How Solar Works

Photovoltaic cells (Photo = Light, Voltaic = Electricity), or solar cells, produce electricity from sunlight. When sunlight shines on a solar cell, some of the light is absorbed, knocking lose electrons. The solar cell funnels these loose electrons through wiring creating DC (Direct Current) energy. DC Power is the same power source stored in batteries or produced by a cars alternator. Panels are measure in watts per hour. So a 240-watt panel produces 240 watts of energy per hour (could run four 60 watt light bulbs for an hour).

Inverters convert the DC power produced from solar panels to AC (Alternating Current) power our homes and businesses use. The two main classes of inverters are central or string inverters, and micro inverters. 1. Central inverters, connect multiple panels, into strings (i.e. 12 panels per string), and one or multiple strings per inverter. So for example, a solar system made up of 36 panels, might have 3 strings of 12 panels each on one central inverter. The benefit of central inverters is ease of maintenance, higher efficiency, and often lowering costs. 2. Micro inverters are install one per panel. So if you have 36 panels, you would have 36 micro inverters. The benefits of micro inverters is they work better with shaded or multiple angled roofs, provide integrated performance monitoring, and are often easier to wire to the sub-panel or meter main.

The Racking and Mounting systems are what the panels are mounted to. Usually racking components are made from aluminum and stainless steel, but some panels can use the roof itself for racking. Racking is the foundation of the system and when it is done correctly will last the life of the system and provide an aesthetically pleasing look. System racking usually comes in two flavors, roof mounted or ground mounted.

Roof Mount systems usually have a lower cost then ground mounts, and do not require extra real estate, which can often is unavailable. They usually have a footing to connect to the roof, flashings to prevent leaks, “L” feet that are used to connect the footing to the rail, rails that the panel sit on, clips to connect the panels to the rails, and finally grounding equipment for safety and to help prevent electrical damage.

Ground Mount systems offer several advantages if the space is available. Often roofs do not have enough space, are not oriented properly, have unfavorable slopes, or may not be aesthetically pleasing. In these situations a ground mount system can be designed for maximum solar production. Ground mount systems have most of the same components as roof mount system. In addition they require holes to be dug, and concrete to be poured to support steel footings, caps to allow for horizontal supports, and cross bracing for strength and seismic stability.

Performance monitoring allows a solar customer to evaluate how their system is performing. It can take on all shapes and sizes, from reading the display of the inverter to an integrated approach using networks and the Internet. For purposes of this discussion we will discuss performance monitoring using a computer.

Some performance monitoring systems like the SMA Sunny Web Box, monitor the inverter(s), and allow a customer to view their production at their local computer, or with Sunny Portal, anywhere in the world via the internet. It can be setup to send you an email of daily production, or notify your vendor if a problem is detected. Other systems like Eco Dog's Fido Advisor, allow you to monitor not only the production of your solar system, but also the electrical usage by circuit within your house. You can see how much energy the hot tub, your refrigerator, guest room or rental unit are using, and how much the solar system is producing. Many companies offer remote performance monitoring today. These companies will monitor a system remotely, notifying vendors and homeowners when problems occur with their system. These companies charge a reasonable fee for this service. For larger commercial systems this is a requirement to participate in the state rebate program. As part of our solar analysis, Synergy will select the best option to fit the customers needs.

A solar system needs to be sized and integrated into the utility. The meter, provided by the utility, keeps track of the production of the solar system and the electrical usage of the household. Often this can be the logical place to connect the solar system. However, any electrical panel connected to the meter, can be used, as long as it is sized correctly. This sizing is usually done when we do our solar evaluation. Ensuring the correct sizing is done by Synergy as part of the solar analysis.