Don't know where I read someone with similar cfg, but for those who are interested, here is my experimental cfg.
Solar panel 12V 40W ( more than 10 years old, not optimal orientation = real only 30W ).
Jally, undervolted from 1,02V to 0,95, stock clock & software, hashing @ 5 Gh/s (0,2% error rate
) (sometimes, cause the low voltage, it stasts @ 4,2 / 4,3, expecially when powered by stock PSU when there is not sun. In this case power cycling is useful to regain 5 Gh/s ). It draws little more than 2A @ 12V, efficiency little better than 5W/Ghs.
No battery and power regulator. Panel and original psu are coupled by a series of shottky diodes (I loose near a watt here). When the sun shines, voltages from panel is higher so it has the priority ( in this case voltage in main power line of the jally goes near 14V ) , when there is no sun, PSU kicks in keeping voltage near 12,5V.
PRO. All solar production in adsorbed by the system so no battery is required (mainenatance free). Good battery has 90% efficiency so all this is a another good gain. Jally runs smoother when panel is active, probably cause higher input voltage and infinite better voltage stability ( stock PSU is really really bad..........ssshhh, I should not tell this cause it is not exploded yet
).
CON. When Jally is in idle (current drops from 2A to near 1A), there are no voltage regulation, so voltages soar to 16V, wich is not really good because if I remember well caps are 12V rated. All other electronics should run fine.
When there is no sun, I loose near a watt on the diodes, and when there is sun the PSU loose near 2 watt in idle.
Coming soon a more powerful hashing system with similar philosophy. I'm looking at something like this http://www.mini-box.com/DCDC-USB-200?sc=8&category=981 cause the voltage programmable capability and ultra wide input voltage ( every little watt from solar will be saved )
Solar panel 12V 40W ( more than 10 years old, not optimal orientation = real only 30W ).
Jally, undervolted from 1,02V to 0,95, stock clock & software, hashing @ 5 Gh/s (0,2% error rate
) (sometimes, cause the low voltage, it stasts @ 4,2 / 4,3, expecially when powered by stock PSU when there is not sun. In this case power cycling is useful to regain 5 Gh/s ). It draws little more than 2A @ 12V, efficiency little better than 5W/Ghs. No battery and power regulator. Panel and original psu are coupled by a series of shottky diodes (I loose near a watt here). When the sun shines, voltages from panel is higher so it has the priority ( in this case voltage in main power line of the jally goes near 14V ) , when there is no sun, PSU kicks in keeping voltage near 12,5V.
PRO. All solar production in adsorbed by the system so no battery is required (mainenatance free). Good battery has 90% efficiency so all this is a another good gain. Jally runs smoother when panel is active, probably cause higher input voltage and infinite better voltage stability ( stock PSU is really really bad..........ssshhh, I should not tell this cause it is not exploded yet
).CON. When Jally is in idle (current drops from 2A to near 1A), there are no voltage regulation, so voltages soar to 16V, wich is not really good because if I remember well caps are 12V rated. All other electronics should run fine.
When there is no sun, I loose near a watt on the diodes, and when there is sun the PSU loose near 2 watt in idle.
Coming soon a more powerful hashing system with similar philosophy. I'm looking at something like this http://www.mini-box.com/DCDC-USB-200?sc=8&category=981 cause the voltage programmable capability and ultra wide input voltage ( every little watt from solar will be saved
)