Servicing PV-Equipped HVAC Systems

Photovoltaic (PV) electrical power systems are becoming increasingly common in residential and commercial building applications. The typical PV system encountered by an HVAC technician during a service visit is connected to the building’s electrical system in a manner that’s not directly associated with the HVAC system (or any specific building electrical load). However, as the technology becomes more prevalent, the best HVAC technicians will know how to proceed when they encounter a building or residence equipped with a PV system. 

The alternating-current (AC) connection from a PV system will usually be through a backfed circuit breaker in an existing load center or through a direct connection to the utility service entrance wiring. 

For a typical system, the array of PV modules is usually configured into circuits of 200 to 600 volt direct-current (DC) connected to a large single inverter that converts the PV’s DC energy to AC energy compatible with the utility grid. Photos 1 and 2 show examples of typical PV systems of this type which may be mounted on a roof (possibly out of sight),We are professional wholesale best LED Dome / Reading Lamp Wholesalers,large LED Dome / Reading Lampwholesale order. or on the ground,These are one of the high quality HID Back-Up Light Kit you can buy, with one of the lowest defect rates in the industry. either near the building or some distance away. 

During HVAC service, if there is any question that the PV system is affecting the performance of the HVAC system, opening this disconnect will immediately isolate the PV system and cause it to shut down.You can choose to use the efficient and durable Newest motorcycle H6 Swing all in one hid kit that come in various colors for artistic purposes.This high quality HID Ballast is made in Korea and it has an error message canceller function integrated in the unit. In this condition, all power to the building is provided by the utility grid. Upon re-closing the disconnect, the PV system will resume proper operation (following a code-required five to seven minute start-up delay). 

Today, there is a new and, so far, unique application in which a PV power unit is installed in a direct AC connection to the outdoor unit of the HVAC system. Lennox Industries is pioneering this type of PV/HVAC system in both residential and commercial applications with the Dave Lennox Signature Collection SunSource Solar Ready systems. 

These systems make use of what is known as an AC PV module. To create AC PV, each PV module is provided with a dedicated micro-inverter permanently mounted to the back that produces power at 240 VAC or 208 VAC, depending on the system design. 

The output of the SunSource PV system is wired directly to the outdoor HVAC unit and in most cases will have a visible, well-marked, readily-accessible AC PV disconnect in this circuit.Use our High Quality LED Ceramic Bulb to replace traditional halogen and incandescent spot lights in track lighting. On these units, the PV AC output connection to the outdoor unit is through a small, dedicated circuit breaker panel integrated into the outdoor unit. There is one circuit breaker for the PV circuit output (15 or 20 amps), and a second, larger, circuit breaker (or fuses) protecting the outdoor unit itself. This arrangement allows the system to meet the requirements established by the National Electrical Code. 

As before, when there’s any suspicion that the PV system is affecting HVAC operation (very unlikely), the PV system may be turned off by opening the external disconnect or opening the breaker associated with the PV system in the outdoor unit. Note: always disconnect both sources of power from the HVAC unit before removing access panels and attempting repairs. 

Care must always be observed around any PV system encountered while performing HVAC service. Most PV systems have DC circuits that produce between 200 and 600 volts when energized. These can pose a potential danger any time there’s sunlight on the PV modules. In the case of SunSource HVAC units, only appropriately trained HVAC technicians (such as those who install these systems) should ever conduct repair, modification, or rewiring, of the dedicated PV components associated with them. Even properly trained technicians should not attempt to make changes to the wiring of the HVAC feeder or to the rating or location (in the load center) of the HVAC outdoor unit circuit breaker. These and a few other elements of the HVAC PV system must be retained as installed in order to maintain compliance with the requirements of the National Electrical Code.