History

Things that happened before and where the latest workgroup formed.

The Alternative Power Network

How it started...

At CCCamp2015 we had the idea to build a small DC grid suitable for being used at events where normally diesel generators supply most of the power. We started designing for two years in our spare time. We wanted something safe, simple and transparent where everybody can be a supplier or a user of electric energy. For safety reasons we chose a voltage of 42V (+/- 15%), a bit below the "safe to touch" voltage maximum of 60VDC (IEC 62368-1:ES1). This way there is a bit of headroom for the over-voltage protection circuit which is needed to protect the users. Still leaving some extra volts headroom for cable losses was a thing we wanted to have just in case too. Simpleness was achieved by not doing too much complicated stuff with end-user connections. No monitoring of energy consumption or under-voltage protection was implemented. Just the basic necessities such as over-current protection (4A type C 300VDC circuit breakers) and over-voltage protection. (The last being a 600A peak capable thyristor based crowbar that shorts and isolates a node above a 52V voltage peak on the grid. The crowbar has a 0.16F 63V capacitor bank for guaranteed triggering that doubles as a smoothing capacitor for the node as well! A bonus is that it really helps keeping it ES1 as it keeps AC ripple to a minimum!) Transparency is important, the old website explained how the grid works and what users can and can't do with it. People started building nice things at home before the SHA event, connected them to the grid and all of it worked after maybe some finetuning!

At "Still Hacking Anyway 2017" the first test grid was laid out. It was running for the duration of the camp without any big issues. Solar panels were attached, tea was made with solar power, bread was toasted, lithium batteries were charged and even a 48-300V (2500W) bi-directional DC-DC converter setup was tested. TDK-Lambda was kind enough to supply us with two of those fantastic units. More about that here!

On Hackaday there is a nice article too about how the grid was used. Of course there was much to improve, battery backup would have been nice for instance, but it did work as expected and nobody got electrocuted!

Now the whole setup is dismantled again. It just was too heavy, took up too much storage space and it's just what should happen to an experiment for new and improved experiments to follow. So we'll be back!

What happened to the old website?

Due to a personal error of mine, the website was not backed up properly... I didn't realize my error and took the site down. This site will be held up as long as possible. Backups will be tested for completeness too. Fortunately the Wayback Machine has backed up a good deal of pages! Still relevant data will be put on this wiki too!

Update: There is a almost complete resurrection of the old webiste available at http://altpwr.archive.tiefpunkt.com/