<img alt="" src="https://secure.redd7liod.com/155840.png" style="display:none;">

Category Archives: commercial-solar

Latest Discussions

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.

Continue Reading

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.

Continue Reading

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...

Continue Reading

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.

Continue Reading

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...

Continue Reading

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...

Continue Reading

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.

Continue Reading

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...

Continue Reading

Scary Photo of the Month - November

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

Continue Reading

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...

Continue Reading

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?

Continue Reading

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...

Continue Reading

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.

Continue Reading

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.

Continue Reading

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...

Continue Reading

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...

Continue Reading

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.

Continue Reading

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.

Continue Reading

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...

Continue Reading

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.

Continue Reading

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...

Continue Reading

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...

Continue Reading