The purpose of this section is to provide a bit of information about parts of a renewable energy system, for those interested in a more in-depth understanding. Complete understanding of this information is not required for you to own one of these systems. If you hire a licensed contractor, they will have all the knowledge required to help you choose a system that meets your energy needs.
- Batteries are a crucial component for an off-grid electrical system. The power that your renewable energy system generates is not used directly — instead it is used to recharge large batteries. For an off-grid system, the available power you have is the amount of power that is stored in the batteries.
- Charge controller
- The charge controller optimizes the voltage and/or current being added to, or drawn from, the batteries. By regulating the movement of voltage and current, the charge controller prevents overcharging the batteries, improving the overall battery lifespan.
- An inverter is used to convert the electrical current from direct to alternating. Battery banks release energy with a direct current (DC), whereas alternating current (AC) energy is required as an input for many standard appliances and modern electronics. AC is much easier to transport over long distances (such as the electrical grid) than DC, as it is less susceptible to voltage drops and requires cheaper infrastructure.
- Essential loads panel
- An essential loads panel is similar to a regular main breaker service panel in your home. During a normal day, you may be powering lights, appliances, and other loads that aren’t essential. During a power outage an essential loads panel directs available electricity to only important loads, such as a wood pellet stove, refrigerator, lights, etc. Since the electrical grid does not work during an outage, these panels require an electrical input from an independent source, such as a battery bank or a generator.
- Net meter
- Through NB Power’s Net Metering Program, the power that your renewable energy system generates can be fed back into the existing electrical grid through a net meter, a special type of meter that will replace your current one. This new meter records the amount of electricity that you use from the grid, as well as the electricity that you produce and send back to the distribution system. You will then be billed for the difference, or net amount of electricity used. Credits from this program cannot be carried forward beyond March of each year.
Grid tied vs. off grid
Grid tied renewable energy systems send the electricity that they generate straight back to the electrical grid through an NB Power net meter. At the bare minimum, these systems require a renewable energy technology (solar panels, wind turbine, etc.), an inverter, and a net meter. These systems contain no form of energy storage, so you will still be dependent on the electrical grid (i.e. you will still lose power during an outage). As a trade-off, these systems contain fewer components, so they have a cheaper initial cost and are less prone to malfunctions. A grid tied system works best in an area with reliable energy infrastructure to help offset your energy needs.
Off grid renewable energy systems allow you to store the energy you produce, and use it to power your residence as needed. These systems require a renewable energy technology, inverter, charge controller, and batteries. Due to the number of components, these systems generally require a larger investment than grid-tied systems, however during outages you will still be able to use the electricity you have produced. Off-grid system owners will need to have space available for storing batteries throughout the winter, and need to perform more regular check-ups to ensure their system is working as intended.
- Note that off-grid system owners must contact the Government of New Brunswick’s Technical Inspection Services in order to ensure the safety of the installation.
It is possible to have a system that incorporates aspects of both off-grid and grid tied systems. These systems normally operate as grid tied systems, but also contain a charge controller and battery bank. During power outages, your appliances will operate using energy stored in your batteries. It is highly recommended for people using these systems to include an essential loads panel, which provides energy to only necessary appliances during an outage. Power generated by your PV panels during this time will be directed to re-charge the batteries instead of the net meter. These systems typically have a high initial cost due to the number of components they require.