Not much done today, and no picture unfortunately for reasons explained below.
I was thinking about the best way to put the three small solar panels on my balcony. There were some options, and I decided to let the panels hang on the outer side of railings. I am not sure if that's 'kosher', as the local landlord seems to complain about things like satellite dishes - we'll see. After all, this is the land of alternative energy, solar panels are everywhere, so why not on my balcony! I had to rush to the shop to get some nuts and bolts, and I got cheese and anchovy as well while I was there.
I wired the three panels in parallel. I am still not sure if that's smart, but I'll see, and rewiring them shouldn't be that complicated if necessary. The problem is that those panels are 9V ones, which is sort of a strange voltage for common SLA accumulators. I have both 6V and 12V ones.
When I finished, and put the panels on the balcony, it was already dark, and raining, thus no pictures today.
The meteo node (powered from solar/goldcap combo) died at 4AM, more or less as I expected. The latest reported voltage was 2.71V, but the values from the DHT22 sensor were obviously wrong, and I think I should stop trusting the values much earlier. Let's declare the minimal acceptable voltage as 2.9V. At this level, the voltage begun to drop quickly, and the humidity reported by DHT22 went to the roof. I assume that the sensor simply went to weeds, and consumed all the power it could get before RF24 module gave up :)
I received the long expected LTC3525 chips today - I'll give them a try tomorrow, and also will try pairing it with that 22F goldcap, and see how long a node will run off it!