# LAB-004: 600W Solar Array Deployment Guide

> Issue #529 | Cabin Compute Lab Power System
> Budget: $200-500

## System Overview

4x 150W panels → MPPT controller → 12V battery bank → 1000W inverter → 120V AC

```
[PANELS 4x150W]  ──series/parallel──►  [MPPT 30A]  ──►  [BATTERY BANK 4x12V]
                                                                  │
                                                           [1000W INVERTER]
                                                                  │
                                                        [120V AC OUTLETS]
```

## Wiring Configuration

**Panels:** 2S2P (two in series, two strings in parallel)
- Series pair: 18V + 18V = 36V at 8.3A
- Parallel strings: 36V at 16.6A total
- Total: ~600W at 36V DC

**Battery bank:** 4x 12V in parallel
- Voltage: 12V (stays 12V)
- Capacity: sum of all 4 batteries (e.g., 4x 100Ah = 400Ah)
- Usable: ~200Ah (50% depth of discharge for longevity)

## Parts List

| Item | Spec | Est. Cost |
|------|------|-----------|
| MPPT Charge Controller | 30A minimum, 12V/24V, 100V input | $60-100 |
| Pure Sine Wave Inverter | 1000W continuous, 12V input | $80-120 |
| MC4 Connectors | 4 pairs (Y-connectors for parallel) | $15-20 |
| 10AWG PV Wire | 50ft (panels to controller) | $25-35 |
| 6AWG Battery Wire | 10ft (bank to inverter) | $15-20 |
| Inline Fuse | 30A between controller and batteries | $10 |
| Fuse/Breaker | 100A between batteries and inverter | $15-20 |
| Battery Cables | 4/0 AWG, 1ft jumpers for parallel | $20-30 |
| Extension Cord | 12-gauge, 50ft (inverter to desk) | $20-30 |
| Kill-A-Watt Meter | Verify clean AC output | $25 |
| **Total** | | **$285-405** |

## Wiring Diagram

```
                    ┌──────────────────────────────┐
                    │         SOLAR PANELS          │
                    │   ┌──────┐      ┌──────┐     │
                    │   │ 150W │──+──│ 150W │     │  String 1 (36V)
                    │   └──────┘  │   └──────┘     │
                    │             │                  │
                    │   ┌──────┐  │   ┌──────┐     │
                    │   │ 150W │──+──│ 150W │     │  String 2 (36V)
                    │   └──────┘      └──────┘     │
                    └──────────┬───────────────────┘
                               │ PV+ PV-
                               │ 10AWG
                    ┌──────────▼───────────────────┐
                    │      MPPT CONTROLLER          │
                    │      30A, 12V/24V              │
                    │  PV INPUT ──── BATTERY OUTPUT  │
                    └──────────┬───────────────────┘
                               │ BAT+ BAT-
                               │ 6AWG + 30A fuse
                    ┌──────────▼───────────────────┐
                    │       BATTERY BANK             │
                    │  ┌──────┐ ┌──────┐            │
                    │  │ 12V  │═│ 12V  │  (parallel)│
                    │  └──────┘ └──────┘            │
                    │  ┌──────┐ ┌──────┐            │
                    │  │ 12V  │═│ 12V  │  (parallel)│
                    │  └──────┘ └──────┘            │
                    └──────────┬───────────────────┘
                               │ 4/0 AWG + 100A breaker
                    ┌──────────▼───────────────────┐
                    │    1000W INVERTER              │
                    │  12V DC ──── 120V AC           │
                    └──────────┬───────────────────┘
                               │ 12-gauge extension
                    ┌──────────▼───────────────────┐
                    │     AC OUTLETS                 │
                    │  Desk │ Coffee Table │ Spare  │
                    └──────────────────────────────┘
```

## Installation Checklist

### Pre-Installation
- [ ] Verify panel specs (Voc, Isc, Vmp, Imp) match wiring plan
- [ ] Test each panel individually with multimeter (should read ~18V open circuit)
- [ ] Verify battery bank voltage (12.4V+ for charged batteries)
- [ ] Clear panel mounting area of snow/shade/debris

### Wiring Order (safety: work from panels down)
1. [ ] Mount panels or secure in optimal sun position (south-facing, 30-45° tilt)
2. [ ] Connect panel strings in series (+ to -) with MC4 connectors
3. [ ] Connect string outputs in parallel with Y-connectors (PV+ and PV-)
4. [ ] Run 10AWG PV wire from panels to controller location
5. [ ] Connect PV wires to MPPT controller PV input
6. [ ] Connect battery bank to controller battery output (with 30A fuse)
7. [ ] Connect inverter to battery bank (with 100A breaker)
8. [ ] Run 12-gauge extension cord from inverter to desk zone

### Battery Bank Wiring
- [ ] Wire 4 batteries in parallel: all + together, all - together
- [ ] Use 4/0 AWG cables for jumpers (short as possible)
- [ ] Connect load/controller to diagonally opposite terminals (balances charge/discharge)
- [ ] Torque all connections to spec

### Testing
- [ ] Verify controller shows PV input voltage (should be ~36V in sun)
- [ ] Verify controller shows battery charging current
- [ ] Verify inverter powers on without load
- [ ] Test with single laptop first
- [ ] Monitor for 1 hour: check for hot connections, smells, unusual sounds
- [ ] Run Kill-A-Watt on inverter output to verify clean 120V AC
- [ ] 48-hour stability test: leave system running under normal load

### Documentation
- [ ] Photo of wiring diagram on site
- [ ] Photo of installed panels
- [ ] Photo of battery bank and connections
- [ ] Photo of controller display showing charge status
- [ ] Upload all photos to issue #529

## Safety Notes

1. **Always disconnect panels before working on wiring** — panels produce voltage in any light
2. **Fuse everything** — 30A between controller and batteries, 100A between batteries and inverter
3. **Vent batteries** — if using lead-acid, ensure adequate ventilation for hydrogen gas
4. **Check polarity twice** — reverse polarity WILL damage controller and inverter
5. **Secure all connections** — loose connections cause arcing and fire
6. **Keep batteries off concrete** — use plywood or plastic battery tray
7. **No Bitcoin miners on base load** — explicitly out of scope

## Estimated Runtime

With 600W panels and 400Ah battery bank at 50% DoD:
- 200Ah × 12V = 2,400Wh usable
- Laptop + monitor + accessories: ~100W
- **Runtime on batteries alone: ~24 hours**
- With daytime solar charging: essentially unlimited during sun hours
- Cloudy days: expect 4-6 hours of reduced charging

---

*Generated for issue #529 | LAB-004*