Solar System Components

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.

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Some of the companies whose products we install.

PV Module Kyocera Solar Module
PV Module Kyocera Solar Module

 

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.

PV modules are rated in watts, based on the maximum power they can produce under ideal sun and temperature conditions. You can use the rated output (along with a figure representing your local solar resource and an efficiency factor) to determine how many modules it will take to meet your electrical needs. Multiple modules combined together are called an “array.” Although framed modules are most common, PV technology also has been integrated into roofing shingles and tiles, or peel-and-stick laminates for standing-seam metal roofs.PV modules are very durable and long- lasting – most carry 25-year warranties. They can withstand severe weather, including extreme heat, cold, and hail.
Array Mounting System Quick Mount PV Flashings
Array Mounting System Quick Mount PV Flashings

 

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.

Typically, arrays in urban or suburban areas are mounted on a south-facing roof, parallel to the roof’s slope. In areas with a lot of space, or if your roof isn’t ideal because of orientation or shading, pole- or ground-mounted arrays are available. Pole-mounted PV arrays can incorporate tracking, automatically following the sun across the sky from east to west each day. Tracked PV arrays can increase the system’s daily energy output by 25% to 40%, but they come with more cost, complexity, maintenance, and potential failure than fixed arrays.
Midnite Solar Combiner Box
Midnite Solar Combiner Box

 

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 output of each breaker/fuse is connected together on a common bus bar to which a positive output wire is connected. The strings’ negative wires are simply connected to a common bus bar along with the negative output wire. Some battery-less grid-tied inverters integrate a combiner box on the input side of the inverter, eliminating a separate combiner box. And some grid-tied systems only have a few PV module strings (3 or less), and don’t require a combiner box.
DC Disconnect Square D
DC Disconnect Square D

 

DC DISCONNECT

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.

Solar Charge Controller Outback MPPT
Solar Charge Controller Outback MPPT

 

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.

To maximize their life, avoid overcharging or undercharging them. Most modern charge controllers incorporate maximum power point tracking (MPPT); this optimizes the PV array’s output, to maximize energy production. Some battery-based charge controllers also include a low-voltage disconnect for the DC loads, to help prevent over-discharging that can permanently damage the battery bank.
Battery-Bank-Surrette
Surrette Battery Bank household

 

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.

Although similar to car batteries, the deep cycle batteries used in solar-electric systems are specialized for the type of charging and discharging they’ll need to endure. Flooded lead-acid batteries are most commonly used in solar-electric systems and are the least expensive, but they require adding distilled water occasionally to replenish water lost during the charging process. Sealed batteries, absorbed glass mat (AGM), and gel-cell, do not require adding water and are often used for grid-tied systems where the battery bank is usually small, and the batteries are typically kept at a full state of charge.
System-Meter-Fronius
System Meter Fronius

 

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-DC-to-AC-converter-Fronius-150x150
Inverter (DC to AC converter) Fronius

 

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.

Most grid-tied inverters are designed to operate without batteries, either tying to one or more strings (series grouping) of modules, or using a “microinverter” for each module. Microinverters offer module-level monitoring and maximize array output with module-level MPPT, enabling each module to operate independently of the others.Battery-based inverters for off-grid or grid-tied use often include a battery charger, which is capable of charging a battery bank from either the grid or a backup generator during cloudy weather. Most battery-less inverters can be installed outdoors, but most battery-based inverters aren’t weatherproof and should be mounted indoors, close to the battery bank.
Inverter-AC-disconnect-Square-D
Inverter AC Disconnect Square D

 

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-Monotoring-SMA

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
AC Breaker Panel

 

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.

Just like other electrical circuits, an inverter’s electrical output needs to be routed through an AC circuit breaker. This breaker is usually mounted inside the building’s main panel, which enables the inverter to be turned off and isolated if servicing is necessary. The breaker also safeguards the circuit’s electrical wiring.

Kilowatt-Hour-Meter-Utility-Meter-Centerpoint-Smartmeter

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.

Backup-Generator-Honda
Backup Generator

 

BACKUP GENERATOR

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.

Engine generators can be fueled with biodiesel, petroleum diesel, gasoline, or propane. These generators produce AC electricity that a battery charger (either stand-alone or incorporated into an inverter) converts to direct current, which is stored in batteries. Like most internal combustion engines, generators tend to be loud and polluting, and do require maintenance. A well-designed PV system will require a running generator only 50 to 200 hours a year.
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