicated and expensive, they do provide the convenience of a grid connection with the ability to provide your own emergency power in times when the utility company goes down.