Final Review

The Solar "Dirty Dozen"

Jun 11, 2010 3:13:50 AM

By Saul Inda, Senior Inspector

Currently, California is experiencing a solar "gold rush." Everyone wants and craves solar energy. Contractors from various fields are adding solar PV to their portfolios, and thus, solar training has become abundant. For these reasons, there are new solar contractors all over the state- but a common misconception differentiates between the good and the great. The basics of solar installation can be taught in a week, and with that, many individuals feel as though they are experts. But installing a solar system that will stand the test of time takes an entirely different level of experience. Now we ask ourselves, how can solar installers stand out from the growing competition? The answer lies within this basic principle of virtue: "quality installation."

A properly installed residential PhotoVoltaic system should do two things: (1) produce electricity, and (2) not cause any damage to the structure which it is installed on. Pretty simple, not much to it. Burnham Energy has inspected all types of residential solar electric systems from a wide variety of installers. Although most are installed professionally, one would be surprised as to how many systems fall through the cracks. This ultimately results in costly repairs to the homeowner.

After climbing an infinite number of ladders and walking on hundreds of roofs, I am pleased to present my "dirty dozen" list for residential PV solar systems. The list below will provide assistance in what to look for, and what not to do.

1. Install all equipment following the manufacturer's specifications: Do not mix and match hardware. If you are missing an item, acquire the appropriate part. Do not use whatever is in the truck that seems to make it work. Odds are that a brand X stand-off will work with brand Y rails, but make sure they are listed as compatible before finalizing the installation.

2. Cable management: Properly support all conductors under an array with approved materials. The wires under an array should never come in contact with the roof or any abrasive surface that can cause damage. In time, one will notice that it does not take much to damage the insulation on the conductors.

3. UV damage: the sun's UV radiation can rapidly decay and damage most plastics. Make sure all cable ties, exposed conductors, and junction boxes are UV and outdoor rated.

4. Roof penetrations: A great practice, when possible, is to minimize the amount of penetration to the roofing surface - find alternative routes for cabling and conduit. Remember, less is more.

5. Module and array grounding: This is one of the most important safety issues in a PV installation. Make sure all PV modules and metallic support structures are grounded to an Equipment Grounding Conductor (EGC) with approved grounding lugs or clips. EGCs must be irreversibly connected to main service Grounding Electrode Conductors (GEC) when possible.

6. Electrical boxes and conduit bodies on roof should be accessible: Placing all electrical boxes and conduit bodies under the array makes for a very clean looking installation. However, this is not always a good practice. Access to these items for repairs or service would require temporary removal of solar modules. Generally speaking, it is best that boxes or conduit bodies be adjacent to, rather than under, the PV array. If aesthetics is a factor, simply mounting these devices at or near the top of the solar array will provide adequate access and conceal these devices from viewers below.

7. Raceways (conduit) on rooftops: Support all conduit spans every 3 to 4 feet and within 12 inches of any coupling or fittings. Avoid penetrating any roof surface when possible.

8. Flashing installation on roof: Any attachments to roof must be properly sealed to prevent leakage. Use the recommended sealing method for the existing roof type. Urethane caulks such as Sikaflex 1a are both temperature and UC resistant. Silicones and roofing tars are less durable.

9. Expose array conductors: Don't do it! Protect all conductors in conduit or secure them under or close to the solar array. Also, make sure exposed conductors are USE-2 90C rated or listed as "PV wire."

10. Overcurrent protection: Make sure all over current protection devices are consistent with PV system voltages. Check that all fuses in combiners, switches, and inverters are DC rated (DC side of system.) Check if breakers are properly sized to PV system (AC side.)

11. Solar warning signage: All solar warning signage should be durable enough to survive the outdoors. Install warning or identification labels on conduit carrying DC voltage, AC & DC disconnect switches, main electrical services, and any other locations that would warn of a secondary source of power. This is primarily for the safety of all those that may come in contact or work with the main electrical service.

12. Check for damage on the roof: After completing an installation, the last thing you want is a leaky roof. Take care while walking on the roof and survey the area for damage. The last guys on the roof are usually the first to get blamed if there is a leak!

Ultimately, what is conveyed above is the importance of a quality installation. In order for everyone to take part in and benefit from this technology, it is crucial that simple measures be taken in order to perfect a PV solar installation. If the installer produces a quality product, then a chain of happy homeowners will continue to unravel. It is these small details that make a big difference in the long-term of the PV system and the homeowner's appreciation with the product they invested. This new era of solar installations has the ability to bring great positive change to current lifestyles. Let us continue to be assets to the community by creating a product that undeniably supersedes others by following the basic principle of quality.

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