Bluetti AC300 vs AC500 — Whole-Home Backup Explained for UK Power Cuts
⚡ Bluetti AC300 vs AC500: Which Whole-Home Backup System Fits Your UK Home?
If you’re looking beyond small portable units and want expandable backup power for longer outages, Bluetti’s modular systems are the next step.
This guide compares the Bluetti AC300 and Bluetti AC500 in plain English — what they’re for, how they scale, and how to choose confidently for UK power cuts.
🔍 Quick Comparison
| Feature | Bluetti AC300 | Bluetti AC500 |
|---|---|---|
| Power class | High-power modular home backup | Whole-home class modular backup |
| Who it’s for | Home essentials plus longer runtimes | Higher demand homes and bigger loads |
| Expandability | Modular battery system | Modular battery system |
| Best use cases | Fridge, lights, Wi-Fi, home working, extended outages | Higher load backup, larger homes, multi-appliance setups |
Important: both systems are modular inverter units and require compatible expansion batteries to run. Always check the exact battery compatibility on the product pages.
🏗️ What “Modular” Actually Means
With modular Bluetti systems, you’re not buying a single sealed box. You’re building a backup setup with two main parts:
- Inverter module — the “brains” that delivers AC power to your devices
- Expansion batteries — the stored energy that determines your runtime
This is why AC300 and AC500 can be such strong long-term choices: you can start with a sensible setup and expand later if your needs grow.
🔋 Expansion Planning: How AC300 & AC500 Grow With You
One of the biggest advantages of Bluetti’s modular systems is that you don’t need to buy your “final” setup on day one. Both AC300 and AC500 are designed to grow with your household.
🔌 Start with what you need now
Most UK households begin by covering essentials during outages:
- Fridge and freezer
- Wi-Fi and communications
- Lighting and charging devices
- Home working equipment
A base inverter with a suitable amount of battery capacity can comfortably handle these needs without overspending.
➕ Expand later if your needs increase
If your requirements grow over time — longer outages, more appliances, or seasonal energy use — additional expansion batteries can be added later.
- No need to replace your inverter
- No need to redesign your setup
- Battery capacity scales as your needs change
This approach helps avoid buying too much upfront while keeping your system future-ready.
🏠 AC300 vs AC500: expansion mindset
- AC300 — ideal when you want strong essentials backup with room to grow over time
- AC500 — better suited if you expect higher loads or want to build toward a more whole-home capable system
Expansion planning isn’t about maximising capacity immediately — it’s about choosing a system that won’t limit you later.
🔋 Bluetti AC300 — Modular Home Backup (High-Power)
The Bluetti AC300 inverter module is designed for households that want serious backup capability without jumping straight to the largest system.
✅ Best for
- Keeping essential rooms powered during longer outages
- Running higher-draw home essentials more comfortably
- Home working setups that need stable power
- Upgrading later by adding more battery capacity
⚠️ What to know
- It is a modular system and requires compatible expansion batteries to operate
- Ideal when you want more than “small backup”, but don’t need maximum whole-home demand
Best choice if: you want a scalable home backup system that covers essentials with room to expand.
🏠 Bluetti AC500 — Whole-Home Class Backup (Higher Demand)
The Bluetti AC500 inverter module is built for higher-demand households aiming for a more whole-home style setup.
✅ Best for
- Higher load backup where multiple appliances may run together
- Larger homes or households with bigger power needs
- Longer outages where expandable capacity matters
- Building a more future-proof backup setup
⚠️ What to know
- It is a modular system and requires compatible expansion batteries to operate
- Choose this when your home backup needs go beyond “essentials only”
Best choice if: you want a higher-demand system and the flexibility to build toward whole-home backup.
✅ Which One Should You Choose?
Choose AC300 if:
- You want robust home essentials backup and longer runtimes
- You prefer a strong modular starting point with upgrade headroom
- Your goal is reliable backup without oversizing
Choose AC500 if:
- Your home has higher power demand or multiple appliances to support
- You want to build toward a more whole-home capable system
- You want maximum flexibility for future expansion
🧮 Work Out What You Actually Need
Before you choose AC300 or AC500, get clear on your household loads. This prevents overspending and ensures your backup setup matches reality.
Use the Backup Power Calculator to estimate what you want to run and your ideal runtime.
🌧️ UK Power Cut Readiness Tip
For UK winter storms and outages, the best strategy is usually:
- Identify your must-run essentials
- Choose an inverter system that comfortably handles those loads
- Size battery capacity for the outage duration you want to cover
For a broader preparedness plan, see our guide: UK Storm & Power Cut Preparedness Guide
🔋 Final Thoughts
Bluetti AC300 and AC500 are both powerful modular options — the right choice depends on how much your home needs to run at once and how far you want to expand.
If you want a confident “next step up” from smaller power stations, start with AC300. If you’re building toward higher demand and more whole-home capability, AC500 is the stronger foundation.