To achieve the optimal system, it has to be designed specifically for your home or business. Texas Solar Outfitters offers the widest range of solar system components, and design options. If a ‘solar’ company offers one panel and one inverter choice – they’re selling, not designing – don’t buy it. Here are some of the most common components found in solar-electric systems.
Some of the companies whose products we install.
PV MODULES (or solar-electric modules)
PV modules are the most obvious of all solar system components. They are considered a solar-electric system’s defining component. Inside, semiconductor materials use light (photons) to move electrons in a circuit – what’s known as the “photovoltaic” effect.
ARRAY MOUNTING SYSTEM (or mounts, racks)
Mounts provide a secure platform for anchoring your PV modules, which keeps them in place and oriented correctly. Modules are generally mounted on a rooftop, atop a steel pole set in concrete, or at ground level. The specifics of your mounting system will vary considerably, depending on which method you select.
COMBINER BOX (or series string combiner)
The array combiner box is used to wire and combine parallel strings of PV modules. These are most commonly found in off-grid systems, although larger on-grid systems will have combiner boxes as well. Coming into the input side of a combiner box will be the positive and negative wire for individual module strings, each with its own terminal. Each positive terminal is internally connected to a series circuit breaker (or fuse) for that string.
The DC disconnect is used to safely interrupt the flow of electricity from the PV array. It’s an essential component when system maintenance or troubleshooting is required, and may be mandated by local inspectors. The disconnect enclosure (sometimes a part of the inverter package) houses an electrical switch rated for use in DC circuits. It also may integrate either circuit breakers or fuses, if needed.
CHARGE CONTROLLER (or controller, regulator)
A charge controller’s primary function is to protect the battery bank from over-charging. As a battery becomes charged, the controller moderates the flow of electricity from the PV modules. Batteries are expensive and need careful treatment.
BATTERY BANK (or storage battery)
PV modules produce electricity only when the sun shines on them. If your system is designed to provide energy without the utility grid, you’ll need a battery bank – a group of batteries wired together – to store energy so you can have electricity at night or on cloudy days. For off-grid systems, battery banks are typically sized to keep electricity running for up to three cloudy days. Grid-tied systems also can include battery banks, which provide emergency backup power during grid outages, to keep critical electric loads operating until grid power is restored.
SYSTEM METER (or battery monitor, amp-hour meter)
System meters measure and display several different aspects of a PV system’s performance and status – tracking how full your battery bank is; how much electricity your solar-electric array is producing or has produced; and how much electricity is being used. Web-based monitoring is offered in some metering packages; this is extremely handy to keep tabs and potentially troubleshoot the system. Operating your solar-electric system without metering is like running your car without any gauges – although it’s possible to do, it’s always better to know how much fuel is in the tank.
INVERTER (or DC-to-AC converter)
Inverters transform the DC electricity produced by the PV modules or from batteries into the alternating current (AC) electricity commonly used for lights, pumps, and other electrical appliances. Grid-tied inverters synchronize the electricity they produce with the grid’s AC electricity, allowing the system to feed any unused solar-made electricity to the utility grid.
INVERTER AC DISCONNECT
Utilities usually require an AC disconnect between the inverter and the grid. Some grid-tied inverters have integrated AC disconnects, but these may or may not meet local requirements, calling for a separate PV system AC disconnect box, usually located near the utility kWh meter. In battery-based systems, an AC disconnect is also the AC breaker panel and any other AC power source. It is usually incorporated into an inverter bypass breaker assembly, allowing the AC loads to be fed by the inverter or by another AC power source, such as a backup generator (if power from the inverter is unavailable).
PV PRODUCTION MONITORING
An additional meter to measure solar production is useful for tracking system performance, and is needed for production-based (per kWh) incentives. This can be a dedicated kWh meter that counts the kWh coming out of the inverter, or can be a full revenue-grade or Web-based data-monitoring package.
AC BREAKER PANEL (or main panel, AC load center, breaker box, fuse box)
The AC breaker panel is where a building’s electrical wiring connects to the source of the electricity, whether that’s the grid or a solar-electric system. This wall-mounted panel or box is usually installed in a utility room, garage, or on the building’s exterior. It contains a number of labeled circuit breakers that route electricity to the various rooms or household circuits. These breakers allow electricity to be disconnected for servicing, and they also protect the building’s wiring against overcurrent, which may cause electrical fires.
KILOWATT-HOUR (kWh) METER (or utility meter)
Most homes with a grid-tied solar-electric system will have AC electricity coming from and going to the grid. A bidirectional kWh meter can cumulatively track the flow in both directions. The utility company often provides these special meters at no cost.
Off-grid PV systems can be sized to provide electricity during cloudy periods. But sizing a system to cover a worst-case scenario, like several cloudy weeks during the winter, can result in a very large, expensive system that will rarely be used to its capacity. To spare your pocketbook, size the system moderately, but include a backup generator to get through those occasional sunless stretches. Generators are also used to provide battery – equalizing charging – occasional, high-voltage, prolonged charging that brings the weaker battery cells up to the charge level of the stronger cells.