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?
Module interrow Shading

At the same site but on a different roof… There was ample space on the roof, but the installer placed the modules right up against the parapet wall where it would it would be heavily shaded in the afternoons year round.  Module Shading 2
Module shading 1

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 north so they absorb a bit less direct sun at that angle (reverse of the reason modules are tilted south to take on more sun).
Inverters-on-Roof

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.

This is a reminder that you can not stand on solar PV modules like this if you expect them to last 25 years. Standing on the modules creates micro fractures on the cells that will lead to premature failure. If you were ever in a difficult situation where you needed to step on a module, at least be sure all your weight it applied to the frame and not on the module surface (but even that is risky).

standing-on-modules

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.

This was a NEMA 3R transformer (some of the rain shields are removed in the photo to gain access) and supposed to be rated for outdoor locations and rain, but snow drifts were able to push up and under the shields and into the enclosure where it cause a significant fault. The system outage lasted for months while the insurance companies fought it out.

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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 with multiple existing underground its path. The overhead aerial line was installed at a much lower cost (no trenching, conduit, backfill, or asphalt repair) without disrupting the faculties operations with a road closing.

Overhead Service Drop

The overhead run was constructed from EMT conduits with service heads installed at the top on both sides being supported to (2) 2” RMC support poles fived to the adjacent buildings. The 3 conductors were pulled from the combiner box through the service head and on the other end from the DC disconnect to the service head with 3 feet of additional conductor to create a drip loop. A 66’ piece of aluminum triplex 4/0-4/0-4/0 was fastened to an Arlington 610 porcelain wire holder on each RMC support pole. The overhead conductors were spliced to the THWN feeder conductors using Ilsco PBT-250 insulated splice connections.

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 from either the Municipal Zoning Board, or Planning Board. The first step in obtaining municipal approval is determining which Board your application will need approval from. This is typically done by determining the zoning criteria for the property being developed. If solar projects are a permitted use in the applicable zone than the Planning Board’s approval is required. If solar projects are not a permitted use, than the applicant must obtain the Zoning Board’s approval.

Typically an application is made to either the Planning or Zoning Board which contains the following at a minimum: Application Forms, a fee, Site Plans, Land Survey, Stormwater Report and any other reports. Often, Municipalities will require more than these items, and the level of detail for each will vary from municipality to municipality. For example, Municipality ‘A’ may require an Environmental Impact Report for any land development activity, while Municipality ‘B’ does not. One can usually determine which items will be required from a municipality by looking at the municipality’s site plan application checklist.

Upon submission to the Municipality, the appropriate board will determine whether or not the application is “complete”. A “complete” application means that the appropriate board and its professional’s have received the information (listed in the checklist) necessary to make a decision on the application. Based on the Municipal Land Use Law, a municipality has 45 days to either deem an application complete, or incomplete.

Once deemed complete, the application will be placed on an agenda to be heard publicly in front of either the Zoning or Planning Board. At this public hearing, the applicant is typically represented by a Land Use Attorney, Professional Engineer, and any other professional’s required (Planners, Traffic Experts, etc.) The Zoning/Planning Board typically also has consultants such as an Attorney, Professional Engineer, and Professional Planner which aid them in determining whether an application should be approved/disapproved.

At the hearing the applicant’s attorney will present the application to the Board with the aid of the applicant professionals. The Board will listen to the applicant’s presentation, along with feedback from the Board’s professionals, and the public. The Board will then vote on whether to approve or disapprove the application.

If an application is approved, a Resolution of Approval will be drafted which will usually contain conditions of said approval. This Resolution will become official when it is memorialized at a public hearing 1 month after the original public hearing. The conditions and comments in the Resolution of Approval must be satisfied prior to an application being completely approved through a process called Resolution Compliance. Once the resolution compliance process is complete, the applicant can then apply for building and zoning permits.

Timeline for Municipal Approval – Varies between 4-6+ months

County Approval (21 Counties in NJ)
On a majority of Land Development projects in New Jersey, some form of County approval is necessary. This approval is usually required by the Municipality as a condition of any approval (see above) and a building permit application cannot be made without it. The process for obtaining a county approval varies greatly depending on the County and type of Land Development. Typically, unless a solar project impacts a County Road or County drainage facility, the approval process is fairly administrative in nature. County approval can be obtained independently from a Municipal approval.

Timeline for County Approval – Varies between 1-2 months

Soil Conservation District (SCD) Approval (15 SCD in NJ)
For all land development activities disturbing 5,000 square feet or more, a Soil Conservation District approval is necessary. The SCD is responsible for implementing the NJ Soil Erosion and Sedimentation Control Act which governs certain aspects of land development. The SCD is also responsible for administering the NJPDES Stormwater Phase II Program. As part of this program all land development activities which disturb more than 1 acre, must obtain an authorization of construction general permit (5G3).

Approval by the appropriate Soil Conservation District is typically required as part of a municipalities conditions of approval (see above) and a building permit application cannot submitted without it. SCD approval can be obtained independently from a Municipal approval.

Timeline for SCD Approval – Varies between 1-2 months

Various Approvals Require in the State of NJ
The following is a list of several state programs which may require application and approval depending on the location of the project within NJ:

  • NJDEP Freshwater Wetlands Act
  • NJDEP Flood Hazard Control Act (FHA)
  • NJDEP Coastal Area Facilities Review Act (CAFRA)
  • NJDEP Waterfront Development Act
  • NJDEP Highlands Water Protection and Planning Act
  • New Jersey Meadowlands Commission
  • New Jersey Pinelands Commission
  • Delaware and Raritan Canal Commission

Depending on the location of the project, several or none of the above programs can have jurisdiction on the project. The approval process for each varies greatly based on the location and nature of each project.

Timeline for approval – Varies greatly

Building Permits
A building permit application can be made to 2 different entities depending on the type of solar project. For grid connected projects the New Jersey Department of Community Affairs reviews all applications. For non-grid connected projects, a building permit application can be made the local building department.

As stated above, typically a building permit application cannot be made until the applicant demonstrates Zoning or Planning Board approval.

Timeline for Building Permit approval – 30 to 45 days

Roof Mounted Solar Projects

The approval process for a roof mounted solar project is typically more streamlined than the process for a ground mounted system. The theory behind this is that a building has already received Zoning/Planning approval for construction and the solar panels can be considered an accessory to the buildings existing use.

As such, projects that propose equipment which does not exceed the buildings existing height by an exorbitant amount or extend beyond the existing building footprint typically don’t need Zoning/Planning Board approval. For example, placing concrete inverter pads on the ground adjacent to an existing building will often trigger the need for Zoning/Planning Board approval.

A zoning permit will still be necessary for roof mounted solar projects prior to filing building permit applications, however, the public hearing and formal application process is not necessary.

Building Permits
A building permit application can be made to 2 different entities depending on the type of solar project. For grid connected projects the New Jersey Department of Community Affairs reviews all applications. For non-grid connected projects, a building permit application can be made the local building department.

Timeline for Building Permit approval – 30 to 45 days

Mounting Central Inverters on the Roof

Mounting-Central-Inverters-on-the-RoofMany 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.

If the structural engineer determines the building can handle the load, the next thing to consider is how you will mount the inverter on the roof. One option is to cut out a section of roof membrane and insulation and install a flashed curb that is bolted directly to the roof deck below. Effective, but involves cutting a hole in the roof, which we always try to avoid.

Mounting-Central-Inverters-on-the-Roof-2Pure Power has a better solution that is more cost effective, easier to install, and that doesn’t involve cutting a hole in the roof.

You can place the inverter directly on the roof surface, using an outrigger pad to evenly distribute the weight across the roof membrane and insulation. Polyisocyanurate insulation is has a compressive strength of least 20 PSI, which converts to 2,880 PSF.  A 100kW inverter weighs around 3,000 across a footprint of 15 square feet, which translates to an average load of 200 PSF, less than one tenth the compression strength of the roof insulation.

In the past, we have used 2” thick white outrigger pads (used to distribute the weight of crane outriggers) with a slip sheet which look great! One tip, locate near a wall so you can provide a lateral support to address the concern of tipping over during a hurricane.

Aluminum Conductors

Be careful with Aluminum Conductors

Aluminum-ConductorsThe 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 installed properly, Aluminum can reduce the installed cost and perform just as well as copper.

The four steps and the pitfalls of aluminum will be discussed below

  1. Strip insulation off conductors
  2. Use a wire brush on the bare conductor strands
  3. Apply No-Ox compound
  4. Install a lug appropriate for the thermal cycling

Stripping the insulation – Extreme care must be taken when stripping the insulation from an aluminum conductor.  Using a utility knife may be acceptable for copper, but it is not for aluminum. If the soft aluminum in nicked, over time those strands will break free and the lose strands will cause small shorts and sparks over the air gap of the nick, eventually leading to a failure.

Wire Brushing – You should wire brush the exposed conductor to remove oxidation before applying the oxide inhibitor and terminating the conductor. This step will remove any excessive oxide from copper or aluminum wire and remove any pieces of insulation or other contaminants that might interfere with your connection.

Oxidation – Oxidation is to aluminum what rust is to iron. Oxidation will increase the resistance of the connection. Anti-oxidation compound (AKA “no-ox”) will mitigate oxidation and promote a low impedance connection to the lug.

Thermal Cycling – Due to the thermal cycling from day to night, the conductors expand and contract. Aluminum expands and contracts more than copper and is much softer, so when mechanical lugs are used the cable can work itself loose.  Mechanical lugs should not be retorqued as part of any routine maintenance procedure because repeated tightening of any set crew mechanical lug could result in the eventual biting through of the conductor which will ultimately cause a failure of the connection.  This is why Pure Power Engineering strongly recommends the use of compression lugs, which will ensure a long life and secure connection.

Note: A hydraulic crimper for compression lugs runs about $2,000, but once you have the crimper the material and labor cost is equal for mechanical and compression lugs.