Using Roof Effectiveness Score to Qualify Leads

Introduction

The Roof Effectiveness Score (RES) is a feature exclusive to SolarNexus. Using only an address, the RES gives you an objective measure of a given roof's effectiveness for a PV system installation. The RES is a ratio comparing the effectiveness of your prospective customer's roof to an ideal roof for this location. It can be used in the earliest stages of lead qualification, when only the site location is known.

What is 'Effectiveness'?

The most effective roof for a PV system has a score of '100' and is defined as a single roof segment that is:

• located in the customer's weather zone (shares same solar resource, temp, wind, etc)
• large enough to fit whatever size array is needed to offset 100% of the customer's annual usage
• perfectly oriented south with a tilt equal to the site's latitude
• not affected by any shading

This Of course no roof is perfect. The factors that reduce a roof's effectiveness include:

1. The quantity and size (sq ft) of roof segments needed to accommodate a given PV system size. The more roof segments, the smaller their size, meaning less space available to place modules. Design and installation costs rise significantly with more roof segments (note that each roof segment is assumed to be its own array)
2. Orientation of each roof segment - Its tilt and azimuth, which determine the energy productivity
3. The shading cast upon each roof segment throughout the year.

SolarNexus considers ALL of the above factors in it's Roof Effectiveness Score. Since these factors are the primary drivers of financial returns when all else is equal, the RES can be an effective tool for quickly assessing prospective customer leads.

Using the Roof Effectiveness Score - examples

Let's look at some examples of how the RES can be used to help set lead quality and/or disqualify a lead.   Say a potential customer calls the office and the insides sales consultant creates a new lead in SolarNexus.

After confirming the site's location on the map image, RES values are automatically computed for a range of system sizes - from 2 kW up to an estimated maximum array size which can fit on the roof.  The Roof Effectiveness score is presented as a line graph with system size on the x-axis. Note that RES values will always stay the same or decrease as the system size increases, because as system size increases, modules must placed in less sunny places or even oriented north.

The RES charts and roof images for these examples are shown below.

Immediate Disqualification

You can use the RES to immediately disqualify some leads. For example, see the example below. If you just look at the house, you may not be able to tell how shaded it is during the year. The RES shows that even the smallest size system will not do well on this roof.

Potentially Qualified, But Lower Priority

In the example below, the roof has enough room to fit a small array with good solar access. But as arrays grow and roofs are added, the quality of the system degrades rapidly.

Hovering over a point in the chart displays the RES score for PV system sizes in kW, and the number of arrays (or roof segments) required.  Here we can see a system size of 4 kW consists of a single array with an RES score of about 86, which is in the yellow band just below the threshold of what is considered a roof with excellent effectiveness.

NOTE: The threshold values for good/excellent, and good/unacceptable can be configured by an administrator in your company account.

In a case like this you'll want to find out if a small system will be adequate for this customer, but because you can only do a small system that is effective, you may choose to de-prioritize this lead.

Effective Roof, Qualified and Prioritize

The example below shows that the trees in the front of the house are not an issue for the large south roof face. The roof has an excellent score up to about 7 or 8kW before degrading.

In this example, the customer had a recent utility bill available, so the sales rep was able to input Energy Use from a single customer's bill.  After inputting the customer's energy use, the rep returns to the Site Definition screen and the RES chart now shows an estimate of the system size needed to offset 100% of the customer's annual use, as shown here:

In this particular market, residential arrays are typically sized to 100% offset, or 7.7 kW, which will require two arrays are shown on the chart.  The RES value at this size is 89, which makes the roof's effectiveness very good.  Using this RES score, along with other data available on the Site Definition screen, such as the street view, tilt view, the inside sales consultant sets the lead quality at 2, assigns a sales consultant, and completes the Qualify Lead milestone. 

The sales consultant may make use of the RES Chart when initially creating areas and PV arrays.

RES Behaviors and Limitations

• If you wish to recalculate RES values for an existing project, you must unconfirm and reconfirm the site location.
• Projects existing prior to release of the RES feature are assumed to have confirmed site map locations, however the RES will not be calculated until you manually go to the site definition screen and hit "calculate".
• Calculation of the RES values depend on Google's Project Sunroof data, and not all of the US is covered.  Also note that Project Sunroof data may be a couple years old, and therefore may not reflect new building construction or the growth of trees.
• The RES assumes modules will be mounted flush to the roof surface.  For flat roofs, this will underestimate production tilt-up arrays.