Grid-Tie systems are the most popular option for urban home and business solar power installations in Ontario. The generous Feed-In-Tariffs (MicroFIT/FIT) make it more cost-effective to sell power to the grid than to use or store it yourself.
In a Grid-Tie MicroFIT setup, the direct-current (DC) solar power generated by the system is converted to alternating-current (AC) electricity by an inverter. The power is then sent through a separate, dedicated meter directly to the local power grid. Because MicroFIT/FIT systems do not store power, they do not use batteries.
Under a MicroFIT/FIT contract, your local power authority pays you for the solar electricity you deliver to the grid at a premium rate (80.2¢/kWh) guaranteed for 20 years. Your household or business continues to use electricity from the grid, paying your local utility for the power consumed.
If Feed-In-Tariffs are not available where you live, you may choose to use solar power you generate to reduce the amount of power you draw from the grid. By using less power, you can lower your electricity bill. Depending on the local utility, you may also have the option to sell any surplus power back to the grid at the going retail rate. This approach is known as net metering and may also be used in conjunction with battery banks and/or an emergency battery backup system.
Off-Grid Solar Power Systems are used when access to the grid is unavailable or prohibitively expensive. Off-Grid systems use deep-cycle batteries to store power for use when the sun is not shining. Charge controllers ensure that the batteries do not get overcharged. Inverters convert the battery’s direct-current power to the alternating-current power used by most households. Some applications use DC power directly, which keeps the system simpler and improves efficiency.
Given the additional cost of battery banks and the generous MicroFIT subsidies available for Grid-Tied solar power, Off-Grid systems are generally not cost-effective where grid power is available. For remote locations like islands, cabins, and farms, however, and for simple Do-it-Yourself applications like garages or boathouses, an Off-Grid solar power system can be an effective and ecologically sound option.
