System 1: 200W Safe Harbor - Johnny Solarseed

What you’ll build

A complete, standalone 200-watt solar system — one panel, one charge controller, one battery, a few DC loads, and nothing else. No permits. No inspections. No electrician. No grid connection. You can build it in an afternoon, and it will quietly generate free electricity for years.

This is the smallest system that’s genuinely useful: enough to run LED lighting, charge phones and laptops, and power a small fan in a shed, garage, or workshop. It’s also the best way to learn how solar works before committing to a bigger build.

What you can power

At 200 watts, you’re generating roughly 600–800 watt-hours per day in Oregon (assuming 3–4 peak sun hours, which is a realistic annual average). That’s enough for:

LED lighting — a few 12V LED panels can light a workspace for hours on a fraction of your daily harvest
Phone and laptop charging — a USB outlet off the battery handles this easily
A small 12V fan — for summer ventilation in a shed or garage
A 12V radio or speaker — background noise while you work

What it won’t do: run power tools, a space heater, a mini-fridge, or anything with a compressor. Those loads need a bigger system. This is about utility lighting and small electronics — and it handles those well.

Shopping list

You can start for under $300 with a lead-acid battery, or ~$500 with LiFePO4. Here’s what you need:

Item	Specs	Approx. Cost
Renogy 200W Monocrystalline Panel	200W, monocrystalline, MC4 connectors	$80–150
Victron SmartSolar MPPT 75/15	MPPT, 12V/24V system, 15A, Bluetooth monitoring	$25–80
LiTime 12V 100Ah LiFePO4	12V deep-cycle, 100Ah, built-in BMS	$80–400
Renogy 30A ANL Fuse Holder	Between charge controller and battery, rated for wire gauge and expected current	$5–10
BougeRV 10AWG PV Extension Cable	10 AWG, MC4 connectors, UV-rated for panel to interior run	$20–40
Renogy Z-bracket mounts (set of 4)	Universal panel mounting, single panel	$15–30
CT CAPETRONIX 12V LED Interior Lights	12V LED lights — your first DC load	$20–60
Total		$245–770

Buy new panels — used panels are fine for larger systems but not worth the hassle at this scale. Stick with name-brand charge controllers (Victron, Renogy, EPEver) because a charge controller is protecting your battery investment, and the difference in cost between reputable and unknown brands is negligible. LiFePO4 is worth the premium over lead-acid for longevity: you’ll get 3,000+ cycles versus 300–500, which means a LiFePO4 battery will likely outlast the panel. LiFePO4 batteries also include a built-in Battery Management System (BMS) that protects against overcharge, over-discharge, and short circuits — an extra layer of safety that lead-acid doesn’t offer.

Wiring topology

This is an all-DC system — no inverter, no AC, no grid connection. That’s what keeps it simple and safe. Here’s the connection sequence:

Panel → MC4 cables → Charge Controller → Fused connection → Battery → DC loads

The panel connects to the charge controller’s solar input via MC4 cables. The charge controller regulates the voltage from the panel and charges the battery safely — without it, the panel would overcharge and damage the battery. From the charge controller’s load output, a fused wire connects to the battery’s positive terminal. DC loads (lights, USB outlets) connect to the battery or the charge controller’s load terminals.

Wire gauge: Use 10–12 AWG for the short DC runs in this system. For the outdoor run from the panel to the interior, use UV-rated PV wire or extension cable with MC4 connectors. Regular household wire isn’t designed for outdoor solar exposure.

Voltage drop matters more at 12V than at higher voltages. The same resistance that loses 1% at 48V loses 4% at 12V. Keep your wire runs short — panel to charge controller should be as direct as possible. If you need a longer run, go with heavier gauge wire (10 AWG or thicker).

A visual wiring diagram is coming soon.

Step-by-step build

Pick your spot. South-facing, minimal shade, on or near your shed or garage. The panel needs direct sun for the longest part of the day. A few hours of morning or evening shade is acceptable — midday shade is not.
Mount the panel. Z-brackets on the roof are the cleanest option. But if you want to start generating power today, lean the panel against the south wall at an angle and mount it properly later. Done beats perfect.
Run wire from panel to interior. Route your MC4 extension cable from the panel through a wall penetration or under a door to where the charge controller will live. Use UV-rated wire for the outdoor portion. Seal any wall penetrations with silicone or a weatherproof gland.
Install the inline fuse. Wire the fuse holder between the charge controller’s battery output and the battery’s positive terminal. This is your critical safety device. Use a fuse rated for your wire gauge and expected maximum current (a 30A fuse is typical for this system).
Connect the battery. Attach the fused positive lead to the battery’s positive terminal, and the negative lead directly from the charge controller to the battery’s negative terminal. The charge controller should power on and display battery voltage. Don’t connect the panel side yet.
Connect the panel to the charge controller. Wire the panel’s MC4 cables to the charge controller’s solar input terminals. If the sun is on the panel, you should immediately see charging current on the display. Battery first, then panel — this is the correct energization sequence.
Connect your DC loads. Wire your 12V LED lights, USB outlets, or whatever you’re powering to the battery or the charge controller’s load terminals. Turn them on. You’re generating electricity.

Safety

This is a small system, but it still stores and moves real energy. Five rules:

Fuse the battery. Always. A short-circuited battery doesn’t care that your system is only 200 watts. The battery can deliver its full discharge current into a fault, and that’s enough to melt wire and start a fire. The inline fuse is the one component that prevents a bad day.
Use listed, certified components. UL-listed panels and reputable charge controllers cost the same as unknown brands and won’t burn your shed down. There’s no savings in uncertified equipment — only risk.
Mount the charge controller indoors, protected from rain, direct sun, and temperature extremes. A covered wall inside the shed or garage is ideal.
UV-rated wire for any exterior runs. Standard wire degrades in sunlight. PV wire and UV-rated cable are designed for this. Don’t shortcut it.
If anything feels wrong — stop. Smells hot, sparks where there shouldn’t be, readings that don’t match expectations — disconnect and figure it out before proceeding. The Johnny Solarseed consult page exists for exactly this. A quick question now is cheaper than a mistake.

Upgrade path

Once you’ve lived with 200 watts for a while, you’ll know exactly what you want more of. That’s the point — this system is a learning platform as much as it is a power source.

The most natural next step is more battery capacity. Your single panel can charge more storage than 100Ah, especially in summer, and more battery means more runtime after dark. Adding a second 100Ah battery in parallel doubles your storage without changing anything else.

After that, you’re looking at System 2: a permitted standalone system with a full panel array, an inverter for AC power, and enough capacity to run real loads. That’s a bigger project with permits and inspections, but by then you’ll understand every component because you’ve already built a working system with your hands. The learning curve is behind you.

The 200W safe harbor is where you start. It’s not where you have to stop.