Several people told Robert Eckhardt he was crazy when he said he wanted to put solar panels on his company’s corporate headquarters nearly a decade ago. There were concerns about water runoff, high winds and the roof warranty, not to mention the fact that no one knew how to get the project financing done.

“To all of the naysayers who said I couldn’t do it, I just want to say I proved you wrong,” said Eckhardt, who serves as director of architecture and renewable energy at Bed Bath & Beyond, while speaking at the GreenBiz Verge conference this week.

Bed Bath & Beyond installed its first solar project in 2010. Today, the retail company has 17 megawatts of solar and recently committed to expanding its solar portfolio with an additional eight projects using SunPower’s new plug-and-play solar platform.

As prices for solar and wind continue to fall, more and more businesses are expected to turn to renewables to cut operating costs. Many companies are already leveraging their assets to deploy renewable energy projects on-site, as well as acquiring renewables off-site through power-purchase agreements.

In the first half of 2015, major companies signed a slew of renewable energy PPAs: Amazon signed a project for 150 megawatts, Apple signed for 130 megawatts, Kaiser Permanente signed for 153 megawatts, and Dow Chemical signed for 200 megawatts.

Commercial customers represent an enormous opportunity for renewable energy developers. But the corporate market has been limited to a small number of players.

Many companies, both large and small, continue to struggle with the economics and complexity of procuring clean energy. The Rocky Mountain Institute estimates that for every successful renewable energy deal there are five to 10 failed attempts or significant delays, which impedes overall market growth. Reflecting these challenges, the commercial solar market experienced its first down year in recent history last year.

Several companies leading the charge for clean-energy adoption presented on their lessons learned this week at Verge to help other businesses meet their renewable energy purchasing goals.

Use what you already have

For General Motors, renewable energy procurement turned out to be a natural extension of the company’s core competencies, said Rob Threlkeld, GM’s manager of renewable energy. The car company leveraged its experience tracking fuel prices to monitor electricity prices, and tapped its own electrical and mechanical engineers to help locate and build clean energy projects where it made the most sense economically.

“The biggest thing I highlight [to other companies] is to leverage the internal resources they already have available,” said Threlkeld. That applies to employee expertise and the company’s physical assets.

Having tested different options, on-site ownership of solar projects recently emerged as one of the most attractive business models for the automaker. GM has a lot of roof space to cover, and by owning the project, as opposed to signing a PPA, the company can claim the tax credits and reduce costs by cutting out the middleman. GM made its first direct purchase of a 2.2-megawatt solar array in Ohio last year.

In addition to buying solar, GM has contracted for wind, landfill biogas, and other clean technologies. These efforts have paid off. Overall, the company has achieved more than $80 million in savings through its clean energy programs since 1993, according to Threlkeld. Plus, there are additional branding benefits.

“Today, it’s possible to save money, or at least not spend extra money, and drive more renewable energy on the grid,” said Bill Weihl, director of sustainability at Facebook, which aims to get 100 percent of its energy from renewable sources.

“We want to use clean energy because it’s better for the planet, better for our communities and our employees, and we’re going to do it in a way that makes economic sense,” he said.

A key resource is the Corporate Renewable Energy Buyers’ Principles, said Weihl. The guide is designed to address what large energy buyers look for from regulators and energy suppliers, which includes independent developers and utilities in regulated and restructured states.

When companies approach decision-makers as a united group, "Suddenly they listen, because it’s a very clear economic issue,” he said.

Game-changing PPAs

The most important factor for corporate energy buyers is to have options. Companies want things like bundled renewable energy products, more opportunities to work with utilities, and increased access to third-party financing vehicles.

The renewables industry has already come a long way in recent years. In 2008, when Wal-Mart closed its first substantial wind-power purchase in Texas, “It was hard, real hard,” said Chris Hendrix, director of markets and compliance for Wal-Mart.

Wal-Mart, which historically signed one-year energy contracts, was not comfortable with a 25-year PPA. Conversely, developers were hesitant to take the risk of a short-term deal.

“As more people have gotten into the marketplace…developers have gotten used to the fact that it’s a negotiated price,” said Hendrix. “They’re OK with getting financing done, and the investment money is OK with doing a shorter-term PPA knowing they’ll be able to sell that in the future.”

In regulated markets, where traditional PPAs are prohibited, virtual PPAs have been a “game-changer,” said Christina Page, global director of energy and sustainability at Yahoo.

Under a virtual PPA, the company agrees to contract for a renewable energy project at a set price for electricity. If the electricity is sold into the local wholesale market above the contract price, the project developer pays the company; if the electricity falls below the agreed price, the company pays the developer. “It’s a hedge,” said Page.

“Even more than saving money, it’s about protecting against future volatility,” she added.

Virtual PPAs are less attractive today because of the low cost of natural gas, but projections show that prices will increase. Plus, in coal-heavy Nebraska, where Yahoo has a data center, there are concerns around mercury regulations increasing the price of coal-fired electricity.

“It’s likely you’ll be very much in the money in three years,” said Weihl. Facebook has signed several virtual PPAs for wind projects in Iowa’s regulated market.

Another tip is for companies to leverage the experts they likely already work with at firms like PricewaterhouseCoopers, Ernst & Young, and others. Many of these companies have already done the legwork to show how complex renewable energy deals work.

“Proving this isn’t snake oil or a Ponzi scheme has been huge in terms of getting conventional organizations to come up the learning curve with this so I can go to my accounting department with credibility,” said Page.

Always efficiency first

More and more companies are embracing the concept of corporate sustainability, which stands to expand the commercial renewable energy market beyond a few key players. But it’s not a guarantee.

Preliminary results from a recent survey of 400 corporate sustainability professionals conducted by Ingersoll Rand and GreenBiz found that around 90 percent of companies -- across small, medium-sized and large subcategories -- have made some kind of public sustainability commitment.

The survey also found, perhaps intuitively, that companies are more likely to pursue energy efficiency before making a commitment to adopt renewables.

“It really speaks to the efficiency-first principle, which is encouraging to see,” said Owen Smith, director of global energy policy and strategy at Ingersoll Rand. “But what I’m interested in seeing is what happens next. Will more companies take bolder, more aggressive action?”

For Ingersoll Rand, bold action means cutting greenhouse gases from its refrigerant products by 50 percent by 2020, and cutting operations-related emissions 35 percent by the same year. Smith said the company has initiatives underway to place renewable energy on its facilities, but Ingersoll has primarily focused its efforts on actions that are aligned with the company’s core competencies.

When it comes to renewables, there are concerns around contract structure, availability of incentives and cost savings. “I think some of those things, but fewer of those barriers, exist in the efficiency space, so that’s what we’re really excited about,” said Smith.

The evolution from efficiency targets, to demand response, to advanced goal-setting, to more complex on-site and off-site contracts is a journey many companies take, said Scott Wentzell, project manager for EDF Climate Corps, a fellowship program that places graduate students at major companies to advance their efforts on smart energy management. EDF has developed close ties with corporations through the partnership.

Despite the challenges and risks, Wentzell is convinced that the corporate sector is headed toward a tipping point on clean energy.

“Stay tuned for the next five years,” he said. “The Googles and Apples are proof of concept; they figured out how to do complex contracting, they invented the stuff. Now you're seeing companies making it vanilla.”