Solar powered lights

IKEA "sunnan"

I alreay use the IKEA "sunnan" for a few years, this led-lamp has a detachable base consisting of a solar panel and three internal AA batteries. This is a convenient lamp if you are camping, or for some bedtime reading.

Official information: "Recharging time is 9-12 hours in sunlight, but over 12 hours on a cloudy day. When the battery is fully charged, the product will light at full power for aprox. 3 hours. Includes 3 rechargeable batteries (AA 1.2V) that stores energy from the sun."

I connected a simple bicycle light (rated 0.6W, 6V) to the solar panel, and measured 0.098 A at 5.13 V. This was on a perfect sunny day at midday. This panel measures 7.5 cm by 7.5 cm and produces 0.50 W peak.

Brennenstuhl "SOL 80"

Then ran into a solar led lamp of a slightly bigger format:

I had to call the gas-emergency line (where gas refers to: gear acquisition syndrome) but luckily I got clearance to spend the money so I could take it home ... and take it apart. :-)

This is IP44 rated which means (first '4':) "Protected against solids objects over 1mm (e.g. tools, wires and small wires)" and (second '4':) "Protected against sprays from all directions - limited ingress permitted". See ip_ratings for more info.

Interestingly, the internal battery has a 'Pb' (Lead) marking on it, where one whould expect a NiMH battery perhaps? Also the rating on the battery itself is 6.0V / 3.2Ah (at 20HR), where according to the sticker on the exterior it has only: 6.0V / 2.0Ah.

Comparison

First of all, the Brennenstuhl appears to use amorphous silicon for its solar panel, which is cheaper and less efficient than monocrystalline or polycrystalline silicon solar cells. This is compensated by its mere size, in comparison to the IKEA unit:

After some soldering I was able to get these values:

IKEA Sunnan Panel size	Charging	Light
56.25 cm^2	0.50W	0.63W
Brennenstuhl Panel size	Charging	Light	Sensor / standby
273.0 cm^2	0.93W	1.95W	0.015W

Although the largest panel has actually 4.85 times the surface area, the peak power produced is not even double that of the smaller panel.

In this image you can see the difference between the light from the 80 LED's and the much smaller IKEA lamp:

Future ideas

I was hoping to do some proper home projects with solar power using this panel, but I think the size has deceived me (!) .. at only 1W peak power it's not going to be feasible to make this into a solar powered server, or solar powered webcam, etcetera. However what might be feasible is to replace the white LEDs with IR LEDs and use this as an aid to my security cams.