Sometimes good ideas take off right away. Nobody buys suitcases without wheels these days.

Other great ideas, however inevitable, need more time. Off-grid energy, running the gamut from solar home systems to microgrids in small villages, seems to have fallen into this category.

Former U.N. Secretary-General Ban Ki-moon launched the Sustainable Energy for All initiative in 2011. The U.N. launched its Sustainable Development Goals in 2015. Off-grid energy companies like d-light and Mobisol have been operating for years. 

Yet despite billions of dollars invested, and the backing of some of the world's biggest energy companies, the off-grid energy sector still has not scaled quite as much as many might have expected.

But things are finally changing very rapidly, according to industry leaders at Greentech Media’s first Off-Grid Energy Access Forum, held last week in London. 

All the signs suggest many of the thorniest barriers to scale have been overcome. Here are four reasons why experts say the path is finally clearing for electricity companies to reach "the next billion" customers.

1. Companies are focusing on what they’re good at

Many early entrants in the (largely) pay-as-you-go solar home system space tried to do everything.

Companies developing hardware and software in-house often wound up becoming manufacturers. Next they might have branched out into distribution and logistics, before also becoming a consumer utility and micro-financier.

Today, many vertically integrated players are narrowing their focus to what they're best at, while new entrants are tending to stay in one part of the value chain.

Trying to everything is "very, very hard," said Emma Hawkins, director of corporate finance at PEG Africa.

PEG Africa, a distributor of pay-as-you-go home solar systems, is about to expand to its fourth country, and it's done so without having to raise as much capital as some of its vertically integrated peers because it never ventured into expensive product development.

“You have to decide as a company what is in our DNA: Are you a product company or is it the financing?"

"The offshoot of that is that it becomes easier to explain what you are to an investor, if you're a distribution or technology or product company, and that allows you to tap into different kinds of investors," Hawkins said in London. "Your business model is more easily understood by investors."

Leslie Labruto, head of energy at the early-stage equity investor Acumen, noted that early vertically integrated companies had laid important foundations for the off-grid sector. She can see space in the market for companies taking both approaches.

“We wouldn't be where we are without some of those early pioneers making mistakes," Labruto said.

2. Big data making a big difference

Big data has come a long way over the past few years, and off-grid companies are increasingly making use of the gains.

Bboxx, another pay-as-you-go solar provider that recently landed an investment from Mitsubishi, said it's using data to better understand system performance in the field — helping to inform future investment and procurement decisions. 

The company is also using data to help "understand who are good customers and how we could sell more things to them.”

Consider a customer who — according to data sent back — might only be using half their home battery's capacity. Brianna Schuyler, who leads the data team at Fenix International, said such a customer could be informed about their spare power and potentially sold a radio, TV or other appliance that would improve their quality of life while making better use of their battery.

At the same time, the customer is developing a record of creditworthiness that gives off-grid companies more to bargain with when developing strategic partnerships. Over time, the data gleaned could itself become a revenue generator.

3. Demand is there in spades

Ben Attia, a research analyst at Wood Mackenzie, used Nigeria as an example to highlight the enormous market opportunity for off-grid energy systems.

The country of 190 million people has 13 gigawatts of installed generation capacity, but only one-quarter of that actually gets transmitted out to consumers, due to inoperative plants, line losses and other factors.

Unsurprisingly, citizens and business in the fast-growing economy are taking matters into their own hands, and there's an estimated 40 gigawatts' worth of diesel generators now running in the country.

“Nigeria's population is growing faster than the grid," said Alistair Gordon, CEO of the solar provider Lumos Global, which is focused largely on Nigeria. "The opportunity is enormous.” 

“Energy is very aspirational, and people move up what you might call the energy ladder,” Gordon told GTM. “They get a new job, they want a bigger TV, they need more power. So you have to have the flexibility in your solution to deal with that — people are changing.”

That means scalable solar and battery systems, as well as working with energy-efficient appliances to get the most out of the systems that are in place.

Gordon pointed out that in the time the solar-based off-grid energy market has been around, demand has jumped from lanterns and fixed lighting to fans, phone-charging and TVs.

4. Europe’s utilities helping local governments

Incumbent and often government-backed utilities in emerging economies could be considered a major hurdle impeding progress, Attia said. Their performance is woeful, especially in sub-Saharan Africa, where they’re bleeding money.

"When we started working with Zola Electric in Cote D'Ivoire, there was a huge pushback from government entities [and] national utilities,” said Valerie Levkov, senior vice president for Africa, Middle East & East Mediterranean at EDF.

“What we did, because we are EDF and doing lots in the country, negotiating with [independent power producers] for example — we came back with an argument," Levkov said.

"We told them to look at the cost — real cost — because if you compare the cost of appliances and the cost per kilowatt-hour, it is less than the lowest possible grid system cost. It's all about education."

Putting the ground work in early ensures you didn’t suffer at the hands of adverse regulation further down the line, Levkov added.

EDF partnered with Bboxx in Togo, where it also works with Zola Electric. And today, Togo is one of the countries that's clearing the path for off-grid, clean, distributed power at large scale. 

Support for off-grid energy now reaches all the way up the country's president, said Bboxx CFO Thomas Chevillotte.

As a result, local financing support helped negate dreaded currency risk, and partnerships with both local telecom companies and the post office gave it a step up in terms of distribution and logistics.

Next step: Go deep or go wide?

Lumos’ Gordon points out that while companies like EDF that “have the ear” of the governments are extremely useful for educating regulators and politicians, he views consumer education as even more important. 

As the sector looks to scale, that’s the big focus for Lumos. “The hurdle for us is consumer education," Gordon said. 

"Our target, or our competition, is a generator, a small generator. The generator exists because the grid isn't giving the customer what they need or is not reliable enough. But generators are very expensive."

"An on-grid customer is paying $50 per month, and an off-grid customer is paying $70 for fuel," Gordon said. "If they can get their energy from solar for $15 from solar, that's a big change. The challenge is education.”

The question of growth was summarized repeatedly in London as “go deep or go wide”.

The scope for the former, through added services, is huge. Once an off-grid company has a relationship with a customer, they can potentially deepen that commercial relationship in myriad ways, from health and crop insurance, which reduce the chances of a “shock” stopping a customer from making their solar payments, to telecom hardware and services, loans, cookstoves and water pumps.

Still, some experts are wary of complicating the offering before achieving a critical mass of customers.

Regardless, a host of a strategic investors are pouring money into off-grid energy access, from EDF to Shell to Uber. With funding, the proof of concept, a growing market, and reams of data coming in, the off-grid energy sector now appears to be pushing on an open door.