Building Permit for Solar Panel Installations

This permitting process may take just a few days to a couple of months depending where the project will be so it’s important to choose an experienced PV design company to help you along the way.

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Do I need a permit to install solar?

 

Converting solar radiation to usable electric power requires careful design and permitting. Your solar project will involve the attachment of heavy equipment to your roof and the introduction of additional current into your home’s electric distribution system.

Not surprisingly, most jurisdictions require the submittal of a solar permit before construction is allowed to begin. This permitting process may take just a few days to a couple of months depending where the project will be so it’s important to choose an experienced PV design company to help you along the way.

At Avila Solar, we offer expert and timely solar PV pre-design support, single-line diagrams, and complete permit service for business across the USA.  Get your free consultation today.

Planning for Success

 
Our job is to design safe, efficient solar systems that are compliant with all applicable building, fire, and NEC electric codes, as well as we will meet your utility’s interconnection requirements. We create plan sets that specify exactly how the solar panels are attached to the roof.
 
If required by the jurisdiction (it almost always is), our plans are approved by structural engineers to verify the roof can handle the additional weight of the system, even when covered with snow or buffeted by high winds. Our plan sets specify the details that the electrician will need to connect your system to your existing electrical wiring.
 

We ensure that the building’s existing circuits can handle the additional current produced by the system and that the system can be de-energized quickly in the event that emergency responders need to fight a fire at your home or business. From your utility’s perspective, if you intend to connect your solar system to their electric grid, they will want to know that the system is built to established standards and that it won’t cause problems as it’s operating with their grid infrastructure.

A good design results in a safe solar system, operating at maximum efficiency, that will be awarded a building permit quickly, will be assembled by the installers without confusion and will be allowed to operate in parallel with the electric utility.

Using Solar PV Design Tools

Solar designs are usually created with computer drafting programs such as AutoCAD. These programs were created for a wide variety of applications, not just solar design. Therefore, it is extremely helpful to use a CAD drafting tool that was created specifically with solar design in mind.

The right tool can save hours of tedious drafting work. We’ve developed our own AutoCAD Solar Design Tool to automate some of the time-intensive processes associated with solar planset drafting, and it’s available for a free trial on our website.

There is no right or wrong way to create a solar planset. As long as the planset gets permitted and gives clear instructions to the install team, then it has served its purpose.

Here is one possible way to create a solar permit.

 

The Planset

The drawing sheets that make up a typical solar plan.

PV-1

The first page should include an outline of the scope of work for the project, including the quantity and type of equipment that’s going to be used. It should also include general notes detailing any specific requirements for a given project, such as the National Electric Code and Building Code that apply.

These codes are updated periodically but are not adopted uniformly by all jurisdictions. The system must be designed to the specific requirements of the code in use by its jurisdiction

PV-2

This page is commonly referred to as a “site plan”. It should show the aerial representation of the home or business, plus the location of the new solar equipment to be installed.

PV-3

This page can be called the “layout detail” or “mechanical” page. It should show each solar array, with information about how the racking and roof attachments are designed. It also contains a table of project information. This information includes roof type, attachment type, structural information, and attachment spacing.

PV-4

This page shows the line diagram, conduit schedule, and other electrical information. Depending on the project, the wiring of the system might be represented as a “Single Line Diagram”, or a more detailed “Three Line Diagram”. The line diagram will show each piece of equipment, and how it’s wired into the rest of the system.

one line electrical drawing

The “Conduit Schedule” is a table that shows the size and quantity of the various wires in the system. The size of the wire, ground design, conduit runs, and size of any OCPDs are detailed in this sheet.

PV-5

This is the signage page. Depending on the local requirements and the NEC code year that applies, there will be different sets of labels required for the electrical equipment. Some projects may also require a site placard, a simplified version of the site plan in PV-2.

Once the design is complete, approved by structural or electrical engineers if required, it can be submitted to the jurisdiction for permitting and to the utility for interconnection approval.

It’s important to note that a good designer isn’t finished when the plan set is done. He or she will be your partner through the permitting, interconnection and construction process to ensure the system is approved as designed so that it operates safely and at maximum efficiency for many years of sunny days!

Important Terms

 

PV: Photovoltaic. 

The photovoltaic effect describes the process in which sunlight is transformed into electricity using carefully produced semiconductor material.

OCPD: Overcurrent protective device. 

The electrical equipment that will prevent the wiring or machinery from receiving more current than it can safely handle. One application is the circuit breaker that prevents the solar system from feeding too much power back into the electric grid.

Interconnection: 

This word refers to the way you connect a PV system to the existing electrical system of the home or business.

Breaker in main:

One of the most common types of interconnection. It’s exactly what it sounds like: installing a new solar breaker in the existing main panel. In practice, this breaker looks like many other loads in your main service panel.

120% rule:

This is an equation used to determine the max allowable OCPD size allowed for breaker in main interconnection.

Max OCPD = ((Main panel busbar rating • 1.2) – (Main breaker rating))
For example, if the main panel has a 200A bus and a 200A main breaker, the max allowable backfeed is 40 amps.
Calculation: ((200 • 1.2) – (200)) = 40A

Lineside tap: 

Also known as a “supply-side tap”. The installer connects the solar system to the service entrance conductors upstream of the main breaker. Rather than using a circuit breaker in the main panel as your OCPD, this interconnection uses a fused AC disconnect.

AC Disconnect:

The AC disconnect is used to separate the inverter from the electrical grid. It is usually a switch installed outside, near the meter so it can be used to de-energize the system for maintenance, or in the event of an emergency.

Solar Equipment

 

Modules

Commonly referred to as solar panels, modules are a packaged collection of solar cells, usually encased in metal and glass. Modules vary in output power or “wattage”.

Inverters

Solar modules produce DC electricity, while most homes and businesses use AC electricity. An inverter is a piece of equipment that converts DC to AC. There are a few types of inverters, outlined below.

String inverters: 

These are the oldest and least expensive kind of inverters. Modules will be wired into strings, which must have the same voltage and amperage throughout the string. In order to achieve consistent voltage and amperage throughout a string, the modules must be arranged with the same pitch and azimuth and shading as the others. If one module in a string has lower voltage (due to shade, for an example) then the rest of the modules in that string will operate at the level of the lowest-performing module.

Micro-inverters:

While string inverters can accommodate several modules, with micro-inverters each module will have its own inverter, right underneath the module. Micro-inverters perform better in shady conditions because each module can operate independently of the others.

This also means that modules with different pitches or azimuths can be wired together in a “branch” without causing any performance issues. Additionally, the failure of a single inverter will not de-energize the entire solar system

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Building Permit for Solar Panel Installations

This permitting process may take just a few days to a couple of months depending where the project will be so it’s important to choose an experienced PV design company to help you along the way.

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