Solar Powered Wireless Laptop Web Server

I got my laptop wired up to my solar panel this afternoon. (photos)

This web page is hosted on the laptop featured in the photos... so it might go off-line without notice. :)

The panel is a set of 42 Siemens/Arco commercial-grade cells probably running at about 14% efficiency. The cells are nominally 0.57 V open-circuit, 3.0 A short-circuit, so the power would be somewhere lower than the ideal 1.5 W/cell. Each square cell is just a tad over 10cm or 4" on a side.

The original wiring was one string in series, making it about 24 V open circuit, 3.0 A short circuit. I rewired it to have 2 parallel strings giving me 12 V open circuit, 6.0 A short circuit. With the laptop hooked up, it ran at about 10 V, 2 A, with the current rising to meet demand. This was not ideal and would have been operating in it's more efficient band if it were a 12 V nominal panel at maximum power.

As you can see, the system isn't quite for production yet... It could use some silicone to attempt to waterproof it and a sheet of plywood to stabilise it. The meters are interesting, and it would be interesting to get a analog-digital converter to get stats live on the laptop. :)

The laptop is an IBM A21p. It idles at about 20-25 W full screen brightness. Charging seems to make a difference of about 5 W.

The maximum draw I have seen from the solar panel was around 30 W, full brightness, charging the battery, wireless network, playing sound and disk access all at the same time. I didn't try adding more devices such as spinning up the CDROM or adding USB devices...

Shutting off the display reduces idle to 11 W, running at the dimmest screen setting is about 15 W.

I even took out the battery at one point to convince myself that it was working as assumed (and made sure I or the cats didn't walk in front of the panel, shading it).

The IBM AC adaptor is rated at 150 W in AC, 72 W out DC max. The IBM auto/air DC adaptor is rated 136 W in DC max, 72 W out DC max (57.6 W nominal).

I would really like to get this sort of system powering my firewall and ADSL modem.

Note: I took these at different exposures to show the detail of the solar panel, wiring, meter displays and laptop screen. The diodes are there to bypass a shaded string. One is not connected because of the string re-wiring.

All photos (c) 2002 Richard Guy Briggs Email Web

Last modified by Richard Guy Briggs on Sat May 11 16:50:33 EDT 2002