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Greater than 80% discharged.,

As to the BMS overvoltage, the inverter response lag only has to last long enough to trip overvoltage trigger, with any filtering on it, whatever that may be for a given BMS. In addition to filtering, raising the trip voltage is most assured way to prevent too many false triggers which would...

Nothing to do with backside shading.

Depends on your north/south latitude. Earth has an axis tilt of about 23.5 degrees so winter axis tilts away from sun with lower maximum sun angle above horizon (with shorter daylight hours), summer it tilts toward the sun and sun rises higher in sky at noon (with longer daylight hours). If...

If it is really 0.36 milliohms near 25 degs C that is pretty poor for 280AH cell. If you have a current shunt in 0.1 to 0.5 milliohm range you can check your meter accuracy. (shunt mV divided by current rating = shunt resistance, 75mV/500 amp = 0.150 milliohms) Always check on battery...

A relatively low priced unit that does AC input load shaving is Conext SW series inverter/chargers.

Buying self contained bundled cells with internal BMS does nothing for relieving balancing requirement.

I think the price of Maxwell Ultracaps has skyrocketed since Musk/Tesla bought them out. It might be due to their getting new business direction and not making caps for general market so all there is left is what is in the existing inventory pipeline. I have tried a few of the Chinese...

The time should be more than long enough for pass-through relay to release when AC input is removed. Before you go to extra trouble check the features in inverter first. Some have the ability to setup user parameters to do what you want to do without any external added grid relay disconnect...

At 13.2v with four series cells, assuming all cells balanced, would be 50% state of charge. You will not get any balancing on most BMS's though. Boost (absorb) to 14.2v will get you some balancing.

Both MPPT and PWM SCC will be limited by their attached battery voltage level for absorb and float voltage set on SCC's.. Bulk charge current will be sum of output from both controllers. There are many variants on how a SCC exits absorb level charging mode. One may exit absorb voltage before...

There are flywheel momentum powered units for UPS. Usually used to allow time for a backup generator to get online. To keep synchronous AC phase switchover requires DC to AC inverter. Bypass directly to generator can be done when inverter slowly slews it voltage/freq/phase to match...

Cell self-leakage discharge is not captured by battery monitor Columb counter. Expect 0.5 to 2% of cell capacity per month depending on ambient temp and cell aging condition. This adds to monitor representation inaccuracy, unless Columb counter reset to 100% by a full charge periodically...

It is not uncommon for cell balance to diverge when run at high discharge current or over their total capacity range. Cell mismatch will cause this. Most folks think same AH capacity and same cell impedance means matched cells. Matching also requires same terminal voltage drop difference for...

One other thing. You should always fully charge battery after adding water to mix up electrolyte.

Check you do not have too much voltage drop on interconnect/cabling between inverter and batteries with charging bulk current.

I would guess you have max cell charge limit set too low. What is the BMS model?

As long as pretty well matched and facing same direction it is okay. If two strings are different voltage rating the series group with lower voltage will just suck down and dissipate current from higher voltage series string due to their inherent forward biased internal diodes associated with...

I used to solder my 2/0 lugs on. I used Excelene welding cable as the insulation can take the heat.

It highly depends on how panels are configured. When you have a lot of shading issues it is usually better to run more parallel configurations than serial configurations. You can sub-divide panel groups and run multiple PV controllers to get better yield.

R_dc = rho * length / Area length in meters, cross section area in meters^2 Metal rho Silver 1.5860E-08 ohm-m Copper 1.6780E-08 ohm-m Gold 2.2400E-08 ohm-m Aluminum 2.6548E-08 ohm-m Nickel 6.8400E-08 ohm-m Brass 8.1000E-08 ohm-m Tin 1.1000E-07 ohm-m Stranded wire gets...

Looks like 3 x12 cell panel = 36 cells. Expect about 23v Voc and 18v Vmp per panel. A bit lower after they warm up in sunlight. Find out from spec sheet or count how many series cells there are per panel. The number of series cells in a panel determines its Voc and Vmp voltages. The size of...

Without knowing the current put through the cells not much can be determined. You need to check single series string of cells at a time. For 280AH cells you should check with a cell current of between 56 amps and 100 amps. I usually charge each cell to a little over 50% state of charge at...

Track at least your air conditioner power consumption during summer months between 2-8 pm. That is the big consumer. If I recall, Az doesn't do daylight savings time so 8 pm is close to sunset. Your consumption by far is likely air conditioning between 2-8 pm in summer, unless you are...

Maximum Voc has little to do with illumination shortcomings. As long as there is enough illumination to overcome panel self-leakage shunt current the panel will go to Voc.

That is a very good deal (if not damaged). 107 lbs is about right for 5 kVA isolation transformer. A new unit like that one would be about $1000 at current pricing, Likely have to ship truck freight that will cost twice the price of unit.

CT transformers have accuracy and tolerance in their reported current and its phase relative to AC voltage (need phase info to know if current is going in or out AC input port). A safety margin is usually held by inverter when no-selling is selected that prevent supplementing AC input for AC...