Energieversum sells residential and small-business solar and energy systems through a nationwide network of independent field sales representatives. Its approach to building that salesforce is built around quality rather than volume: it accepts roughly one in ten applicants and invests heavily in preparing each of them for the job.
New representatives get intensive, hands-on support from team leads who were successful salespeople themselves. That is central to the model — the people developing new reps know firsthand what a successful customer conversation requires. But it only works if every representative is ready before meeting their first customer, which makes onboarding part of the growth strategy rather than a support function.
The challenge
Energieversum's onboarding combined an online academy with weekly one-to-one roleplays and frequent group training. The academy could teach theory at scale. Practical sales training could not.
Not everyone could actively take part in a group session, and when new representatives practised with each other, both were still learning — neither could give the quality of feedback an experienced team lead could. The most valuable sessions therefore depended on the strongest salespeople in the company.
Each one-to-one session could run to 90 minutes. In that time a team lead had to play the customer, respond realistically, watch the representative's performance, and then give detailed, objective feedback. Delivering enough of those sessions manually would have consumed so much capacity that, by Marc Weißbrenner's estimate, a team could realistically onboard only one new representative a month at the required standard.
A general-purpose AI chatbot was tried. The appeal was immediate — practice on demand, and engaging — but it broke down after a few exchanges: it lost track of which role it was playing, and sometimes started selling the product back to the representative it was supposed to be training. Turning that into a structured programme would also have meant team leads writing and maintaining their own prompts, scenarios, scoring criteria and records.
The solution
Setting the programme up was a focused briefing rather than a development project. Energieversum and Sleak mapped the real structure of the door-to-door process: the first knock, discovering what the household needs, presenting the right solution, arranging the appointment, following up.
In each scenario the AI stays in character, follows the context of the conversation, and raises realistic objections. The assessment criteria are the ones Energieversum's own coaches use rather than a generic sales rubric, so every conversation is scored consistently against a detailed Scorecard — questioning technique, conversation structure, speaking pace, filler words, language that weakens the message. A team lead playing the customer cannot watch all of that at once.
The heaviest use is at the very start of the process: making first contact and securing an appointment. It is the first thing a new representative has to master, and it needs far more repetition than a weekly roleplay can supply.
Team leads no longer run every roleplay. They review the structured feedback, listen to recordings at double speed where it matters, and spend their time on the representatives and the moments that genuinely need a human coach.
Results
Before Sleak, many participants arrived at the final onboarding day having practised between one and ten sales conversations; ten was already exceptional. Today a representative completes around 35 on average, and some report as many as 50 — at least a fivefold increase in practice volume.
The time commitment has fallen just as sharply. Weekly one-to-one sessions that used to take about an hour now take roughly 15 minutes. Across six or seven sessions, that is at least five hours of team-lead time saved for every representative onboarded, and that capacity goes back into recruiting, targeted coaching and supporting more people. Marc estimates it lets Energieversum build its sales organisation about twice as fast.
New representatives also walk into their first real conversation with far more repetition behind them. The hardest moment — the initial cold approach — can be practised dozens of times, with specific feedback each time, instead of being learned in front of a customer.
The amount of time we save is incredible. The one-to-one roleplays used to consume the time and expertise of our best team leads. Now we no longer need them to run every practice conversation — and that is a gigantic advantage.
Marc Weißbrenner, Head of Field Sales, Energieversum
