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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!