Made a temporary “solar combiner box” to parallel PV array in various series configurations. This is for trial purposes only. Made 2 conductors of #2 CU wire that branch off into 4 conductors each of #10 4703 of appropriate length. Same gender MC4 connectors are attached to the ends of each of the four #10. Have tried 2, 3, and 4 panels in series. Now trying 6 panels; 3 strings of 2 in series. Voltage drop on a 43′ run from the panels to my charge controller is less than 0.7V @ 25A~45-50V (while loaded).
Will likely revert to panels in series of 3; 3 strings per array per charge controller. I’m still learning to not over-manage or micromanage the system. Other than ensuring loads aren’t excessive during dusk to dawn and watering batteries every few months, most things seem to reach a point of homeostasis, not requiring intervention.
A few things I’ve learned or noticed:
If you don’t use it, you lose it. I’m amazed how rapidly a small but continuous load will drain the battery bank (462Ah / 24v) when not being replenished. All my loads except my freezer and an occasional light, are generally off at dusk.
I’ve become very energy conscious. This isn’t power from the local power company; this is MY power. I’m not a normally possessive person… It’s now impossible for me to leave a room without making sure I’m not wasting energy. Frivolous use a energy is a thing of the past.
My 3000w PSW inverter uses ~ 75 watts to just be “on”, and ~9 watts to be kept in standby where is scans for loads over 40 watts. For this reason, I’m considering getting a another much smaller PSW inverter of about 300w just for nighttime use. Seems shameful to be using 75 watts to provide power for a freezer that uses only 79 watts, even if only when compressor is working a few times an evening.
TIP: Adding thermal mass to the freezer such as milk or soda containers full of water to displace air space will actually decrease “short-cycling” of compressor which is inherently inefficient. The goal is to minimize air space in freezer. This is especially true of vertical freezers that dump the cold air onto the floor when opened. But, I’ve also noticed an improvement in my chest freezer too, and the temps stay more consistent. An added benefit is less frost buildup since less air is moving into or out of the compartment with each opening of the door.
Another thing was my washing machine would get stuck between cycles while only the timer was on. I can leave the inverter out of standby to run washer, run it with another useful concurrent load, or wire a larger bulb into the washer’s “ON” indicator circuit (seems wasteful).
What I initially thought was a high self-discharge rate throughout the night was nothing more than the batteries cooling to ambient temps. My batteries would be floating at 27v up to nightfall. Then, in the morning, they would drop to 25.9 or even 25.8v. This was merely a drop (from 29C daytime to 23C nighttime) of the bank temp revealing itself. Obviously, keeping battery bank as consistently ~25C or so is optimal, but not possible in 90-100F temps.
Loads via kill-a-watt:
8 ft3 chest freezer, 127w to start, 79w to run
RULE 2000 32v water pump, 64w
Imac 27-inch computer 110-220w, variability based on display brightness!
wireless router 11w
5000btu window ac, 530w when very hot, 490w when has caught up and comfortable.
Hot plate, 1320w, but duty cycle decreases to ~40-50% once up to temp (boiling).
Craftsman cordless drill charger, 45w
1000w microwave, about 1700w for a fraction of a second, then 1130w.
Craftsman “6.5 HP” shop vacuum, 1410 watts
SpeedQueen coinop washer, 460 during agitation, 430-580 when spinning. This reading is because this washer begins to simultaneously pump out and spin with the tub full of water. Thus, the initial load is high, but then decreases as water is pumped out and the RPM of the tub increases.
Notes: Inverter default setting of 110v was changed to 120v. Have not noticed any increase in operational temps of any devices used on inverter vs. household current, nor have I encountered any that I couldn’t use due to poor power quality. Measured under various loads, V=119.xx to 120.xx, Hz=59.xx to 60.xx using Meanwell TS3000 inverter.
Post time: Jan-06-2017