What is the best order to upgrade a van electrical system?

Start with the battery — it's the anchor component everything else is sized around. Then add solar and an MPPT controller. Then a DC-DC charger for alternator charging. Then battery monitoring. Then an inverter if you need 120V. Shore power last, if at all. Each step provides real benefit on its own; later steps build on the foundation.

Should I upgrade the battery or solar first?

Battery first. A better battery that you can't fully charge is still better than a worse battery — you're running more usable capacity. But more importantly, upgrading to LiFePO4 changes your charging requirements (you'll need an MPPT controller and ideally a DC-DC charger that can handle LiFePO4 charge profiles). Do the battery, then immediately add the right charging equipment.

Van Electrical Upgrades: The Right Order to Do Them

Whether you're upgrading an older build or improving a factory RV electrical system, order matters. Each upgrade should build on the previous one and provide immediate benefit on its own.

Starting from a factory RV or used conversion

Many people inherit a van or RV with a basic electrical system — AGM battery, basic converter, maybe a generator. The upgrade sequence:

Step 1: Battery upgrade (LiFePO4)

Replace AGM with LiFePO4 of equivalent or greater capacity. Immediate benefits:

2× usable capacity at same voltage
Faster charging
No maintenance
Accurate state-of-charge via voltage (LiFePO4 has flatter discharge curve)

What you also need: Ensure your shore charger has a LiFePO4 profile, or add a Victron Blue Smart IP22 charger at the same time.

Step 2: MPPT solar controller (if solar exists)

If the factory system has PWM solar, replace with MPPT. A 20–30A MPPT typically extracts 20–30% more energy from the same panels. Simple swap with big gains.

If no solar: add 200–300W panels + MPPT controller together.

Step 3: DC-DC charger for alternator

Add a 20–30A DC-DC charger between the starter battery and house battery. Delivers 240–360W of charging while driving. On a 4-hour drive, this adds 60–90Ah to the house battery. For weekend campers, this single upgrade often eliminates the need for shore power.

Step 4: Battery monitor

Add a shunt-based battery monitor (Victron SmartShunt or similar). Now you know your actual state of charge — not a guess from voltage. Essential for LiFePO4 which shows a flat voltage curve until near depletion.

Step 5: Inverter (if needed)

Add a 1,000–2,000W pure sine wave inverter for 120V loads. Size for your actual AC loads — see what size inverter do I need?.

Step 6: Shore power (optional)

If you stay at campgrounds regularly, add a 30A shore power inlet and a proper converter/charger (or upgrade to an inverter/charger). Worth it for full-timers; optional for weekend users.

Starting from scratch

If you're building from a bare cargo van:

Plan first — calculate your loads, size the system, draw a wiring diagram (see how to plan a van electrical system)
Buy battery — the anchor component; everything else is sized around it
Install bus bars, main fuse, and fuse block — the electrical backbone before any loads
Wire the battery monitor shunt — on the negative side, before adding any loads
Add solar + MPPT — your primary charging source
Add DC-DC charger — your driving charging source
Wire 12V loads — fridge, lighting, fans, USB hubs
Add inverter — once 12V system is working correctly
Add shore power — last, and only if needed

Common upgrade mistakes to avoid

Don't add solar without upgrading the controller: Adding panels to a PWM controller wastes most of the gain.

Don't upgrade the battery without updating the charger: An AGM converter will charge LiFePO4 incorrectly — may work but shortens battery life.

Don't wire the inverter through the bus bar: The inverter needs its own direct cable from the battery with its own large fuse. Running inverter current through the bus bar risks overloading the bus bar and its wiring.