Dennis Krul
About me
I'm a tech enthusiast and a nerd, living in Delft, the Netherlands, with my wife and three kids. I'm director of operations at a large hosting company, responsible for the teams and the roadmap behind its servers, storage, virtualization, networking and datacenters. I engineer software, but I wouldn't call myself a software engineer: I build things to make computers do what I want.
My job is no longer hands-on, so I tinker at home and try to keep up with new tech. My main project right now is EMS, the energy management system for my home battery; its stats are on this page, and the Dutch electricity prices it works with are under Energy.
I care about digital sovereignty. I've always been an open-source and self-hosting guy: I'd rather fix my own things, own my data and keep it private than depend on someone else. That doesn't make me against SaaS or commercial software, but I'm always looking for the free alternative, free as in freedom. Open source is about community and freedom, not just published code, which is why I'm still waiting for a real Linux phone.
Away from the screen I make and mix music: house, techno and some trance. I started DJing on old turntables at fifteen and making tracks in ModEdit, then Scream Tracker 3, FastTracker, Renoise and Ableton, and now Bitwig Studio on Linux. After 25 years I sold my Technics 1210s for a digital setup, only to find that beat sync makes DJing a bit too easy. So these days it's more about making music, and one day learning to play keys properly.
It all started when I was ten, writing GW-BASIC on MS-DOS. At fifteen I ran a BBS on FrontDoor and RemoteAccess. Then came an always-on cable modem and Slackware, and a Linux box that was my home network's gateway and its web and FTP server. PHP 3 followed, and Linux and the web have been my thing ever since, at home and at work. Along the way I worked on Solaris, HP-UX, AIX and Tru64, and ran Linux on IBM mainframes.
In 2007, when virtualization was the new thing, I started a VPS company with two partners, on a platform we built ourselves: PHP on Xen and KVM, fully self-service and automated. We opened to customers in 2009, and in 2018 I sold my shares. Since then I've been a product owner, a Linux team lead and an IT architect, before moving into my current role.
The best way to reach me is on LinkedIn.
Home energy
My home battery is run by EMS, the energy management system I built: it charges when electricity is cheap and discharges when it is dear, around the solar panels and the dynamic price. What it came to, through 31 October 2026:
- Battery saved
- €351.82
- Solar value
- €1,856.40
- Net energy cost
- −€181.94
- Battery cycles
- 203
- Round trip
- 71% last 30 days
| September 2026 | October 2026 | All time | |
|---|---|---|---|
| Battery saved | €40.05 | €20.31 | €351.82 |
| Solar value | €192.04 | €184.70 | €1,856.40 |
| Net energy cost | €33.31 | €142.63 | −€181.94 |
| Battery cycles | 19.9 | 10.2 | 203.4 |
| Charged at | 19.5 ct | 20.7 ct | 17.0 ct |
| Discharged at | 40.1 ct | 44.7 ct | 32.6 ct |
| Spread | 20.6 ct | 24.1 ct | 15.6 ct |
| Round trip | 82% | 70% | — |
Battery saved is what its discharge was worth less what charging it cost; solar value is the power generated, valued at what it displaced or earned; net energy cost is grid import less export revenue, so below zero is money earned. Prices are per kWh. Round trip is the energy the battery gives back per kWh put in. Whole days only, updated daily. All time is since 24 February 2026.