Discharge + solar cycling

Solar Calc

Pack voltage, solar cycling, and skid charge — C-rates, extra Wh to refill, and whether each day recovers.

System voltage

1 skid paralleled · 1S1P → 12 V 100 Ah on the bus

Amp-hours add when skid banks parallel onto this bus. Chemistry, SOC and LVD stay system-level.

Day load

Night load

Day is sunrise–sunset at the map pin. Night is the rest. Set night to 0 for a daytime-only skid. Both at 0 uses the sum of DC circuit watts as a 24/7 load.

Chemistry

Flat voltage, low sag, ~100% usable. Bulk 0.2C recommended, 0.05–0.5C window, charge factor ×1.03. Capacity 0.3%/°C vs 25 °C, no bulk below 0 °C.

Starting SOC100%

Low battery cutoff20% SOC

Load sheds at this SOC and will not discharge further. LFP typically 10–20%. Lead-acid typically 50%.

System efficiency100%

Charge controller

MPPT ~96% into the bus. PWM delivers ~Isc × battery voltage. Set each skid's battery-side current cap on the solar skid cards.

Wiring + connector loss3%

Day air

°C

Night air

°C

Pack temperature lags air by ~6 h. Cold cuts capacity and raises IR; LFP/NMC will not bulk charge below 0 °C.

Charge target100% SOC

Genset / DC-DC backupStarts at the start SOC (at or above LVD), charges until stop SOC or the daily hour cap.

Solar array

Pin the site, then add parallel skids. Observed cloud uses the last 30 days at this pin.

33.869° S, 151.209° E

From

Match From / To to a logger or HMI export. Window is 7 days, capped at 93 d.

Replay Open-Meteo for this rangeDaily mean cloud and recorded Tmin / Tmax at this pin for the dates you set. Sit harvest and min SOC next to the unit's kWh / SOC log. Archive lags ~8 days.

Facing0° N

Install angle34°

0° is flat. Equator-facing at ~latitude is a solid starting point. All skids share this facing and tilt.

Solar skids

Each skid has its own array, MPPT and battery bank. Banks parallel onto one DC bus — voltages must match.

1 skid · 200 W STC combined · 21.6 V max Voc · 12.2 A Isc sum · 1S1P 12 V 100 Ah

Name

Battery voltage

In series

In parallel

Ah per battery

1S1P · 1 × 12 V 100 Ah → 12 V 100 Ah pack

This skid's bank parallels onto the 12 V DC bus. Parallel multiplies amp-hours; series stacks to the bus.

Panel open-circuit voltage

Voc

Panel short-circuit current

Isc

Panel wattage

Number of panels

Panel configuration

MPPT battery-side current

Leave blank for no current cap on this skid.

1S2P · 21.6 V Voc · 12.2 A Isc · 200 W STC

Use specified solar yieldReplaces cloud cover. Daily kWh is spread over daylight using the sun arc at this site.

Solar yield

kWh/d

Last 30 days cloud at this pinDaily mean cloud and recorded min/max air from Open-Meteo. Beam is scaled each day; each day uses that day's Tmax / Tmin. Sets the cycle window to 30 days.

Seasonal analysis at this pinFive-year Open-Meteo mean cloud and air for each season, applied to a 14-day cycle at mid-season sun. Independent of last-30-days and specified yield. Does not change day / night air on the form.

Cloud cover

Cloudy block is centered on solar noon. Overcast hours drop beam and keep ~22% diffuse.

Dust film0%

Accumulation0.0%/d

Mine trailers typically 10–20% film. 0.3–1%/day between washes. Specified yield already includes soiling.

Cycling timespan

Custom span

Cable CSA

One-way length (m) and copper CSA (mm²) for each run. Leave CSA on Auto to size it, or pick the cable on the skid to check drop and ampacity.

Solar array

Length

CSA

16 mm² · 0.42 V (2.4%) · rating 85 A

Drop allowance3%

Battery bus

Length

CSA

6 mm² · 0.26 V (2.1%) · rating 46 A

Bus drop allowance3%

DC circuits

Each load off the main battery bus. If day and night load are 0, these watts are the system load.

No branch circuits yet — add lights, radio, instruments, or the 400 W payload.

Terminal voltage

Unassisted discharge — no solar, start SOC to low-battery cutoff

LiFePO44S nominal 12.8 VCutoff 20% · 12.98 V

Sun arc

Solar elevation for the selected date. Shaded region is the cloudy block.

Daylight 11.2 h · sunrise 06:24 · sunset 17:36 · peak sun 46° · harvest 1.04 kWh/d · first cutoff 2026-08-28 02:24 · LVD 20% · pack 12–29 °C

Cloud used

Cloud preset applied each day of the window, with the day / night air you set.

Daily window

Harvest versus load for each calendar day in From – To. Sit this next to a logger kWh / SOC export from the unit.

Battery cycling

SOC over 7 days with load and PV. Amber fill is array power.

20–100% SOCCutoff 2026-08-28 02:24

Array does not restore the bank to the charge target before sunset on every day in the window.

Charge & skid

Restore energy includes load during sun, charge factor, controller, and wiring.

1/7 days recover

Nameplate 1.28 kWh · usable to LVD 1.02 kWh · no-sun autonomy 17h 4m · PSH 5.19 h · sun needed 7.90 h · charge factor ×1.03 · clip 0 Wh/d

LiFePO4 charge C-rate

peak 0.07 C · 7.04 A

min 0.05Crec 0.20Cmax 0.50C

Above min CUnder recommended bulkWithin max C

Pack lags air ~6 h. LiFePO4 absorb 13.85 V at mean bank temperature.

Day	Dawn	Dusk	Min	Recovered	Charge
D1	69%	94%	65%	held	34.5 Ah
D2	34%	61%	30%	short	35.6 Ah
D3	20%	50%	20%	short	36.0 Ah
D4	20%	51%	20%	short	36.3 Ah
D5	20%	51%	20%	short	36.5 Ah
D6	20%	51%	20%	short	36.8 Ah
D7	20%	52%	20%	short	37.0 Ah

Cable CSA

Length and CSA you set, then drop and ampacity. Auto sizes to the allowance; pick a size to check the cable on the skid.

Solar array

Auto

15.3 A · min 16 mm² · auto

Battery bus

Auto

20.8 A · min 6 mm² · auto

Circuit voltage

Sun or backup on: charger is the PSU — DC bus sits above the battery posts. After dark: battery is the supply — posts sit above the bus and each downstream circuit by I×R. LVD opens the load disconnect: posts stay at pack voltage, bus and circuits go to 0 V until charge lifts SOC off the floor.

LVD — load bus 0 V

Add DC circuits in Cable CSA to plot far-end voltage on each run.

Discharge points

60 W day · 60 W night · 13.53 V start · 12.98 V end

SOC	Time	Voltage
100%	0 min	13.53 V
75%	17h 17m	12.98 V
50%	17h 17m	12.98 V
25%	17h 17m	12.98 V
20%	17h 17m	12.98 V

Clear-sky POA from sun position at the map pin, panel tilt/azimuth, and Meinel air mass. Cloud is a noon-centered overcast block, a From–To Open-Meteo replay, the last 30 days at the pin, or a 5-year seasonal mean. Parallel skids share the bus and sum onto it. Estimate only — not a substitute for a site survey or manufacturer I–V data.