Weekender van 400W 12V
12V system, designed for a -10C (14F) cold snap - saved 2026-08-16
Compatibility checks
infoArray is oversized for the controller - output will clip at ~384WArray size vs controller charge output
The array can push 31.3A but the controller tops out at 30A. This is common and usually fine: you harvest more in mornings, evenings, and winter, and the controller simply caps peak output. Verify the controller's max array wattage is not exceeded (separate check).
Array = 200W x 2 panels = 400W Potential charge current = 400W / 12.8V = 31.3A Controller rated charge current: 30A
11 passing checks - expand to see the math
passBattery matches the 12V systemSystem voltage coherence
LiTime 12V 230Ah Plus LiFePO4 (12.8V nominal) is a 12V-class battery.
battery nominal 12.8V is in the 12V class == system 12V
passInverter matches the 12V systemSystem voltage coherence
Renogy 1000W 12V Pure Sine Wave Inverter (RNG-INVT-1000-12V-P2) DC input is 12V-class.
inverter DC input 12V is in the 12V class == system 12V
passCharge controller supports 12V banksSystem voltage coherence
Victron Energy SmartSolar MPPT 100/30 supports 12/24V battery banks.
controller battery voltages [12, 24] include 12V
passString Voc stays at 47.9V at -10C - cannot reach the 100V limit at any temperatureCold-temperature string voltage
2 x Rich Solar MEGA 200 200W 12V Monocrystalline Solar Panel in series stays below the Victron Energy SmartSolar MPPT 100/30 max PV input voltage at your design low temperature. This string cannot reach 100V at any physically possible temperature.
Why this matters: Panel voltage rises as temperature falls. A string that measures fine in summer can exceed the controller's absolute maximum input voltage on the first cold clear morning, which can permanently destroy the controller - and at these DC power levels, failures can start fires. This is the mistake experienced builders catch most often in DIY parts lists.
Voc_string = Voc x N_series x (1 + tempCoeff/100 x (T_design - 25))
= 21.80V x 2 x (1 + (-0.28%/100) x (-10 - 25))
= 21.80V x 2 x 1.0980 = 47.9V
Controller max PV input: 100V
Crossover: string Voc reaches 100V at T = 25 + (100/43.6 - 1) x 100/-0.28 = -437C (below absolute zero - never reached)passString Vmp 36.8V has healthy margin over the 12V bankMPPT voltage margin
Clears the start floor cold and the hot-weather floor with sag included.
Vmp_string = 18.40V x 2 = 36.8V Start floor = V_batt + 5V = 12 + 5 = 17V Hot Vmp (~11% sag) = 36.8V x 0.89 = 32.8V vs hot floor 20V
passArray short-circuit current 11.60A is within the 35A limitArray current vs controller input limit
Within the Victron Energy SmartSolar MPPT 100/30 published max PV short-circuit current.
Isc_array = 11.60A x 1 parallel = 11.60A Controller max PV short-circuit current: 35A = 35A (manufacturer-specified, compared directly)
passArray 400W is within the controller's 440W rating at 12VMax array wattage for battery voltage
Within the published maximum array wattage.
Array = 200W x 2 panels = 400W Controller max array wattage at 12V: 440W
passVictron Energy SmartSolar MPPT 100/30 supports LiFePO4 chargingBattery chemistry support
Controller has a lithium profile or user-adjustable charge voltages.
battery chemistry = lifepo4; controller lifepo4_profile = true
passBank BMS limit 200A comfortably covers the inverter's 78.1A drawInverter draw vs battery BMS limit
Healthy headroom at full inverter load.
Inverter draw = 1000W / 12.8V = 78.1A Bank BMS limit = 200A x 1 batteries = 200A Headroom band starts at 80% of limit = 160A
passBank BMS peak 600A covers the inverter's 156.3A surgeInverter surge vs battery peak limit
Surge loads within the bank's published peak rating.
Surge draw = 2000W / 12.8V = 156.3A Bank BMS peak = 600A x 1 batteries = 600A
passCharge current 30A is within the bank's 200A capacityCharge current vs bank capacity
Charge rate within limits.
Controller rated charge = 30A Bank max charge = manufacturer max charge 200A x 1 = 200A
Parts list
| Part | Qty | Est. price | Where to buy |
|---|---|---|---|
Rich Solar MEGA 200 200W 12V Monocrystalline Solar Panel | 2 | $340 | |
Victron Energy SmartSolar MPPT 100/30 controllerdatasheet | 1 | $220 | |
LiTime 12V 230Ah Plus LiFePO4 batterydatasheet | 1 | $520 | |
Renogy 1000W 12V Pure Sine Wave Inverter (RNG-INVT-1000-12V-P2) inverterdatasheet | 1 | $175.99 | |
| Estimated total | $1,255.99 |
Wire and fuse guidance
| Segment | Continuous | Run (one way) | Copper wire | V-drop | Fuse/breaker |
|---|---|---|---|---|---|
| Array to charge controller | 11.6A | 15 ft | 14 AWG | 2.39% | 15APV-rated (gPV) fuse or DC breaker |
| Charge controller to battery bank | 30.0A | 5 ft | 8 AWG | 1.47% | 40AClass T |
| Battery bank to inverter | 78.1A | 3 ft | 3 AWG | 0.72% | 100AClass T |
Array to charge controller: show the math
Continuous current = 11.6A Design current = 11.6A x 1.25 (NEC continuous) = 14.5A Wire: 14 AWG copper (75C ampacity 20A); voltage drop 2.39% over 30ft round trip at 36.8V (target <= 3%) Fuse/breaker: 15A - two criteria, both required: carry the load: fuse >= design 14.5A -> next standard size = 15A protect the wire: fuse 15A <= 14 AWG ampacity 20A - OK construction: PV-rated (gPV) fuse or DC breaker
Charge controller to battery bank: show the math
Continuous current = 30A Design current = 30A x 1.25 (NEC continuous) = 37.5A Wire: 8 AWG copper (75C ampacity 50A); voltage drop 1.47% over 10ft round trip at 12.8V (target <= 3%) Fuse/breaker: 40A - two criteria, both required: carry the load: fuse >= design 37.5A -> next standard size = 40A protect the wire: fuse 40A <= 8 AWG ampacity 50A - OK bank BMS continuous 200A >= fuse 40A: the bank can hold the fuse's rated load construction: Class T (interrupt rating matters on battery mains)
Battery bank to inverter: show the math
Continuous current = 78.1A Design current = 78.1A x 1.25 (NEC continuous) = 97.7A Wire: 3 AWG copper (75C ampacity 100A); voltage drop 0.72% over 6ft round trip at 12.8V (target <= 3%) Fuse/breaker: 100A - two criteria, both required: carry the load: fuse >= design 97.7A -> next standard size = 100A protect the wire: fuse 100A <= 3 AWG ampacity 100A - OK bank BMS continuous 200A >= fuse 100A: the bank can hold the fuse's rated load construction: Class T (interrupt rating matters on battery mains)
Mount the fuse close to the battery positive terminal - it protects the wire run, so the unprotected stub should be as short as possible.
Sized for 75C copper ampacity with the NEC 1.25 continuous factor and a 3% voltage-drop target. Round up when between sizes and verify against local code.
Balance of system - shopping list
| Item | Qty | For |
|---|---|---|
| 14 AWG copper wire | 1 | ~35 ft total (15 ft one way, round trip + slack) - Array to charge controller |
| 15A PV-rated (gPV) fuse or DC breaker | 1 | Array to charge controller |
| 8 AWG copper wire | 1 | ~15 ft total (5 ft one way, round trip + slack) - Charge controller to battery bank |
| 40A Class T | 1 | Charge controller to battery bank - include the matching fuse holder/block |
| 3 AWG copper wire | 1 | ~10 ft total (3 ft one way, round trip + slack) - Battery bank to inverter |
| 100A Class T | 1 | Battery bank to inverter - include the matching fuse holder/block |
Derived from the wire and fuse guidance above. Wire lengths include round trip plus slack - verify against your actual layout, and verify ratings against local code. Buy fuses and wire from reputable electrical suppliers; marketplace listings for these items are a common source of counterfeit or mislabeled parts.
About this build
This build is for van owners who travel occasionally rather than live on the road - weekend warriors, ski trippers, and overlanders who spend a few nights out at a time. The goal is reliable power for phone charging, LED lighting, a compressor fridge, and a laptop without the weight, cost, or complexity of a full-time system. 12V is the natural choice: the loads are small, the wire runs are short, and staying on the van's native voltage keeps the whole system simple.
LiFePO4 wins over AGM here even for occasional use - it is far lighter, lasts many more cycles, and you can use most of its rated capacity instead of babying it above half charge. The 1000W inverter class covers laptop chargers and small kitchen gadgets; it will not run a microwave or induction burner, and that is the deliberate trade that keeps this build cheap and light. The two panels wire in series so the array stays well within the controller's voltage window while keeping current low for thin roof-run wiring.
Common questions
Should I go 12V or 24V for a weekender van?
Stick with 12V for occasional use. The component ecosystem is bigger, everything speaks the van's native voltage, and at these modest loads you never hit the current levels where 24V starts paying off.
Can I add more solar later?
Some - but the charge controller and battery set the ceiling. If you expect to move toward full-time use, size the controller up front and plan the battery bank for expansion instead of maxing out a small controller on day one. Clone this build in the builder and swap parts to see what the checks say.
Is lithium worth it for a few weekends a month?
Yes. LiFePO4 gives you more usable capacity per pound and per dollar over its life, holds charge well between trips, and tolerates deep discharge. AGM still works, but you pay for it in weight and in capacity you should not use.