The Beginner Guide To Charge A Battery From Solar Panels

So you've entered into the world of outdoor living, you've gotten all the gear but you have absolutely no idea what to do with it? Don't get caught out being labelled the dreaded term "ATGANI" (all the gear and no idea)! In this article we will go through the beginners guide in charging your off-grid battery directly from your solar panel or solar blanket.

Whether you’re camping deep in the bush, living off-grid, or just prepping for blackouts, this guide will walk you through how to get the most out of your solar setup — without all the technical waffle.

Solar Blankets

Lithium Batteries

Why Choose Solar for Charging Batteries?

Unlike traditional generators that guzzle fuel and rattle your peace, solar panels are completely silent and they don’t spit out fumes. With solar, you're left with clean, renewable energy.

Once your system’s set up, the sun does all the work. No pulling cords, no petrol stops, no maintenance drama.

Top benefits of Going Solar:

• No ongoing fuel costs

• Works anywhere there’s sun, even with limited sunlight.

• No noise, fumes, or moving parts

• Great for off-grid caravans, utes, 4WDs, sheds, and tiny homes

What Gear Do You Need To Charge Your Battery With Solar?

To charge a battery using solar, you’ll need four key components:

1. Solar Panel or Solar Blanket – collects energy from the sun

2. Solar Charge Controller – regulates how power flows into your battery

3. Battery – stores the energy for later use

4. Wiring – connects the system safely

Let’s break that down 👇

1. Solar Panel or Solar Blanket:

The panel’s job is to soak up sunlight and convert it into electricity. For 12V or 24V batteries, you’ll typically use panels in the 100W–400W range. For 36V or 48V batteries you may prefer a panel or blanket with a 400W+ capacity.

Check out this free solar panel calculator by battery stuff to work out your needs based on your equipment.

Flexible solar blankets or rigid framed solar panels both do the trick.

Solar Blanket

Solar Panel

2. Solar Charge Controller

Don’t skip this bit. A charge controller protects your battery from overcharging and regulates current flow. Without a solar charge controller, you're risking your batteries health and diminishing its life cycle.

Two types:

• PWM (Pulse Width Modulation) – basic, but less efficient. Whilst cheaper in price than their MPPT counterpart, they are less effective in cold weather and low-light conditions

• MPPT (Maximum Power Point Tracking) – more efficient, pulls more power in low light and colder weather. Excess voltage will also be converted into usable current which means none of your power will be wasted. MPPT chargers are more expensive than PWM, however we believe the benefits far outweigh the extra cost.

Check out this helpful guide by Morningstar to learn more about the differences between PWM and MPPT solar charge controllers.

3. Battery

This is where the solar power is stored. Lithium batteries are the top pick for off-grid setups as they’re lightweight, fast-charging, and can be discharged deeper than old-school AGM or lead-acid.

The general rule of thumb we use when choosing a battery is a 1:1.5-2 ratio for battery capacity to solar capacity.

For instance if you chose a 100Ah battery, you would look to use it with a 150-200W solar panel or blanket. For that reason, the iTech 12V 160x Pro 160Ah Lithium Battery is a perfect match for the iTech 300W Solar Blanket.

4. Wiring

You’ll need the following:

• Fuses or circuit breakers 
• Solar and battery cables
• Anderson plugs/MC4 connectors

Let's go into each of those in more details.

Fuses or circuit breakers:

Used primarily for safety against surges, most MPPTs come with an internal fuse but it's still recommended to use an external fuse as well. You will need a different fuse for your solar and your battery. (these should be connected within 15cm of the battery and solar panel/blanket, but refer to the fuse specifications for more information). 

Our suggested fuse sizes are as follows:

• Solar Fuse: 1.25x panel's max current (e.g. 10A panel = 12.5A fuse)
• Battery Fuse: Equal or slightly above controller's max charge current (e.g. 40A controller = 50A fuse)

For more information on fuse amp allocation, please refer to your solar panel and battery user manuals, or check out the following article.

Solar Fuse

Battery Fuse

A photo example of a solar fuse and battery fuse.

Solar and battery cables:

These should be rated for your output - Don’t skimp on cable size! voltage drop is a killer over long distances.

A photo of a 5m Bluetti solar cable with MC4 connectors at each end.

Anderson plugs or MC4 connectors:

These may be attached to your cables already

How To Connect Your Solar Panel To Your Battery

Alright, now we're ready to rock! Just for a quick recap, you should have the following:

• ✅ Solar panel (with MC4 connectors)

• ✅ MPPT solar charge controller

• ✅ Lithium battery (12V / 24V / 48V depending on your system)

• ✅ Solar fuse (in-line, sized for your panel output)

• ✅ Battery fuse (in-line, sized for your charge controller output)

• ✅ Solar cable with MC4 connectors

• ✅ Battery cable with Anderson plugs

Here’s the steps involved with connecting your solar to your battery:

1. Set up your battery

2. Wire the battery to the charge controller

3. Connect the solar panel (but don't plug it in yet!)

4. Plug in the solar panel

5. Test the system

Let's explore each one of those steps in more detail.

🔋 Step 1: Set Up Your Battery

Why first? Your charge controller needs to detect the battery voltage before it can safely regulate solar input.

✅ What to do:

• Connect your battery cables with Anderson plugs to the battery terminals (red to +, black to -).

• Add your battery fuse (e.g. 40A or 60A depending on your system) on the positive battery cable, as close to the battery terminal as possible.

💡 Tip: Make sure your battery is partially charged so the controller reads the voltage properly when you power it up.

⚙️ Step 2: Wire the Battery to the Charge Controller

Now connect the battery to the charge controller’s battery terminals (usually labelled “BATT” or has a battery icon).

✅ What to do:

• Connect positive Anderson cable from the battery fuse to the positive terminal on the controller.

• Connect negative Anderson cable directly from the battery to the controller’s negative terminal.

⚠️ Important: Double-check polarity — reverse polarity can damage your controller or battery!

☀️ Step 3: Connect the Solar Panel (but don’t plug it in yet!)

Now get your solar cables with MC4 connectors and attach your solar fuse to the positive cable.

✅ What to do:

• Connect positive MC4 lead from the panel to solar fuse.

• Connect fused lead to charge controller’s positive PV input.

• Connect negative MC4 lead directly to controller’s PV negative terminal.

❗ Don't plug in the solar panel to the MC4 connectors just yet. This ensures the system isn’t live while you're still wiring.

🔌 Step 4: Plug in the Solar Panel

Now everything's safe and in place, plug in the MC4 connectors from the solar panel into your fused solar cable.

This will allow power to start flowing into the charge controller — and you'll usually see lights or a digital display activate.

🧪 Step 5: Test the System

Check the charge controller display or LED indicators:

• ✅ Confirm it's detecting both battery voltage and solar input

• ✅ Monitor the charging status (usually shows amps going into the battery)

• ✅ Make sure your fuses aren't blowing — if they are, double-check your wiring and fuse size

That’s it! Power should start flowing immediately. 

Get The Most Out Of Your Off-Grid Solar System:

Keep Panels Clean

Dust, bird poop, and shadows can dramatically reduce performance. Wipe them down regularly, and tilt them toward the sun if possible.

Monitor Your Battery

Overcharging and deep discharges will shorten battery life. If your battery has Bluetooth or a monitor, keep an eye on voltage and state of charge (SOC).

Size Your System Right

Some rough daily consumption estimates:

You’d want at least a 200Ah lithium battery and 300–400W of solar to comfortably keep this up. Please also note that if you wish to convert power from DC to AC you will need an inverter.