The appropriate building permits will have to be obtained and the system will need to pass an inspection. This can be a painful process if you are not used to performing electrical work. Inspectors will be on the lookout for all possible NEC violations, including sloppy work, improperly sized conductors, lack of conductor protection, and improper equipment grounding and labeling (see “Residential PV Systems: Common Code Violations” in HP141). If your system doesn’t pass muster, you will usually be charged a reinspection fee each time the inspector comes out. Professional installers who have been in business for awhile have been through many inspections and have a good handle on what the local AHJ expects. They have the experience and the knowledge to work with inspectors if anything comes up that the inspector may not be familiar with. Homeowners will typically be greeted with a greater level of scrutiny from building inspectors. Additionally, there is a new section in the 2011 NEC, section 690.4(E) stating that PV equipment and systems, and all associated wiring and interconnections, shall be installed only by “qualified persons.” See Code Corner in this issue for a discussion about what constitutes a “qualified person” in the eyes of the NEC and your local AHJ.
Installation labor costs typically account for 10% to 20% of a system’s total cost. Labor costs for a simple 3 kW roof-mounted, batteryless grid-tied PV system might be between $2,000 and $3,500. The exact amount you could save by installing the system yourself will depend on your particular system type, and its size and mounting method. For example, battery-based PV systems are much more complex and require more time to install the extra components (such as the battery box, batteries, battery cabling, charge controllers, battery metering, extra disconnects, and overcurrent protection). Array size will dictate how many module mounts and inverters are required. This, in turn, will determine the time required to install the complete system. The array mounting method will be a major factor. For example, a ground-mounted system (see “PV Ground-Mounting” in HP144) requires much more prep work—such as digging footers and conduit trenches, setting posts, and pouring concrete—compared to a roof mount.
A DIY system may impact your incentive eligibility. While you can still take the 30% federal tax credit, in some cases, you may not qualify for state, local, or utility rebates if you install the system yourself. A self-installer could lose out on thousands of dollars in state and/or utility incentives.
To find out what your system will qualify for, research the requirements for the various PV incentive programs in your area (see the Database of State Incentives for Renewables and Efficiency at www.dsireusa.org). For example, Xcel Energy’s Colorado customers who install their own systems are eligible for the Xcel Energy Solar Rewards program, which currently offers a $1.75 per watt payment (and $0.04 per kWh production incentive) for systems under 10 kW. However, these systems are not eligible for the state rebate program (currently set at $1.50/watt) unless they are installed by a contractor listed in the rebate program database. In Oregon, to obtain Oregon’s Energy Trust rebate, PV systems must be installed by a qualified Energy Trust solar trade ally contractor. Self-installed systems do not qualify. Any money you may be expecting to save by installing your system will be offset if you can’t capture all of the available incentives.
When you approach any new activity that’s potentially dangerous, it goes without saying that you should proceed slowly, methodically, and with extreme caution. When it comes to PV safety, you need to consider both design safety and installation safety.
During the design, many critical safety aspects must be considered. For example, array fastening systems and hardware must ensure a secure rack-to-roof attachment. Nothing will bring your efforts to a crashing halt like modules being torn off the roof during a heavy wind storm. System wiring and overcurrent protection devices must be appropriately specified to prevent fire hazards. Conduit size, the number of conductors running in a conduit, and the installation method should always meet NEC requirements. Appropriate ground-fault protection is a requirement for PV systems mounted on dwellings and for some pole- and ground-mounted systems as well. Batteries introduce additional safety considerations, since huge amounts of stored energy are present. They also require dealing with sulphuric acid, ventilating flammable hydrogen gas to avoid buildup, and taking precautions to avoid short-circuiting the batteries during installation or future maintenance.
Once the PV installation begins, a whole new set of safety requirements must be considered. (See www.osha.gov/dep/greenjobs/solar.html for an overview of installation hazards and precautions.) Most modern PV systems operate at dangerously high DC voltages and electrical shock hazards are present during installation. There are many precautions that must be taken to ensure you do not come into contact with these high voltages, like understanding and following safe installation order procedures. For instance, disconnect and inverter wiring should always be attached before the PV array circuits or grid are connected. Have a well thought-out plan for wire management and be on the lookout for array wiring that inadvertently gets pinched between the modules and the mounting structure. This can damage the insulation and potentially lead to ground-faults and arcing once the system is connected.
Never underestimate the importance of suitable personal protective equipment—cutting corners here could have life-long impacts for you and your family. Basic safety equipment like eye protection, ear protection, and respiratory protection should be used when needed. High-voltage electrician’s gloves and glove protectors should always be worn when working on live high-voltage DC circuits. Installing a roof-mounted system poses potentially lethal fall hazards. While many homeowners may be comfortable working on the roof unprotected, that doesn’t mean that it’s sensible. Fall-protection equipment, including harnesses, safety lines, and proper anchoring systems, should be used. Even if you’re installing your system at ground level, ground-mounted systems often necessitate working with power augers and trenchers, which both pose operation hazards.