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Category Archives: energy-storage

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2014 NEC 690.12 Rapid Shutdown - More on Conductor Length

Our first article 2014 NEC 690.12 Rapid Shutdown for String Inverters on Flat Roofs we explained the basics of implementing a rapid shutdown system using string inverters on a roof.  In that article, we gave a simple example of a single array.

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2014 NEC 705.12(D)(2) - A new 120% rule... and more

In a previous article “The 120% Rule Explained – 2011 NEC 705.12(D)(2)” we clarified the philosophy of the 120% rule for load (supply) side interconnections of solar PV systems. The 2011 code was clean, understandable, and easy to safely apply.

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Photo of the Month - January

Here is something that’s crazy, and yet we completely understand why they did it. Some evil genius put duct tape around the vents of a NEMA 3R transformer. If this transformer is heavily loaded it runs the risk of overheating, but at least snow...

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The 120% Rule Explained – 2011 NEC 705.12(D)(2)

Everyone knows about the 120% rule, but not everyone understands the situation it is trying to protect against. This article will explain Pure Power’s philosophy on the 120% rule.

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2 Important settings for Thermal (IR) Cameras

Thermal (IR) cameras are a great tool for preventative maintenance and inspection of your PV system. With a little thermography “know-how” and some image focusing, problems can be discovered quickly before they create a fault or safety hazard in...

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Scary Photo of the Month - September

On this system, the installer stacked ballast so high that it shades the modules at noon of each day. Why would anyone use a hollow block for ballast?

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Scary Photo of the Month - August

We were called out to investigate a performance issue at a site, and were shocked to see this wire management. We suspect the AHJ made this contractor install physical protection after the strings were installed, which is why the contractor cut...

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Scary Photo of the Month - July

Just when I thought I have seen it all... Notice the mid-clamp that was never attached because the module was raised off the rail. Scary!

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Scary Photo of the Month - May

I appreciate Shoal's new arc fault technology as shown in this advertisement, however I was shocked to see the photo of a man standing on PV modules.

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Scary Photo of the Week - Inverter Repair Gone Wrong

While conducting O&M on a Satcon 250kW central inverter, we noticed this fan with an object lodged between the blades.

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Mysterious water in combiner boxes

During O&M we often find combiner boxes and disconnect switches with water inside them, despite the box being NEMA 4 and fully gasketed, no top or side penetrations, and weather tight connectors properly installed.

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How NOT to clean PV modules

Here is a video I found on the internet, produced by American Apparel. I figured I would share it as an example how NOT to clean PV panels.

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Photo of the Week - Wire Management

At this site, the intermodule wiring is zip-tied to the rails but the string homeruns are laying loose on the roof, which is poor workmanship. Over time the rough shingles will wear away on the insulation compromising its integrity and putting...

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Photo of the Week: Keep drains clean

A roof drain clogged causing the water to rise in the surrounding area. This installation has poor wire management, as shown by a connector sitting loose on a ballast block. Once the water rose and got in the connector, it began to short out...

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Photo of the Week: Keep the site clean

On our first operation and maintenance trip to this site, we discovered an old broken module stashed under a HVAC unit. This module was not secured, and would surely have become airborne during a hurricane or tropical storm. This module could...

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Photo of the Week: Maintain Vegetation

Two things went wrong here. First, the vegetation was not maintained, allowing it to grow tall enough to shade the modules and cover the modules in lots of pollen. The second mistake is improper seeding. If the site has proper low-growing ground...

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Photo of the Week: Improper Raceway

This installer gets full points for creativity, but fails miserably for inappropriate construction means and methods. These cables are not protected from physical damage, and they are not outdoor rated so the UV rays will deteriorate the cables...

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Photo of the Week: Corrosion

NEMA 3R and 4 inverters and outdoor cabinets may be rated for outdoor use, but any scratches in the paint will expose the metal to rusting. Once the rust gets a foothold, it will quickly spread. In this case, the corrosion should be sanded,...

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Photo of the Week: PVC Conduits

PVC conduits are acceptable when used properly (lots of expansion joints). Metallic conduits (EMC, IMC, RGS) are more expensive, but should be in areas subject to physical contact with other items (such as riser up walls, in electrical rooms,...

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Now is the Time of Year For Solar Maintenance

Solar arrays are valuable revenue generating assets that require a certain amount of maintenance.  How much exactly depends on what type of installation we are talking about (ground mount vs. roof mount), the size of the installation (obviously...

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