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Top 3 Mistakes Developers Let Their Installers Make

We often see the 3 mistakes below being made on many solar projects. These mistakes have an effect on the long term operation, quality, and safety of the system. Perhaps since they don’t have an immediate effect on project closeout, it's not on...

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Nationwide Designs and Plan Sets for Commercial & Utility Scale Solar

With 21 engineers between our NJ, CO, and CA offices, we have unmatched bandwidth to design your solar & energy storage projects fast. What does that mean for your project? Quick turnaround time from quality engineers means you can complete your...

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Urgent: Rapid Shutdown Increases Project Costs Starting Jan 1, 2019

This is a simplified version of my previous article on the new Rapid Shutdown codes taking effect on January 1, 2019. For those interested in the technical details of the code, refer to 2017 NEC 690.12 Rapid Shutdown – Important Changes.

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2017 NEC 690.12 Rapid Shutdown – Important Changes

The 2017 National Electric Code (NEC) dramatically changes the requirements for "Rapid Shutdown of PV Systems on Buildings." Half of the states already adopted NEC 2017 and several more will in the next few months (such as NJ and CT), so you...

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Reduce Costs with Aluminum Conductors on Solar Projects

Its common knowledge that Aluminum (Al) conductors cost less than Copper (Cu). But how big is the difference in price? The answer may shock you.

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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 690.12 Rapid Shutdown for String Inverters on Flat Roofs

The 2014 National Electric Code added a new section of code 690.12 requiring "Rapid Shutdown of PV Systems on Buildings".  Below is the first of 1 of 2 articles we put together to help you understand this code (here is the other: 2014 Rapid...

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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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480 to 208V transformers – Caution when mounting outdoors

480 to 208 Transformers are commonly needed to step down 480V inverters for 208V services. Unfortunately electrical rooms are often crowded with existing equipment. Sometimes there isn’t room for a transformer, so we are often forced to locate...

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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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Photo of the Month - December

Pure Power engineered a rooftop solar PV system with an innovative new method for mounting string inverters. The inverters are mounted on strut stands directly over cable tray, and the AC and DC wiring is all neatly and compactly run in the cable...

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Scary Photo of the Month - November

Im not sure which of these photos is the scariest...

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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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Mounting String Inverters on a Roof

This photo is an excellent example of an inverter installation on the roof. Keeping the inverters next to the array allows the unfused string wires to be kept at a minimum length, increasing safety. Notice how the inverters are tilted to the...

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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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Outdoor Step Down Transformer Fault

When you select the wrong transformer enclosure rating, moisture will get into the transformer enclosure and cause faults. NEMA 3R transformers are effective at keeping out rain, but sometimes no snow drifts.

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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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Overhead conductors instead of underground ductbank

In a recent project we were able to value engineer a DC combiner feeder by running an overhead line rather than trenching an underground duct bank. The feeder would have been a 175 feet underground duct bank routed across a high traffic driveway...

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Photo of the Week - Avoiding Top Entry of Conduits

In this installation, an AC panel board was located at ground level which combined the AC circuits from string inverters on the roof. We wanted to avoid entering the top of the enclosure with conduits, so a trough was used so that the feeders...

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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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Explained: NJ Land-Use Approval Process

Ground Mounted Solar Projects

Municipal Zoning/Planning Approval (566 Municipalities in NJ) All land development activities in the State of New Jersey require some level of Municipal approval. Typically, solar farms require site plan approval...

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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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Mounting Central Inverters on the Roof

Many roofs are designed to support thousands of pounds of HVAC units and large air handlers, so the additional weight of an inverter is feasible in many cases.

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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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Aluminum Conductors

Be careful with Aluminum Conductors

The cost savings of Aluminum conductors is too good to ignore.  Both the engineer and the electrician must respect the differences between copper and the less forgiving aluminum. However, if designed and...

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Using the Full Ampacity You Paid For

When deciding what size and quantity of combiner boxes to use, always remember to use the full capacity of what you are buying.

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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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Reduce Your Combiner Box Expense by 25%

Value Engineering Combiner Boxes

You can save up to 25% on combiner boxes and DC disconnects switches if they are properly designed.  It is well known that you size equipment for 1.56x of the short circuit current.  However, with certain solar...

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Correct DC Disconnect Labels

Over the years, we have seen just about every combination of equations and numbers used to calculate the NEC required values on a DC disconnect switch.  NEC requires these values to be calculated and shown on the DC disconnect switch, but it...

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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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