aurora Basics

AURORA BASICS

Design

To design a good layout, we need to be equipped with tools and methods that allow for accuracy and best practices for installation. This training will cover the basics with some hands on activities to practice.

1 | INTRODUCTION TO PV ARRAY DESIGN

THE BASICS:

The main items to keep in mind for production are:

Azimuth
Shade
Obstructions
TSRF

Be sure to also keep in mind:

We are responsible for creating a quality design for the customer
We are responsible for designing a quality installation for the install crew

THE BASICS:

The main items to keep in mind for production are:

Azimuth
Shade
Obstructions
TSRF

Be sure to also keep in mind:

We are responsible for creating a quality design for the customer
We are responsible for designing a quality installation for the install crew

AZIMUTH

Azimuth is the direction that the roof mounting plane is facing in precise degrees.

A pitched roof with an azimuth of 180° (South) will have the best overall production. Put most mods here.
Azimuths of 90° (East) and 270° (West) are the next preferred roofs after South.
An Azimuth of 360°/0° (North) is the least preferred orientation. Avoid putting mods here

SHADE

Another factor to consider when designing your layout is shading.

Choose roofs with less tree shading or shade from nearby structures.
This can have a dramatic effect at times. It can even cause a south facing roof to be less preferential for production than a west or east facing roof.

OBSTRUCTIONS

When designing a layout, it is important to consider the placement of roof obstructions:

Obstructions can limit the array area on the roof mounting plane.

Obstructions can cast their own shading.
Be sure to thoroughly review roof photos to avoid missing any obstructions not visible in the aerial imagery.

TSRF

TSRF is the principal factor that affects production.

TSRF is a measure of the available solar energy in a particular location.
TSRF is affected by many factors such as:
- Roof tilt
- Azimuth
- Shading

DROPPING MODULES

In some cases, we may drop modules when the system sized at proposal will not fit on a preferred roof face such that either:

Modules would need to be placed on a low producing roof face such as a north facing or completely shaded out roof such as in the example below.
It is not possible to fit all modules from the proposal on the roof given restrictions such as:
1. Fire Setbacks
2. Mounting Restrictions in wind zones 1 & 2
3. Utility offset cap
If you are forced to drop modules, you must have a supervisor do a QA of the account to prove the drop is necessary.

Example:

This layout was completed in accordance with 2018 IFC setbacks. The system was sized at 11 modules (4.4kW DC) at sale, however, the proposal did not have any type of fire setbacks and was missing an obstruction on the preferred roof mounting plane.

The modules in red had to be mounted on a roof that is completely shaded out by distant forest growth.

For this reason, the designer has decided to cut costs and remove these four panels. Always be careful to add detail to your design-to-design validation notes describing why the system was downsized.

SAFETY OFFSETS

There are a few basic rules regarding roof layouts that will always apply:

Keep clear of obstructions.
Keep clear of the eave of the roof.
Keep clear of the ridge.
Keep clear of overhead service drops.

Remember, if no setbacks are required, then you don't need to show these safety offsets on the Plan Set, but you still need to factor them into the layout to avoid changes at install.

OBSTRUCTIONS

Default to a minimum of 6” clearance around obstructions.

EAVES

Default to a minimum of 6” clearance from the eave.

RIDGE

Default to a minimum of 1’ clearance from the ridge.

OVERHEAD SERVICES

Working clearance for overhead service lines is not mentioned in the IFC, however, it does pertain to the roof layout and is extremely important for the safety of our crews.

Must maintain a 3’ working clearance around the service drop.
Can still mount behind the service drop, just avoid mounting directly under or too close to the power lines themselves.

FIRE ESCAPES

Regardless of fire codes being enforced, we should always provide a 3’ path from any point of egress (Emergency fire escape such as a window). Pathway does not need to always be direct to eave (check jurisdictional requirements).

2 | INTRODUCTION TO AURORA

VISUAL LAYOUT GUIDE

AURORA SETBACKS

Aurora will allow you to set your defaults for fire setbacks.

Clearance of 6” from obstructions and roof edges are always required even when no fire setbacks are required.
Note that aurora does not know any fire code. It only knows how to do default setbacks. You still need to make educated decisions on fire setbacks.

AURORA MEASURING TOOLS

Aurora will also allow you to represent the location of electrical equipment and measure in 2D as well as 3D.

The ruler is useful for:

Rafter max span measurement
Home Run distance from the roof to the combiner equipment

Let’s take a hands on look at Aurora now:

Don't worry too much about accuracy with your model. Just choose a house and go for it!
Make sure to create a new design page for yourself to practice on

3 | ACCURATE MODELING

It takes a little bit of practice and intuition to spot inaccuracies with imagery. Be mindful of the following:

Accurate placement of buildings, trees, and obstructions
Accounting for image skewing utilizing the best aerial imagery possible.

LIDAR

Lidar is one of the most useful tools in aurora when available. What is Lidar?

A remote sensing method used to examine the surface of the Earth
Data is collected via airborne pulse lasers. This creates an elevation map of the terrain.
We can use Lidar data to create accurate tree dimensions, correct roof pitches and building heights.

Basically, Lidar can paint a picture of the landscape for you so that you don't have to guess what the roof/obstructions/trees should look like. Note that Lidar scans could be from a decade ago or more for some areas, so you still need to use surveyed data as much as possible.

Lidar is a tool used to aid your design only, it is not to be fully relied upon.

Sometimes, the lidar mapping function in aurora will not align with the aerial imagery for the sight. The lidar settings will allow you to adjust:

X-offset
Y-offset
Z-offset

This is the best way to ensure accuracy when utilizing Lidar.

NEARMAPS IMAGERY

Nearmaps imagery can help determine the following:

Location of roof obstructions and trees relative to what was captured during site survey
A detailed timeline of the property:
- Can show if trees present on lidar have since been removed.
- Can also help determine when new structures were built or identify new roof obstructions.

Aurora will allow you to select a map boundary and range of dated aerial imagery to use for the design.

Note there are costs associated with sourcing new aerial imagery. This will need to be approved by a supervisor.

MAP SPLIT/STREET VIEW

Aurora will also allow you to enter split map mode. This feature can be used for:

Spotting vaulted roofs and bonus rooms that weren’t surveyed.
Spotting the location of electrical equipment from the street.
Visual of tricky pitch changes.

BASICS OF MODELING:

Draw the outline of the home.
- When you're working with roof sections that are all sharing an attic space, most of the time, you can draw it as one shape and the smart roof function is pretty good at resolving all of the contours correctly.
Adjust the height of the Eave to the apparent height of the eave from the Lidar map.
- Don't worry about the height of the ridge. This will be corrected when you set the pitch for each roof.
Adjust the pitch:
- Use the surveyed pitch. If it is drastically different from what it looks like on Lidar, choose which ever pitch is less steep as this will assume less area for PV.
- Note that on most homes, each roof section will have the same pitch. Make sure to apply to the same pitch to all roof sections unless there is clear evidence otherwise (i.e. multiple roof pitch measurements, a clear pitch change on a roof, or contours that make it apparent that there are multiple pitches.)

QAULIFYING AND FIXING THE PROPOSAL DESIGN

In most cases, we can use the proposal design and adjust it as needed to be more accurate. There are times that you may need to decide to draw the structure comepletely over again if there are many missing nuances from the proposal design.

Start by determining any roofs that should be equal in length.
- Most gable roofs are the same length on either side of the ridge with a few exceptions like when there is a pitch change or level drop on the one side of the ridge compared to the other.

Sometimes it may not be apparent right away, and you may even need to use the ruler to get an accurate measurement when the structure has some more complex contours to deal with.
The dimensions circled in red are those that should be corresponding with an equal length measurement on the opposite side of the ridge.

Now we need to make sure that the model is correctly modeled to each edge of the roof.
You will need to bring the edges in toward the roof or out accordingly.

On this example, there are several roofs that need to be adjusted to be more accurate.

Make sure to look at every roof edge.

Now, we need to correct the pitch to what was surveyed.

There is no Lidar to compare with on this example.

When the pitch is corrected to be less steep, this means that there will be less roof area to work with overall, so it is important to get this right.

Next, ensure that all roof obstructions are accounted for on the roof that will be housing PV

We have 9 obstructions on this roof in this example.

There is one missing obstruction on this roof.

The missing obstruction has been added.
In addition, the obstructions have been moved to the correct location.

Don't worry too much about obstructions on roof sections we will not be mounting modules on.
- The obstructions in the red box represent obstructions that can be ignored since we don't plan to mount there.
Model EVERY obstruction in an accurate location on roofs where we ARE mounting modules.

Next we need to look out for trees and buildings that can cast shade on the roof with PV.

In this example, there are no trees or buildings tall enough to be a concern.

Now, we can get ready to design the layout.
Make sure to use the best default setbacks to help you make decisions about designating needed fire pathways when Fire Setbacks are being enforced by the AHJ.

In this example, we will be complying with 2018 IFC setbacks.

Now we can put panels on the roof.
Make sure to consolidate rows as much as possible.
- In this example, we have simplified to 3 rows.

Don't forget to plan your fire pathways.

Now we can string our modules.

ROOF EDGES

One small factor that can have a profound impact on roof area is accurate modeling of roof edges. When correcting roof edges, it is important to not include roof gutters as part of the roof area. This can add whole feet to some roof planes in some circumstances.

Model just to the "white line" of the gutter.
DO NOT OVERLAP ONTO THE GUTTER OR OVER IT.

IMAGE SKEWING

Image skewing occurs when the aerial image is presenting the home viewed from an angle:

Modeling will need to be adjusted in the opposite direction of image skewing.
Skew may be taking place in the X direction, Y direction or both.
When you see this, focus on modeling to the corners of the roof. Don’t focus on the ridge not aligning with the image. Remember, the ridge isn’t being shown correctly in the image due to skewing.

Before working on a skewed image, check if there are better HD images with less skewing. Always use the image with the least image skewing to complete the design.

When modeling on skewed imagery, use the following guidelines:

Make sure to model the eaves parallel. Focus on getting the corners in the right locations along the eaves.
For equilateral roofs, the interior ridges and valleys should be resolved accurately by the smart roof tool even though it will appear that it is not lining up with the image.

Hip roofs will have a less pronounced skew. Look at neighboring structures to rule our image skewing on hip roofs before drawing the home.

First, use the smart roof tool and line up all the corners as shown. In this example, we have roof sections of different pitches:

Worry most about the perimeter lining up with the footprint of the roof.

Next correct the pitches to what was measured during the site survey. Use lidar to corroborate this.

The key with hip roofs is:

Hips line up exactly with the corners
Hip lengths are consistent or uniform

If these factors are inconsistent in your model, revisit and redraw if needed. Avoid moving the ridge/valleys to match as it appears in the image.

COUNTING TILES AND SHINGLES

Whenever you are unsure of the location of roof obstructions due to image skewing or otherwise unclear aerial imagery, you can sometimes use the roof materials to help you measure out obstructions.

Note that this is easiest on tile roofs, but you may still employ this method to test on shingle or standing seam metal roofs.

Tiles roofs:

For flat type tiles, we can round up and call them each approximately 1' x 1'

Example:

For S & W type tiles, we will call this out as 16" x 10" then divide by 12 to get a final figure.

Shingle Roofs:

For all single types, typically, you can count rows of shingles with a spacing of approximately 5" and divide by 12 to get your distance in feet.
All shingles come in sheets of approximately 3' of length.
- Typically, you shouldn't try to do horizontal measurements using the shingle unless it is 3 tab where each visible shingle will represent 1'.

Example:

INCREASING OFFSETS

It is best not to guess locations of roof obstructions and dimensions of roof edges, so when it comes to image skewing, follow these guidelines to start with:

When the image skew appears to be greater that 1 whole foot, add an additional 6" offset to all roof edges and obstructions.
Add another 6" for each subsequent foot of image skew.

Again, ALWAYS try to source better aerial imagery when possible.

Example: This aerial image has significant image skewing. The designer has already shifted obstructions accordingly, however, the more preferred roof section (the one oriented upwards in the photos below) has some obstructions crowding it out along with some dormers. The designer has decided to use their discretion and increase offsets slightly.

A simple measurement shows that the skew is shifting everything over by over 1'

On this one, it will be safer to increase offsets slightly to overcome this.
- Remember, we want to design a product that can actually be installed.

This is what our final product looks like.

Let’s return to the model space we were working in before. Here's the link in case you lost it:

https://app.aurorasolar.com/projects/a35bf8a7-a1c0-461d-a029-a04c5387aa9f/designs/ca7a92df-a4e3-40a2-a127-48641b2453a7/cad

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Design & Engineering > Design 8.1 - Aurora Modeling

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