RV Power Designer

1 — Getting Started NEW

When you open RV Power Designer for the first time, the Setup Guide walks you through five quick questions to configure your system correctly from the start. You can relaunch it any time using the 🧭 Setup Guide button in the settings bar.

The 5-Step Setup Guide

1. Rig type — van, caravan, motorhome, or boat. Informs the voltage recommendation.
2. Camping style — weekends, extended touring, off-grid boondocking, or full-time living. Sets autonomy days.
3. Key loads — tick everything you plan to run (fridge, aircon, laptop, TV, Starlink, microwave). Multi-select, optional.
4. Travel region — sets peak sun hours. Six regions covering Australia, NZ, USA, and Europe.
5. Review & apply — shows recommended voltage, battery type, autonomy, and sun hours. Click Apply & Start.

Recommended Workflow

1. Run the Setup Guide or set voltage and battery type manually in the Settings Bar.
2. Load a Quick Template or add your own appliances in the Loads tab.
3. Review Sizing Results — battery Ah, solar W, inverter VA, recharge time, SoC.
4. Check System Checks & Compatibility alerts at the top of the Sizing tab for wiring or voltage issues.
5. Open the Wiring tab and enter cable run lengths to get ABYC-compliant wire sizes.
6. Use 🔨 Build System to auto-select components, then review the Shopping List.
7. Save your design, or Share it via URL.

2 — System Settings Bar

The dark navy bar below the tabs is always visible. It contains the four core settings plus action buttons.

Which voltage should I choose?

3 — Quick Templates

Click ⚡ Quick Templates in the Loads tab toolbar to open a grid of 10 pre-built RV setups. Each loads all appliances and configures voltage, battery type, autonomy, and sun hours automatically.

4 — Adding Appliances

The Loads tab is where you build your appliance list. Each appliance has Name, Watts, and Hours/day. The type (AC or DC) determines how the load is calculated.

AC vs DC loads

Input validation

Appliance entries are validated as you type. Watts must be a positive number — negative values and zero are blocked with an inline warning. Hours must be between 0 and 24. Entries above 5,000W are allowed but flagged with a caution, since that figure is likely a surge rating rather than a running wattage.

💡 AC low-wattage inverter hint

If you set an appliance to type AC with watts under 100W, a yellow hint appears below the row: “Under 100W via inverter. If this has a 12V DC adapter, set type to DC for a more accurate figure.”

This matters because inverters are significantly less efficient at very low loads — a 30W CPAP running through a 2000W inverter may draw 50–60W from the battery once inverter overhead is included. The same CPAP with a native 12V DC adapter draws close to 30W. Setting the type to DC gives a more accurate battery sizing result. The hint clears automatically if you switch the type to DC or raise the wattage above 100W.

Advanced preferences

Expand Advanced Preferences below the appliance table to set roof space, solar/inverter efficiency, and charge source contributions (alternator, shore power, generator).

4b — Appliance Reference Lookup NEW

The app has two ways to use the appliance reference library: browse and add from the panel, or let the name field look it up for you as you type.

Browse panel

Click 📋 Browse Appliances in the Loads tab toolbar to open the full reference library. It contains 42 common RV appliances across seven categories: Lighting, Fridges, Kitchen, Climate, Tech, Medical, and Water. Each entry shows typical wattage, daily hours, and a note on the figure.

1. Click 📋 Browse Appliances to open the panel.
2. Type in the search box to filter by name or category.
3. Click + Add on any row to add it to your appliance list.
4. Adjust watts or hours after adding to match your specific gear.

💡 Name field live lookup

When you add a new appliance and start typing a name, the app matches your input against the reference library as you type. After three characters it searches for the best match and, if found, automatically fills the watts and hours fields.

5 — Location & Seasonal Sun Hours NEW

Peak sun hours (PSH) is the single biggest variable in solar sizing. The location picker provides annual average, summer, and winter values for 25+ locations.

Using the picker

1. Select your region from the Location / Sun Hours dropdown in the Loads tab.
2. The annual average PSH is applied to the Peak Sun Hours field automatically.
3. A panel shows summer and winter values with a plain-language seasonal note.
4. An orange warning appears if winter solar is more than 40% below the annual average.

6 — Understanding Sizing Results

The Sizing tab shows every calculated result with full detail. All values update live.

Core formulas

Key results explained

7 — 30-Day Weather Simulation NEW

The 30-Day Weather Simulation runs your designed system against real historical solar radiation data and shows day-by-day how your battery state-of-charge would have held up. It lives at the bottom of the Sizing tab.

How to use it

Select any named location in the Loads tab first — the simulation requires coordinates to fetch data, so the "custom" entry keeps it locked. Once a named location is selected, open the Sizing tab and scroll to the simulation card. Choose your starting SoC and derate factor, then click ▶ Run Simulation. The app fetches the last 30 days of actual shortwave radiation from the Open-Meteo free historical archive and runs the simulation immediately.

Options

Understanding the output

Verdict banners

The chart

The canvas line chart shows battery SoC % across all 30 days. The line colour changes by zone — blue above 50%, amber between 20–50%, red below 20%. Background colour bands mark the same zones. Red dots highlight individual critical days. An expandable daily breakdown table below the chart shows every day's PSH, Wh produced, Wh consumed, net Wh, and closing SoC.

How it compares to other tools

Most competing tools use a randomly generated 7-day weather model — clicking "generate new weather" produces a different answer each time, which limits its usefulness for real planning. This simulation uses 30 days of actual recorded shortwave radiation data from the Open-Meteo historical archive for your specific location. The result is more trustworthy and grounded in real conditions rather than a synthetic model.

8 — System Checks & Compatibility NEW

At the top of the Sizing tab, look for the ⚡ System Checks & Compatibility label. The app automatically runs these checks on every recalculation and displays any issues directly below the label.

9 — ABYC Wire Sizing Calculator NEW

At the top of the Wiring tab, this calculator sizes each cable segment to ABYC E-11 standard — the specification used by marine and professional RV electricians. It accounts for both ampacity and voltage drop.

How to use it

1. Add your appliances so the calculator knows the amps for each circuit.
2. Open the Wiring tab.
3. Tick applicable derating conditions (bundled, hot area, continuous load).
4. Enter the one-way run length for each segment in feet or metres.
5. Recommended AWG, constraining factor, and fuse size appear immediately.

Derating conditions

Reading the results

• Ampacity AWG — minimum to carry the current without overheating
• VDrop AWG — minimum to keep voltage loss within target
• Use AWG ✓ — the larger of the two (labelled VD↑ or A↑ to show which limits)
• Fuse — next standard ANL/MIDI size above 125% of load amps (ABYC E-11)

10 — Solar Generator Finder NEW

The 🔋 Solar Generator tab answers the question most people ask before committing to a DIY build: "Should I just buy a solar generator instead?" It uses your actual load profile to give a data-driven answer and compare both paths.

How it works

1. Add your appliances in the Loads tab so the tool knows your daily Wh requirement and peak AC load.
2. Open the 🔋 Solar Generator tab.
3. A recommendation banner appears immediately: solar generator is a good fit, you're in the crossover zone, or DIY wins.
4. Scroll down for ranked product cards and the side-by-side comparison table.

The recommendation thresholds

Scoring and ranking

Each product is scored against your specific load on four factors: capacity fit vs your daily Wh × autonomy days, inverter power vs your peak AC load, solar input vs your required array size, and value (Wh per dollar). The best match is highlighted and shown first.

Products covered

DIY vs Solar Generator comparison table

The comparison table at the bottom of the tab is generated live from your sizing. It compares the best-matched generator against your DIY build estimate on upfront cost, capacity, setup time, portability, repairability, expandability, inverter power, lifespan, and best use case. Green highlights indicate the winner on each row.

11 — Component Selector & Shopping List UPDATED

Regional pricing

Product prices and buy links are region-aware. Use the 🛒 Shop selector in the Settings Bar to switch between AU, US, UK, CA, and EU. The currency label in the bar updates to match (AUD, USD, GBP, CAD, EUR). All prices are approximate retail estimates — verify with the retailer before purchasing.

The Components tab lets you build a complete shopping list by selecting from built-in products or adding your own. Battery, Solar Panels, and Inverter categories support multi-select — you can choose multiple products in each. All other categories (Charge Controller, DC-DC, Monitor, ATS) remain single-select.

Selection modes by category

🔍 Product quick search

When you click + Add Custom [Category], a quick search field appears at the top of the form for Battery, Charge Controller, Inverter, DC-DC Charger, and Battery Monitor categories. Type a brand or model name and matching products appear immediately — click one to add it directly to your component list without filling in the manual form.

Quantity stepper

When you select a Battery, Solar Panel, or Inverter card, a − qty + stepper appears on the card. For batteries and panels, the quantity is floored at the calculated minimum from your sizing results — you can increase it but not go below what the system needs. For inverters, quantity is free-set.

Dual (or multiple) inverter setups

Select both inverter cards — for example a 1,200W and a 3,000W unit. Both appear in the shopping list as separate line items. A blue notice automatically appears showing the combined continuous wattage and reminding you that each inverter needs its own dedicated battery cabling, appropriately sized fusing, and a transfer switch or manual changeover to select between them.

Mixing battery types or panel sizes

You can select, for example, two different battery models to build a mixed bank. The shopping list calculates line totals for each. However, mixing battery chemistries or capacities in a single bank is not recommended without specific BMS support — always consult a qualified installer if doing this.

Shopping list

The Shopping List at the bottom of the Components tab updates live. It shows Component, Product, Qty, Unit Price, Line Total, and a Buy link for each selected item. A running total appears at the bottom, with an ancillaries estimate (~$350 for fuses, bus bars, wiring, connectors, mounting hardware). Prices from custom products are included if you enter them as $xxx.

Adding custom products

Click + Add Custom [Category] to open the add form. Enter the product name, spec, price, and a URL from any retailer. Custom products appear as selectable cards in the same grid, marked with a purple "Custom" badge, and can be deleted with the ✕ button.

12 — Build System — Auto-Suggest

Click 🔨 Build System to automatically select best-matched components based on your sizing. The modal shows reasoning flags, component recommendations with quantities, and an estimated cost range including ancillaries and installation.

13 — Wiring Guide & System Diagram UPDATED

The Wiring tab includes the ABYC calculator (section 8), a nine-step Installation Sequence with component-specific values, and Safety Rules.

The Diagram tab shows a live schematic that changes based on system voltage:

Component-aware diagram

When you select products in the Components tab, the diagram updates to reflect your actual choices rather than just calculated values:

14 — Saving, Exporting & Sharing

15 — Accuracy & Limitations

What the calculations do well

• Internally consistent — every formula is tested against known values (103 unit tests)
• Industry-standard rule-of-thumb sizing used by professional installers
• Conservative buffers (20% battery, 25% solar) provide real-world margin
• ABYC E-11 wire sizing is the correct professional standard for marine/RV DC systems

Limitations to be aware of

• Temperature derating — cold reduces LiFePO4 capacity; heat reduces panel output. Not modelled.
• Panel Voc check — uses estimated values. Always verify against your exact panel datasheet.
• Surge currents — motor loads draw 2–5× running current at startup. Inverter surge estimate is a guide only.
• Parallel battery strings — the calculator sizes a single bank. Parallel strings have additional balancing considerations.
• AC wiring — all 240V/120V AC wiring must be performed by a licensed electrician. The app sizes AC loads but does not size AC cables.
• Wire run lengths — the ABYC calculator needs accurate run lengths. Underestimating produces undersized cable recommendations.

16 — FAQ

Why is my recommended battery so large?

Check your autonomy setting. 3-day autonomy triples the battery requirement compared to 1-day. Also verify that appliance hours/day are realistic rather than worst-case.

The ABYC calculator recommends a very large wire. Is that right?

Likely yes. Voltage drop is the limiting factor on long runs at low voltage — a 12V system with a 10-metre inverter cable needs very heavy wire to keep VDrop under 1%. Check that you've only ticked derating conditions that actually apply to your installation.

My solar array is bigger than my roof can fit. What do I do?

Switch to higher-wattage panels (400W instead of 200W), reduce loads, add alternator or shore charging to supplement solar, or accept that you'll need shore power or a generator on high-load days.

When should I use 24V or 48V instead of 12V?

Upgrade to 24V when solar exceeds 600W or battery bank exceeds 400Ah at 12V. Upgrade to 48V when daily load exceeds 4,000Wh or you need a large inverter-charger. The app flags both in Build System warnings and Compatibility alerts.

What does VD↑ mean in the wire sizing table?

The wire size is limited by voltage drop, not ampacity. The wire can carry the current safely, but a smaller size would cause unacceptable voltage loss over the run length. Common on long runs at low voltage (12V).

Why does the Compatibility check show a Voc warning for my 48V system?

On a 48V system, four 400W panels in series gives ~160V Voc — which exceeds most 150V-rated MPPT controllers. Use a higher-rated controller (200V+ input) or adjust your panel string configuration to stay within limits.

Can I run air conditioning on solar?

Yes, but it requires a large system: typically 48V, 300–400Ah+ LiFePO4, and 2,000W+ solar. At 12V the cable requirements become impractical. The Build System will flag this automatically.

Can I select two inverters — like a 1,200W and a 3,000W?

Yes. In the Inverter category, click both cards to select them. The shopping list shows them as separate line items with a combined wattage note. The intended use case is two inverters on separate circuits — a small, efficient inverter for everyday loads (fridge, laptop, lights) and a large inverter that you switch on for high-demand appliances like air conditioning or a microwave. This avoids running a 3,000W inverter at 5% load all day, which is inefficient and stresses the unit. Each inverter needs its own battery cable, inline fuse within 45cm of the battery, and either a manual changeover switch or separate AC circuits.

Can I select two different battery models?

Yes — select as many battery cards as you like. The shopping list totals them separately. In practice, mixing different battery models in a single bank is only advisable if they share the same chemistry, voltage, and ideally the same capacity. Mismatched batteries can cause uneven charging and premature failure. The safer approach is to use multiples of one model (e.g. 3× 100Ah LiFePO4) rather than mixing sizes.