S9 hashing on direct DC solar and AC PSU hybrid system
Here I have an S9 powdered both by the 12v DC output of a solar charge mppt controller and the output of an apw3++ plugged into an inverter. The output of the solar charge controller is wired directly to DC output lugs of the PSU. As the clouds roll by the output of the solar power decreases and the PSU delivers more power from the inverter. This same technique can be used by plugging the PSU into a grid powered outlet instead of the inverter. It's basically a way to subsidize the power consumption of a miner with solar power directly. It's pretty cool to watch.
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Clever! So you are OR-ing DC sources at the PSU lugs. Have you measured backfeed into MPPT when PSU is at full load? Would love to replicate this in Nigeria where grid is backup, not primary. What MPPT + panel wattage are you using for one S9?
I'm not sure what OR-ing is. I haven't measured any back feeding to the charge controller, not sure how I would do that, I don't have very much measurement equipment. The charge controller is 60amps which is good for one hashboard. The array of panels is a string of 4 adding up to about 1300w.
Thanks for specs! 60A + 1300W string makes sense for 1 hashboard. OR-ing just means 2 DC sources into 1 load. For Nigeria where we have 1800W+ sun, I could run 2-3 hashboards that way. Will try with a blocking diode to protect MPPT. Appreciate!
Direct DC solar is better in energy saving.
I'm looking forward to trying out some of the newer hashboards that run on 24v instead of 12v.
Clever setup wiring the MPPT 12V output directly to the APW3++ DC bus lugs so the AC PSU only makes up the delta when solar sags.
One thing worth watching on the APW3++ when paralleling with an external MPPT on the 12V rails: if the MPPT float/absorption voltage creeps slightly above the APW3++ setpoint (usually ~12.15V–12.35V) during a sudden cloud-edge spike, check that your MPPT has reverse-current protection or a low-drop ideal diode (MOSFET OR-ing controller) on the positive rail, though the APW3++ output synchronous rectifiers usually tolerate mild backfeed. What voltage setpoint are you running on the MPPT vs the PSU so solar takes priority under full sun?