How Plentify Uses Hotbot & Solarbot to Solve Solar’s Timing Problem

What we talked about.

John Cornick, founder of Plentify, joins Sunny Ray to explain how solar energy's biggest flaw is timing, since it is generated midday but most demand happens mornings and evenings. Rather than relying on expensive batteries, Plentify's devices Hotbot and Solarbot shift when household appliances like water heaters consume electricity to match cheap, clean solar availability, without any noticeable change in service. Cornick traces his path from a South African upbringing during the end of apartheid, through management consulting, carbon finance work with South Pole Group, and running Google's African energy investments, to founding Plentify nine years ago. He describes an early pivot after Cape Town's Day Zero water crisis crushed his original solar water heating business, pushing him toward a first principles realization that timing, not just energy source, was the real problem. The conversation also touches on Bitcoin mining economics, first principles thinking, and lessons learned transitioning from consulting to product driven iteration.

Plentify's founder explains how shifting appliance timing, not batteries, solves solar's biggest flaw: it shines at the wrong time.

The questions, and the answers.

What problem is Plentify trying to solve?

Solar is the cheapest form of generation ever, but it shines during the day while most people, especially residential users, want electricity in the mornings and evenings. This mismatch could be solved with batteries, but those are expensive. Plentify instead controls home appliances to shift consumption to align with cheap, clean solar times, with no noticeable difference to the homeowner, just a lower bill and lower carbon impact.

What was your role at Google and what did you learn there?

I worked on Google's green business operations team, helping run their African energy investments. We invested in what was then Africa's largest solar farm in South Africa and largest wind farm in Kenya, later moving into energy access. I learned the value of a beginner's mindset, approaching risky, complicated projects from first principles rather than being fettered by industry status quo, which let us close deals others had stalled on for years.

Why did you leave Google to start Plentify?

I saw that most African energy activity focused on big grid projects or tiny energy access systems, but little was done for the majority already connected to a grid but suffering expensive, unreliable power. I believed pay as you go models and advances in IoT and AI could address this segment, that it wouldn't move the needle for Google, and I had a healthy dose of delusional optimism as any entrepreneur needs.

Can you explain what first principles thinking means and how you apply it?

It means not solving a challenge directly but understanding its underlying drivers and root cause, then solving that. For example, if told a project's risk adjusted return wasn't high enough, we'd go understand all the risks and what they truly cost, rather than accepting the incumbent view. Coming in without established industry knowledge forced us into this approach, which became an advantage.

How did you realize demand side timing, not just generation, was the real opportunity?

We originally helped homes upgrade from electric to solar water heating, growing well until Cape Town's Day Zero water crisis hit and hot water consumption dropped 60%, crashing our revenue. That forced us back to first principles, and we realized the real problem wasn't the energy source per appliance, it was timing. Shifting when appliances use electricity to match solar availability solved it without adding new hardware.

Have you considered using Bitcoin mining in your energy systems?

In places like Texas with negative or very low electricity prices, mining Bitcoin can be viable since rigs can ramp on and off with real time prices, though you still need high utilization to pay back capital costs. In South Africa, our calculations show it doesn't make sense versus other productive uses of excess energy, which we're exploring and hope to launch within the next month.

Can you explain how Hotbot and Solarbot actually work?

Hotbot connects to your electric water heater, learns your hot water usage and how your heater stores energy, then heats water only as much and only when needed. Solarbot connects to your solar inverter, maximizing battery charging from solar. When your battery is full and there's excess solar, Solarbot wirelessly tells Hotbot to turn on the water heater so that extra solar isn't wasted or sold back at a poor rate.

What advice would you give your past self about to leave Google?

I probably wouldn't tell myself much since delusional optimism was part of my power in those early days, and I wouldn't want to dampen that. What I would say is change the way you think: I wasted early time using a consulting style hypothesis driven approach, when building a product business requires a more iterative, product design thinking approach instead.