What Is Load Balancing?
Load balancing in an energy system is the practice of managing how and when electrical loads draw power from available sources like solar panels, battery storage, or the grid, to prevent overloads, optimise self-consumption, and extend battery life.
Think of it as traffic management for electricity. Just as traffic lights prevent gridlock by controlling vehicle flow, load balancing controls which loads run at any given time and from which source they draw power.
Why Load Balancing Matters
Battery Longevity
Preventing deep discharge and overcharge through load control directly extends battery cycle life.
Solar Maximisation
Running heavy loads during peak solar hours means free energy instead of drawing from the battery or grid.
System Protection
Overloading an inverter or battery bank can cause shutdowns, damage, or even fire. Load balancing prevents this.
In a typical household, peak loads (washing machine, oven, kettle) can spike to 5–10kW for short periods. If these spikes happen simultaneously when the battery is low and solar is minimal, the inverter trips. Load balancing prevents coincident peak loads.
Types of Loads
Critical Loads
Must always have power. Never shed these.
- Medical equipment
- Refrigerators & freezers
- Security systems
- Communication equipment
- Core lighting circuits
Deferrable Loads
Can run at any time — schedule for solar peak.
- Washing machine & dryer
- Dishwasher
- EV charging
- Water heater
- Pool / irrigation pumps
Continuous Loads
Run constantly — size storage around these.
- HVAC / air conditioning
- Server & networking equipment
- Standby appliances
- Always-on electronics
Peak / Spike Loads
High inrush current — need inverter headroom.
- Electric ovens & kettles
- Air compressors
- Large power tools
- Motor start-up loads
Load Balancing Strategies
Priority-Based Load Management
Assign every load a priority. When battery state-of-charge (SoC) drops below a threshold, the inverter's energy management system (EMS) sheds loads in reverse priority order.
Priority 1 — Critical
Never shed. Always powered regardless of SoC. (Medical, refrigeration, communication)
Priority 2 — High
Shed below 20% SoC. (Core lighting, entertainment, phone charging)
Priority 3 — Medium
Shed below 40% SoC. (HVAC, water heater)
Priority 4 — Low
Only run when solar is producing surplus. (EV charging, pool pump, washing machine)
Time-of-Use (ToU) Scheduling
Programme deferrable loads to run during specific time windows when solar production is highest (typically 10am–3pm). Most modern hybrid inverters allow timed output circuits or smart socket integration.
Phase Balancing (3-Phase Systems)
In three-phase commercial and industrial systems, unequal load distribution across phases causes neutral current, voltage imbalances, and inefficiency. Distribute single-phase loads evenly across L1, L2, and L3.
Load Balancing in Solar + Battery Systems
In a solar + battery system, the goal is to maximise direct use of solar energy, minimise battery cycling, and never exceed inverter capacity. Here's a recommended daily energy flow:
Dawn (6–9am): Battery powers critical loads. Solar starting to produce but output low. Deferrable loads off.
Morning peak (9am–12pm): Solar output rising. Begin running deferrable loads (washing machine, dishwasher). Battery charging from surplus.
Solar peak (12–3pm): Maximum solar generation. Run highest-wattage loads (EV charging, pool pump). Battery at or near full.
Afternoon (3–6pm): Solar declining. Shift loads back to battery. Avoid starting new high-wattage loads.
Evening (6pm–midnight): Battery discharge. Critical and high-priority loads only. Deferrable loads off.
Night (midnight–6am): Minimal consumption. Only critical loads. Battery resting at low SoC ready for dawn.
Common Load Balancing Mistakes
Undersizing the inverter
Running loads near the inverter's continuous rating leaves no headroom for motor start-up spikes. Size your inverter at 125% of your expected peak load.
No load audit first
Designing a balancing strategy without measuring actual consumption leads to poor priorities and wrong SoC thresholds.
Treating all loads equally
Not all 1kW loads are equal, a resistive heater and an induction motor both draw 1kW but have very different system impacts.
Ignoring standby power
Standby loads (TVs, routers, chargers) can collectively draw 200–500W continuously. Audit these and switch off where possible.
Over-discharging the battery
Allowing the battery to reach 0% SoC regularly dramatically reduces cycle life. Set a low SoC cutoff at 10–20% as a buffer.
No monitoring in place
Without real-time monitoring of SoC, solar production, and load draw, you're flying blind. Install a battery monitor and data logger.