Grid-Tied Solar Systems – a solar system connected to the utility power grid
Related Terms: Grid-tied, on-grid, utility-interactive, grid intertie and grid back-feeding
Advantages
- Save money with solar panels through better efficiency rates, net metering, plus lower equipment and installation costs.
Batteries are not required so is generally cheaper and simpler to install. - Net metering allows homeowner to put excess electricity into the utility grid resulting in a credit with the utility company. Solar panels will often generate more electricity than what one is capable of consuming.
- Net metering (or feed-in tariff schemes in some countries) develops incentives for the residential solar system.
- Access to backup power from the utility grid (in case your solar system stop generating electricity). At the same time you help to mitigate the utility company’s peak load resulting in an efficient electrical system
Equipment
1. Grid-Tie Inverter (GTI)
The job of the inverter is to regulate the voltage and current received from your solar panels. Direct current (DC) from solar panels is converted into alternating current (AC), which is the type of current that is utilized by electrical appliances. The GTI also synchronizes the phase and frequency of the current to fit the utility grid (nominally 60Hz). The output voltage is adjusted higher than the grid voltage in order for excess electricity to flow outwards to the grid.
2. Micro-Inverters
Micro-inverters go on the back of each solar panel.
3. Power Meter
Most homeowners will need to replace their current power meter with one that is compatible with net metering. This device is capable of measuring power going in both directions, from the grid to the house/house to the grid.
*Contact local utility company for available options…
Off-Grid Solar Systems – Standalone
Advantages
- Off-grid solar systems are less expensive than extending power lines in remote areas.
- A distance of 100 yards or more from the grid. The costs of overhead transmission lines range from $174,000 per mile (for rural construction) to $11,000,000 per mile (for urban construction).
- Become energy self-sufficient. Living off the grid and being self-sufficient is revitalizing. For some people, this feeling is worth more than saving money.
- Energy self-sufficiency is a form of security. Power failures on the utility grid do not affect off-grid solar systems.
Disadvantages
- To ensure access to electricity at all times, off-grid solar systems require battery storage and a backup generator.
- Batteries store a limited amount of energy.
- Battery bank replacement every 10 years
Equipment
1. Solar Charge Controller
Solar charge controllers (charge or battery regulators). Solar battery chargers limit the rate of current being delivered to the battery bank and protect the batteries from overcharging.
2. Battery Bank
A battery bank is a group of batteries wired together.
3. DC Disconnect Switch
AC and DC safety disconnects are required for all solar systems. One additional DC disconnect is installed between the battery bank and the inverter. It is used to switch off the current flowing between these components, important for maintenance, troubleshooting and protection against electrical fires.
4. Off-Grid Inverter
Convert DC to AC for electrical appliances.
5. Backup Generator
Generators run on diesel (recommended), propane, petroleum, gasoline and many other fuel types. (Backup generators output AC, which can be sent through the inverter for direct use, or it can be converted into DC for battery storage.)
Hybrid Solar Systems – combines best the grid and off-grid
Advantages
- Less expensive than off-grid solar systems, backup generator unnecessary and the capacity of your battery bank can be downsized.
- Off-peak electricity from the utility company is cheaper than diesel.
- New inverters let homeowners take advantage of changes in the utility electricity rates throughout the day.
- Solar panels happen to output the most electrical power at noon – previous to time when the price of electricity peaks.
- Capability to temporarily store whatever excess electricity from solar panels in batterie, put on the utility grid when paid the highest rate for kWh.
- Smart solar will become increasingly important as we transition towards the smart grid of the future.
- Utilize battery-based grid-tie inverters. These devices combine the draw of electrical power to and from battery banks and synchronize with the utility grid
Equipment
1. Charge Controller
2. Battery Bank
3. DC Disconnect (additional)
4. Battery-Based Grid-Tie Inverter
5. Power Meter
6. Battery-Based Grid-Tie Inverter