That Decentralised Low Voltage Local DC Power Grid, How Did It Do?


Early on in the year, Hackaday published one of its short daily pieces about plans from the people behind altpwr.net for a low voltage DC power grid slated for the summer’s SHACamp 2017 hacker camp in the Netherlands. At the time when it was being written in the chill of a Northern Hemisphere January the event seemed so far away, but as the summer fades away along with the deep tan many SHACamp attendees gained in the Dutch sunlight it’s worth going back and revisiting the project. Did they manage it, and how did they do? This isn’t really part of our coverage of SHACamp itself, merely an incidental story that happens to have the hacker camp as its theatre. 

A Working DC Power System

The SHACamp 2017 solar array when the sun was out.

As someone with an interest in DC power their village was high on my list of priorities even if its distance from the UK hackspaces village was too high for me to have my own supply. What I found when I made my way over in the persistent rain of the first day was a fully functional DC power grid, albeit not as ambitious a deployment as that planned when first we reported on the project.

Power came from a set of solar panels, each with an onboard regulator to the grid’s 42 volts. These were concentrated in a central distribution cabinet, from which was fed a sub-cabinet for distribution to villages and other users. The plan for a full-scale grid is to have a network of such cabinets, however the huge logistical challenge that posed for a team of volunteers on their first deployment meant that the system on show was considerably more modest.

Peering inside the cabinets revealed arrays of circuit breakers and custom boards for current monitoring and voltage regulation. The cabling in use was not of the size you might expect, because of the relatively humble size of the installation it appeared that they were using hefty mains cable as the current in question was within its capability.

Regulator and charger on the other end of the wire in the ChaosWest village
Regulator and charger on the other end of the wire in the ChaosWest village

It was time to follow one of the cables snaking a few hundred metres across the grass of Scoutinglandgoed, which took me to the Chaos West village, and incidentally to an encounter with an awesome propane campfire and some of the best popcorn I have ever tasted, but that’s another story. There I found their endpoint, and a home-built regulator providing a step-down to a variety of voltages that they appeared to be using for both LED lighting and to charge the batteries for their array of electric vehicles. They had a reported voltage drop of over 10 volts over their cable run, an inevitable result of both its length and comparatively small cross-sectional area of copper. They did however have a useable power supply, and were taking advantage of it.

It was clear from the SHACamp 2017 DC power grid that this was a fully functional operation able to safely generate and distribute electricity to the attendees in a manner that they could take advantage of for simply the cost of a commercial switch-mode converter board. It was obvious though that this was a limited deployment within the logistics available to them in the run-up to this event, but what it gives us is a preview of what we can expect at future events.

A Viable Proof Of Concept

In particular the key word missing from the SHACamp deployment is in the title of this piece. Decentralised. On this occasion there was only what amounted to a power supply node, or a power station if you will, and customer nodes. You might say that this was the very model of a centralised power system, the shortcomings of which were laid bare in an obvious manner by the voltage drop at the Chaos West village. Happily though it’s important to stress that this is not a problem of design but one of the logistics of this first deployment. The system is designed from the ground up to be supplied from an array of power sources from “official” power nodes to users feeding their own power back into it, and this offers us the exciting prospect of future camps featuring a more extensive and robust DC power infrastructure building on this one but with less concern over voltage loss.

When reviewing the DC power grid at SHACamp 2017 it is therefore best not to criticise it for any shortcomings it may have had. Instead we should view this outing as a proof of concept of an exciting development that will feature in future camps. It is not a demonstration of the limits of what the altpwr.net people can do but a taster of what is to come, and that can only be exciting.

More information about the grid including significant technical detail can be found at altpwr.net.



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *