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There are typically three factors that should be addressed when considering which type of solar installation is best for your needs, 1) mounting style and location, 2) interconnection type (how the electricity is going to be used) and, 3) solar technology. Both the cost and the overall reliability of the system can be significantly affected by any combination of these choices.
The first thing to consider is the location and style of the solar array. Are you going to be positioning the solar array on the rooftop of your structure, or will the array be ground-mounted somewhere on your property? Will the system be ballasted or require penetrations? Your installer should perform a site evaluation prior to presenting you with any job quotes. During the evaluation the installer will assess the structural integrity of the location, the possible shading conflicts and the amount of available space. Based in part on this information, the installer will make a recommendation for the location and style of the array that best meets your needs.
The most common type of solar array installation is the rooftop mount. The structure's load capacity, the location of HVAC units and vents, and nearby objects that could cause shading issues must all be considered when assessing a rooftop location.
Ground-mounted solar arrays are customarily used in large (<100kW) installations where an expanse of land clear of vegetation is readily available. These installations can be easier to install, aesthetically pleasing and allow for better maintenance access. However, they may need to be cleaned more often.
Although rooftop and ground-mounted installations are the primary installation types, many people have worked with their installers to come up with mounting solutions that suit their specific needs. For example, solar modules make excellent awnings and can be seamlessly integrated into covered parking structures.
Most commercial property owners prefer the ballasted solar array. The low-profile array is fixed in place by either it's own weight (self-ballasted), small cement blocks, or some combination of the two. Eliminating the need for penetrations in the structure helps to safeguard against possible leaks. However, some rooftops may not be engineered to handle the additional weight.
Where the added weight of a ballasted solar array is a concern, building owners can choose to have the system mounted directly to the structures framework. Penetrations made in the rooftop are sealed against moisture using traditional roofing methods. This style of mounting is clean, secure and lightweight. However, the added time needed for installation will likely be reflected in the labor costs.
Trackers are an exciting development in the world of solar. Tracking units allow the modules to follow the path of the sun throughout the day, increasing system energy production by approximately 20%. Due to the higher cost of installation and necessary preventative maintenance, we currently only recommend this technology on large (>100kW) installations.
The decision about whether to build a grid-tied (connected to utility), off-grid (no connection to utility), or hybrid connected (grid-tied with battery back-up) solar array has a considerable impact on the design and cost of your system. You should be prepared to discuss your energy needs with your installer prior to the performance of your site evaluation. The location and the size of the array will need to be adjusted based off of the type of interconnection you choose.
Grid-tied solar systems are the most common type of installation. In this case, energy from the solar array is converted from DC power to AC power by the inverter and then fed into the building's electrical service. The power generated by the array is used first by the building, any excess power is fed into the Utility's grid and credited to the owner's account for future use. Grid-tied installations are the least expensive to install and simplest to maintain.
Those who are serious about declaring their energy independence, or are simply too far from a utility grid should consider installing an off-grid system. Energy produced by the array is stored in a series of batteries. The building's load is then serviced from the batteries. This installation type is considerably more costly and requires more preventive maintenance than grid-tied, but can be the best solution for some.
A hybrid-connected system is perfect for those who get their power from the grid, but require protection from periodic blackouts. The energy from the solar array will provide power to the building similar to a grid-tied system, but will also work to keep a series of batteries charge that can back up your emergency power needs. This type of system is generally employed at remote locations and hospitals.
The two most common types of solar technology are silicon cell based and thin film based panels. Silicon cell based panels, more commonly referred to as flat-plate modules, are the most widely used type of solar technology. Thin film is an exciting technology that has allowed manufacturers to create solar modules without the added cost of silicon.
Flat-plate modules produce the most energy while utilizing the least amount of space. The modules come in a variety of sizes and are now available in sleek all-black designs.
This thrilling technology is still in its infancy. Currently, thin film modules require significantly more space to generate the same amount of energy as a standard flat-plate module. However, these modules can be integrated beautifully into some standing seam rooftops without any penetrations and can be a cost-effective option for those with plenty of space to spare.
