How Sun Number Is Simplifying and Automating Solar Energy Quotes

In recent years, the cost of solar power technology has plummeted dramatically, helping to make renewable energy far more accessible to consumers. However, the process of qualifying consumers and figuring out if solar makes sense for them still involves a lot of manual processes, a look by solar installers, often a site visit, and more--even if a homeowner's house doesn't make sense for a solar install. Denver-based Sun Number ( is looking to solve those issues, by using the power of computer algorithms and data to automatically figure out what homes ought to have solar power, and those which shouldn't. The firm's co-founder, David Hermann, sat down with us to explain what the company does.

What's Sun Number, and what's the idea behind the company?

David Herrmann: Sun Number was created about a year ago. We're truly a startup. The whole idea was to help people understand if their home or building has solar potential, and understand it in a very simple way. A lot of people can talk about solar potential in terms of kilowatt hours and other metrics, but quite frankly, the consumer has a hard time digesting that. What we've done, is create a numeric score--from 1 to 100--which indicates the solar potential of a building, with 100 being great for solar, and 1 being not suitable for solar. That was the premise we were founded on. We took this to the Department of Energy solar program about sixteen months ago, and they thought it was a great tool to engage customer, so they funded us with a Sunshot incubator award, which we used to build Sun Number scores in 10 cities in the U.S., and to see what kind of traction we could get with consumers and installers.

What's your background, and how did you end up working on this area?

David Hermann: Ryan Miller and myself are cofounders of the company, and we both came from CH2MHILL, a Denver-based company you're probably familiar with .We both worked together at CH2MHILL on a project for the Department of Energy's solar program, called Solar America Cities. As part of that program, we developed the very first, solar maps for a number of cities, including San Francisco, Salt Lake City, and Madison Wisconsin. That's where the technology really started. We left CH2MHILL after a couple of years, around 2010, and continued to evolve this technology, making it more efficient, and more cost effective. Eventually, we got it to the point where it is today, where we're able to process buildings at a fraction of cost it originally was, for mere pennies per building.

There are lots of solar installers offering to evaluate the solar potential of your roof, what's the advantage of your system?

David Hermann: That's a great question. What we really differentiate from them is, number one, we look at a rooftop and uniquely determine the pitch and orientation of the rooftop. And, probably, and most importantly, we're able to calculate the impact of shade from surrounding vegetation. We're able to look at a single family home, figure out that there are tall trees on the south side of the home which will cast shadows, and calculate using a time series analysis where those shadows are going to be over the course of a year. We're able to determine the impact that has on each square meter of a rooftop. No on else has figured out how to do that. That's the key parameter, shading. That determines the roof's solar suitability, and more importantly, where on the roof you would want to put solar panels on. I should also mention, we calculate the shade from the surrounding vegetation and the height of the trees compared to the rooftop. In urban areas, it's less about surrounding vegetation, it's more about taller buildings on the south side of a building you're looking at, and where those building's shadows will impact a given rooftop.

Are you doing that in an automated way, remotely?

David Hermann: Yes. There's lots of technical detail I won't go into depth on, but w're using data sets we acquired specifically for this. That data is based on LIDAR data, which gives you the elevation of surrounding structures. We understand the elevation of the building, the elevation and height of the canopy of trees, and using our time series analysis we can position the sun in the sky for that given building and calculate the shadows. This does take a computation significant amount of computers, running in parallel, to process all of this data. But, the end result is we get an enormous database, providing information on every building, for every single square meeting of every building. It takes fifteen computers running in parallel about two weeks to process half a million buildings, which is very computationally intensive. But, it's all automated.

What's the business model behind this, and is this something consumers or installers would use?

David Hermann: Consumers have access to their score, and the score is available to governments and nonprofits to promote solar, free of charge. However, what the business model really is for us, is making this data available to solar installers and the solar industry. Today, those solar professionals are spending, depending on size, thousands to tends of thousands, to millions of dollars on qualification of properties and individuals. What we're doing, is simplifying all of this information, making it more instantaneous, so that they can qualify properties. Not only can they determine the size of a solar sytsem that a rooftop can support, but how much electricity it could generate.

The Department of Energy is estimating that a typical installer is spending somewhere in the range of 25 to 50 cents per watt on the cost of customer acquisition. That's what they spend not just on generating quality leads, but also on qualification of properties. We can reduce that by about eighty percent. We estimate we can reduce that cost from 25 to 50 cents, to down to 3 or 4 cents, or maybe 10 cents. Those costs are a significant issue, because as the cost of panels has decreased significantly over the last couple of years, the cost of acquiring a customer and permitting have become a much larger percentage of the overall cost of solar. That's the area we need to focus on, in order to really reduce the cost of solar. We're focused very specifically on providing a significant cost reducation, not only on qualifying solar, but using our Sun Number as the tool to engage customers and produce more and better leads.