@NeverDie My thought was that amorphous silicon (a-Si) cells have better spectral response to artificial light than crystalline cells (c-Si). However, after investigating this a little bit I've found that this doesn't seem to be true. Instead, it's shown everywhere that c-Si cells have better response to every wavelength:
Moreover, when the light source has wide spectrum (like the sun or an incandescent bulb), c-Si panels take the advantage and produce significantly more energy from the same source, and this all explains why a-Si cells are almost two times less effective than c-Si (roughly 8% vs 20%). Please note, because of narrow spectrum a LED lamp will be obviously inefficient for a PV panel.
But at the same time, there are reports of a-Si cells being 4x more effective in low light than crystalline. Indeed, both crystalline and poly-crystalline cells may degrade a lot:
The seem happens due to low parallel resistance of c-Si type cells. Shunt resistance of amorphous cells is naturally higher which results to less degradation of Vmpp and hence higher efficiency in low light conditions. Some paper show the shunt resistance rather low, when other mentions it relatively high, but at extremely low power conditions even 20 kOhm may be too much.
In short, a-Si cells are tend to produce fairly better results in very low light environments. But they can't leverage from wide spectrum sources, yet are subject to the Staebler-Wronski effect when exposed to direct sun (which can be reversed to some extent by heating the panel). In case if the light source is bright enough (around 1000 lx and above) a c-Si pannel should be preferred.
Finally, there are some other kind of solar cells, in particular those made from III-V semiconductors compound and promising even better low light performance.
50pcs/lot EE10-A1 Switching Power Supply High Frequency Transformer 220V to 5-12V Maximum Output 3W
It's the same supplier that I used also and the lot seems to be fine...well at least the 2 pieces that I tested so far .
Now the latching relays. I found them on Aliexpress only and I received something else instead (which seems to happen from time to time) but luckily it works OK so far. So instead of Hongfa relays I got Massuse which seem to be equivalent.
Rest of the components can be sourced from LCSC which is a more trusty component supplier compared to various vendors from Aliexpress (which I already knew..but I didn't had other choices).
Oh and the PCB design and everything else was done using EasyEDA for obvious reasons (JLCPCB is very cheap and pretty good quality for a hobbyist, also their SMT service). I really like their ecosystem - you just create the design using their tool and order everything from there - very, very handy and cheap also as I already mentioned.
Hi @Nca78, I've placed the order on the PCBWay in early January, so it's almost finished. The factory just recently restored assembly services for some kind of boards including this one. Hope to have it in hands within a week or two.
@berkseo Good question. The code seemed good at the time I wrote it, but I can't say that it was extensively tested. I may circle back to it at a future date, and if so, I'll take a closer look. Even with more than 500 downloads of the code, no one has posted any feedback on how well (or not) it has run. Also, I not sure how compatible the posted code is with newer releases of the mysensors library.