Comparisons of Different Types of Solar Power Systems

Here a comparison the various types of photovoltaic based systems shall be shown, particularly grid-tied solar systems, grid-tied solar system with battery backup, grid-tied system with generator backup, and off-grid solar power systems.

  Grid-Tied Grid-Tied w/ Battery Backup Grid-Tied w/ Generator Backup Off-Grid
Typical Return on Investment 7-20% 5-10% 5-10% <1%
Maintenance Required None

Replace Batteries every 5-10 Years

Periodically run generator, typical engine maintenance

Replace Batteries every 5-10 Years, frequent battery maintenance if flooded batteries are used
Average Install Time 1day per kilowatt 2-3days per kilowatt 2 days per kilowatt 3 days per kilowatt
Cost $ $$ $$ $$$
Rebates Available Yes Yes Yes Yes
Power if Grid Goes Down No Critical circuits only Critical circuits only Yes, not connected to grid
Clean, renewable, solar power Yes Yes Yes Yes


So Which Type of System is the Best for me?

This all depends on what your goals are. For the best return on investment, a standard grid-tied system is best. If you want a good investment and peace of mind in the event of a power grid failure, then a grid-tied system with backup makes sense. If you live in a remote area with no local utility power available, then an off-grid system is your only option.

Why is the Return on Investment so Small for an Off-Grid System?

Off-grid photovoltaic systems utilize a large number of batteries to store energy for around the clock use. These large batteries are expensive, and must be replaced every 5-10 years. This extra cost raises the amount of money you are spending per kilowatt-hour that you produce. In some cases the cost will exceed that which the utility company would charge for electricity. However, if you live in a very remote area that does not have local transmission lines, you would have to pay the utility company to install them, which could far outweigh the cost of an off-grid solar power system. Not to mention the environmental benefit of using clean renewable solar energy!