Palm Springs, Calif. --- After a bruising battle over feed-in tariffs, our second fight of the day, in the smoke-filled Solar Summit arena, was between Danny Kennedy of Sungevity and Tim Keating of Skyline Solar.

This skirmish, in the upper weight classes, pitted supporters of rooftopsolaragainst fans of ground-mounted distributed solar.

Here's the highlight reel:

In support of rooftop solar

Danny Kennedy, the founder of Sungevity, charged out of his antipodean corner and asked, "Do we want to scale?"

"Ground mount tends towards central generation and that looks like inheriting the legacy of bad fuel choices like nuclear and coal."

Kennedy reduced it to two words: "Net [expletive deleted] metering."  Technically, three words.

"This is why rooftops are so attractive," insisted Kennedy. "Instead of going out to the desert and competing with wholesale costs and competing with coal and nuke, you poor buggers, you put it on a roof, you get thanked, and you don't have to pay a Mojave dirt farmer for some patch of desert." He went on: "You don't get exposed to the billions of [dollars of] underinvestment" in transmission resources, according to the potty-mouthed founder.

"I pity you poor people who have to get through BLM or the suits at the Sierra Club -- that's why 'braggawatts' never happen."

"Don't replicate the mistakes of the last two centuries," urged Kennedy.

He then went for the knockout, saying, "Sungevity has 5 megawatts on the roof -- we're going to address a 40-million-unit addressable market which has only addressed 120,000 units so far."

In support of ground-mounted solar

Tim Keating, VP of Marketing and Field Operations at Skyline Solar, broke it down:

"It's a matter of cost. Let's say you need ten kilowatts on the roof. It's going to cost $5.00 per watt and it's going to cost $50,000. In the field, it costs $30,000."

Keating's point: "Someone has lost $20,000."

The flurry continued. "On a roof, you'll produce 10,000 kilowatt-hours annually; in the field, about 20,000 kilowatt-hours."

So -- a roof produces half as much power energy at almost twice the cost.

"It works only because of our policy," said Keating, adding, "This is real economics versus giving rich people a feel-good sensation."

"The roof faces the wrong way -- or the roof needs a new roof," while ground mount "doesn't mean centralized solar." It means "high capacity solar" that doubles the capacity of Kennedy's roof.
 
Keating urged the industry to "strip away all the policy shenanigans," explaining, "We have to install terawatts, not megawatts. We will not get to gigawatts of solar on people's roofs, especially when those houses get demand charges."

The industry is "going to grow on the ground and connect to the distribution grid," because "the lowest cost of capital and the lowest O&M is not on the home."

Kennedy countered, accusing Keating of being "stuck in the mainframe mindset" and noting that solar roofs actually protect residential roofs. Kennedy then went for the heart: "We don't want to be like Altamont, a big industrial disaster [like nuclear]. We can touch people's lives" so they can be part of the solar revolution.