Solar photovoltaic (PV) technologies convert the sun’s radiation to an electrical current that can be used to power a home or business. For customers that are connected to the electrical grid, these systems will push excess power onto the grid for which the owner receives a credit.
For homes without grid power or those looking to have a more secure power supply, PV systems are connected to batteries that store excess electricity. The electricity generated by a PV system can power lighting, household appliances, mini-split heat pumps, electric vehicles, and countless other electrical consumers.
PV systems are commonly roof-mounted due to economics. Using a roof eliminates the expense of building a dedicated foundation for the solar array. It also elevates the modules, which is often of benefit if there are trees in the vicinity that might shade the array over time.
When installing a system on a client’s roof, we pay attention to the critical details of attaching to the building structure and seal all roof penetrations in accordance with industry best practices. On shingle roofs, this means the use of mechanical roof flashings for each screw that goes through the roof.
Grid-tied solar electric systems utilize PV modules and inverters to deliver clean electricity. These systems first provide electricity to the electrical loads in the home or business. If the system generates more electricity than is being consumed, the excess is delivered to the grid. The utility measures the amount of electricity that the PV system delivers to the grid and provides a credit to the owner’s utility bill. In Maine, we have 12 months to use this excess electricity. Owners are not compensated for any surplus electricity that is generated during the 12-month cycle.
Grid-tied PV systems avoid the need for batteries, which create additional expense and maintenance. The tradeoff with a grid-tied system is that there is no stored energy in the home – at night, on a cloudy day, or during times of high use, electricity is purchased from the grid.
Battery storage can be incorporated with a grid-tied system to provide electricity when there is a power outage or to best utilize time-of-use electricity rates.
It is possible to install a system that offsets all of your electricity consumption through the net metering arrangement described above. Since these systems are modular, a smaller system can be installed based upon your budget or site limitations.
PV arrays may also use a fixed ground-mounted foundation oriented towards south and at an angle that maximizes the systems performance. While this increases cost, it may be preferable in locations where the roof is not an appropriate mounting location.
This approach eliminates any concerns related to the lifespan of the roofing and allows the system to be scaled to the size of the electrical demand. Ground-mounted systems are an ideal solution for community solar projects, which require large scale arrays.
Ground-mounted arrays can also be installed on a pole. This is a common approach for small systems used in grid-tied or off-grid systems. For larger pole-mounted systems, we can utilize a multi-pole mount. Each pole mount requires a concrete foundation that acts as ballast for the array.
For applications where the monthly electrical demand averages 1000 kilowatt-hours, a pole-mounted tracker is a cost-effective solution. Trackers allow the array to follow the sun’s path across the sky to maximize system performance. Because these systems seek to maximize electrical generation in the morning and the afternoon by staying normal to the sun, shading on the horizons should be minimal for optimal performance.
Off-grid PV systems utilize batteries to store electricity when there is sufficient solar radiation to satisfy the electrical demands in the home. The systems, also known as “standalone” systems, range from small systems for running emergency signs and lighting to systems that satisfy the full demands of a home or business. These systems are typically utilized in places where access to the grid is impractical or expensive. These systems are commonly used for seasonal cabins and homes located away from existing electrical infrastructure.
Some off-grid systems are supplemented by a generator that provides consistent power even when there is limited access to the sun. The demand for a generator depends upon the storage capacity of the battery bank, the electricity demand, and the ability for the PV modules to recharge the battery bank.
Due to the need for electrical reliability, the design process for off-grid system is very detailed and requires an accurate assessment of the electrical use at the site.
We provide the design and installation of certain off-grid PV systems and generators. Typically, our off-grid clientele are those who are looking for whole-house systems or larger camp systems. Due to the economics of designing and installing small off-grid systems, it is often difficult for us to attend to the design and installation of systems of one or two solar modules. If you are looking for guidance on a system to satisfy small electrical loads, we are willing to connect you with good resources for doing so successfully.
Sample some of our solar photovoltaic (PV) projects:
We offer system monitoring standard with every system we sell. If you have an Internet connection, our systems can provide remote monitoring that shows how much energy is being produced by the system and will send alerts to us if there are any issues that arise with the system. This provides accountability and quick response to any service issues that might arise.