This applies for example when you want to add a photovoltaics installation to your campervan, expedition vehicle, garden hut, off-grid house or similar. For having enough electricity year-round from photovoltaics alone, battery size and module size have to be properly dimensioned.

The best tool I found for this is the European Commission JRC's PV potential estimation utility. There, use the last tab "Stand-alone PV".

Note that that the tilting angle of the solar panels is important in winter. Differences of up to ca. 30° from the optimum have no large effect, but above that they get quite important. So having an angle of 0° (flat panels) while you should have an angle of 74° (Germany in winter for example) means you get only about 25% of the power you would get at a 74° angle. You can calculate the exact numbers for this with the SunAngle calculator.

It seems like this:

  • The lashing capacity LC according to the norm (EN 12195-2) means the maximum allowed force on the strap in straight pull.
  • When buying lashing straps, you might get an additional second LC measure that is double of the normal LC. This is the lashing capacity in round pull.
  • Why is round pull LC double that of straight pull LC? Think of an application where you connect two points have 180° deflection of the lashing strap (around a tube or similar) at each, in effect making the lashing strap go a full round. A model for this is a small set of pulleys with two barrels and double string. Each of the strings of the one lashing strap (one going forward, the other going back) now has only to bear half of the force between these two points that you pull together, which doubles the lashing capacity compared to straight pull. And as in a pulley system, the force on the belt is the same everywhere as it can distribute evenly, so the part in the 180° deflection point also bears just half the load of the full system.
  • To make the confusion complete, there is a code concerning straight line seams on the lashing straps. They are called “ton lines” (German: Tonnenstreifen) and people think that they indicate: one stripe per 1000 daN lashing capacity in round pull (not in straight pull). But I have yet to see the norm text for that and could not find any source (Hey regulators! You still don’t have these as open content? C’m on, nobody wants to pay 224 USD for the EN 12195-2). In case of lifting loops, they are called “load bearing capacity stripes” (German: Tragfähigkeitsstreifen) and there, indeed, one stripe seems to mean 1000 kg of capacity, but in direct pull.

See also another (German) site with explanations of the lashing strap norm’s abbreviations (LC, HF, SHF, STF, BF, BFmin).

Before using information in this text for security critical applications, check the facts for yourself. I do not take any responsibility!

Currently I'm building the first parts of my truck's furniture system. The system is based on gridbeam, an awesome simple DIY construction system from the 1970's. Practically this means: boxes, room partitioning walls, shelves, desks etc. all use the same sheet material and connector elements and with the same compatible hole pattern, so one can build everything from the same set of elements, and can reuse the parts from a no longer needed object to build something else. Or reconfigure the furniture according to current demands, using an inbus wrench.

I'm starting to build my furniture with some simple storage boxes that will be secured to the wall in several layers, yielding a big 70 cm deep shelf for general storage. Both this box system and gridbeam itself are detailed in the interface specs part of the EarthOS document. But here's a quick overview of my design choices:

  • Compatible with ISO pallets. Size is 700 x 350 x 350 mm, together with with handles and corner elements etc. up to 800 x 400 x 400 mm is allowed.
  • Same size walls. The basic wall size is 350 x 350 mm, and in this case I build double-depth boxes, so some walls are 700 x 350 mm. These larger walls could also be created by combining two of the smaller walls with aluminum sheet metal connectors; and likewise for even larger boxes. To allow creating a box from just same-sized walls, the walls have 45°  beveled edges.
  • 50 mm gridbeam system. This means, all sheet material has a 50 x 50 mm hole pattern starting 25 mm from all edges (holes are here only around the edges, more holes can be added on demand). Holes in boards are 8.5 mm for M8 bolts, but in the case of boxes fitting for M6 sleeve nuts. Holes in aluminum connector elements are 6.5 mm for M6 bolts.
  • Modified hammer-in nuts. I really had a problem finding reasonably priced sleeve nuts for going into the board holes – I'm just not paying 1 EUR and more for one lathed sleeve nut, that would be 55 EUR per box for 'em alone. So I finally tried ordinary M6x8 hammer-in nuts with their four spikes, and just cut away the spikes with tinsnips. By letting 1 mm of the spikes in place, these nuts will not even free-rotate when at the loose end and turning a bolt into them. They have enough grip in wood that way, while the sheet wood and the nut is still reusable infinitely (which was not the case with the spikes in place).
  • Bolts used. Currently M6 x 13 stainless steel (A2-70) bolts with inbus head. Used together with a washer to secure the bolt against loosing and to better distribute the force to the (relatively soft) aluminium sheet metal.
  • Apt for cheap and salvage materials. I'm currently creating the corner elements from simple aluminum sheet metal that I had lying around and that can be had from the local recycling yard nearly for free (as in free beer, not as in FREE BEER). Using 50 x 50 mm and 100 x 50 mm aluminum L-profile is also possible and looks better (examples in second picture) but is of course more expensive and less autarkic. Also, one can use many different types of material for the box walls: any thickness will fit because of the beveled edges and because the box's outer measures are standardized, not the inner ones.

Writing this I realize how trivially simple this design is. Yet the simple ones are hard, for whatever reason. I had developed thoughts for the box system over months, and even started building one variant which was way too complex and too expensive. The current variant emerged after some great, inspiring discussions with my Dad on the matter. (I should know where my hacker genes come from ;))

And here are some pictures of the current progress with the boxes. (Some parts are obviously still missing: corner elements for stacking, handles, a flap, locking bolts.)

See this unrelated item in the media gallery? It's a rare Thermoflash fluid-heated jacket that I got as a bargain on eBay. Can keep everybody warm through German winter. Yep, really everybody 😉 Normally used on motorbikes and connected to the engine's cooling circuit via a heat exchanger and digital temperature control.

Oops, no wheels :) But we're checking the brakes.

Here’s a little page with images and videos from the make-a-truck-my-home project that I have going on since … well, too long already 🙂 Enjoy!

A video of the raw box body the morning after we transported it home:

And a video of driving the truck to the petrol station immediately after buying it:


On (Mon) 2009-02-23, I … umh, say, attended a wedding. A wedding of my 4WD truck and its box body (German: “Kofferhochzeit”). That’s at least the jargon in my favourite 4WD truck forum. Then, on (Wed) 2009-02-25, the vehicle with its new body moved places and is now just below the window of my li’le flat. Very cool, because now I can work thereon whenever I’m bored of programming!

I’m gonna show you some pics of the “wedding”, but before, I need to place an “honorable mention” here: Micha, a friend of mine, really helped me in the substantial portions of preparing and executing the box body mounting. All the things that I either am not able to do or had too little experience yet: re-welding the box body subframe after decreasing its width, helping in the mounting procedure with that crazy lift station you see in the pics etc.. And, what was also very cool, he let me use his workshop and tools whenever I worked on the body or vehicle. And let me use parking spaces for the truck (for 3 months) and its body (for a year) before finally both went off together. Not to mention that he found both these perfect offers (box body and vehicle) on his journeys through resp.

Well then, the pics:

This one shows the setup before the start of the body mounting.

Yay, cool lift. Comes in very handy.

Finished, but all the tools laying around in a total mess still … 

The truck just before it left its place on (Wed) 2009-02-25. The back flap came in handy already, to load all my tools and stuff in it.

In L.A., approx. 8% of the population is living on the streets, sleeping in their cars [source]. Which is, to a significant part, an effect of the financial and economic crisis. (The L.A. numbers are the highest in th U.S. … I’m not writing here that this is a nation-wide phenomenon in the U.S.)

Wait a moment, what’s wrong with sleeping in your car? 😉 Hey, of course, I pity those who need to do and don’t want to. Some however, including me, want to do so deliberately. It takes you to a higher level of spatial mobility if your house has wheels. And to a higher level of financial mobility, as you can drastically reduce the running costs.

Reading the L.A. numbers of homeless people makes me think that those crisis effects might come to us also. Perhaps 1-3 crisises [uh … sic?] later than the current one. And, it made me think: I’m not gonna fall in crisis if I’m living already as if I had fallen in crisis. Noone will drive me out of my home to sleep in my car … I’m doing this already! (Well … at that time. The motorhome project is not yet through, you know.)