Air conditioners on Solar

Air conditioners on Solar and High Initial Current

Air Conditioners and Water Heaters are high wattage appliances. When a compressor of an air conditioner is running it needs high current. Below are some representative wattage based on air conditioner size:

Tonnage	Max Wattage	Max kVA (assuming 0.80 power factor)
1 Ton	1200 Watts or 1.2 kW	1.2 kVA
1.5 Ton	1500 Watts or 1.9 kW	2.4 kVA
2 Ton	2200 Watts or 2.5 kW	3 kVA

For 1 Ton Inverter Base Air Conditionar 2KW solar System is Enough
For 1.5 Ton Inverter Base Air Conditionar 3 KW solar System is Enough
For 2 Ton Inverter Base Air Conditionar 5 KW solar System is Enough
The wattage here is instantaneous power demand or the electricity required when all the components of air conditioner are running. But it varies during the running of an air conditioner because the compressor switches off when the temperature of the room reaches the level set in the thermostat. During the time the compressor is switched off, the electricity consumption is only for a few components in the air conditioner, which is much less. Also the initial starting current is high.

Similarly for electric water heaters the wattage requirement is 2-4 kW or 2000-4000 Watts. The high wattage is required only till the water is heated to a certain temperature.
To handle high loads of air conditioners or water heaters the inverters connected to a solar power generation system should be able to handle high load. So one needs about a 3 to 5 kVA inverter system to handle the same. Most commonly used home inverters are low kVA inverters that cannot handle this load. Also one would also want other appliances in a house to be running and not just the air conditioner, so this increases the overall size of the system.

 

Powering Air Conditioners with Solar: A Complete Guide

Running air conditioners on solar power is one of the most challenging yet rewarding applications of renewable energy. While technically complex, it’s absolutely achievable with proper planning and investment. Here’s what you need to know about keeping cool with the sun’s energy.

The Challenge: Why ACs Are Solar’s Toughest Load

Air conditioners present three unique challenges for solar systems:

1. High Power Consumption: Even efficient units draw 1,000-2,500+ watts continuously.

2. Massive Surge Current: Compressor startups can require 3-6 times running power for 1-3 seconds.

3. Coincident Timing: Peak AC use (afternoon) aligns with peak solar production, but nighttime cooling still requires stored energy.

Understanding Your AC’s Electrical Needs

Key Metrics to Check on Your AC:

• Running Amps/Watts: On the nameplate (e.g., “RLA” = Running Load Amps)

• LRA (Locked Rotor Amps): The absolute maximum startup current (critical for inverter sizing)

• SEER/SEER2 Rating: Higher = more efficient (aim for SEER ≥ 18 for solar applications)

Three Solar Approaches for Air Conditioning

1. Solar-Assisted Grid-Tied (Most Common & Practical)

• How it works: Solar panels feed your main electrical panel, offsetting all home loads including AC.

• System Components: Grid-tied inverter (string or microinverters), solar array, net meter.

• Pros: Simple, cost-effective, uses grid as “battery” at night.

• Cons: No cooling during grid outages.

• Best for: Reducing electricity bills in grid-reliable areas.

2. Hybrid Solar + Battery Backup (Full Independence)

• How it works: Solar charges batteries that power a dedicated “backup loads” panel including AC.

• System Components: Hybrid inverter, battery bank (lithium recommended), solar array, critical loads panel.

• Pros: Works during blackouts, maximizes self-consumption.

• Cons: Expensive ($15k-$30k+ for sufficient capacity), complex installation.

• Best for: Off-grid homes or areas with frequent outages.

3. Direct DC Solar Air Conditioning (Most Efficient but Niche)

• How it works: Specialized DC-powered AC unit runs directly from solar panels through a dedicated controller.

• System Components: DC air conditioner, MPPT controller, solar array, small battery buffer.

• Pros: 20-30% more efficient, simpler wiring, excellent for daytime-only cooling.

• Cons: Limited product availability, higher equipment cost, less flexible.

• Best for: Cabins, offices, or spaces primarily occupied during daylight hours.

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System Sizing Example: Running a 12,000 BTU Mini-Split

Goal: Run a 12,000 BTU, 1,100W mini-split for 6 daytime hours + 2 evening hours via battery.

Step 1: Calculate Energy Needs

• Running wattage: 1,100W

• Daily consumption: 1,100W × 8h = 8,800 Wh = 8.8 kWh

• Add 20% for inverter/battery losses: 10.6 kWh needed daily

Step 2: Solar Array Sizing

• Assume 5 peak sun hours daily

• Solar needed: 10.6 kWh ÷ 5h = 2,120W

• Add 25% margin: 2,650W solar array minimum

• Recommended: 3,000-3,500W (12 x 300W panels)

Step 3: Battery Bank Sizing

• For 2 hours of evening use: 1,100W × 2h = 2.2 kWh

• At 48V system: 2,200Wh ÷ 48V = 46Ah

• Depth of discharge (DoD) safety (80% for lithium): 46Ah ÷ 0.8 = 57.5Ah

• Recommended minimum: 48V 100Ah lithium (5.1 kWh usable)

Step 4: Inverter Sizing

• Running watts: 1,100W

• Startup surge (3× running): 3,300W

• Minimum inverter: 3,500W continuous, 6,500W+ surge

• Recommended: 5,000W hybrid inverter for headroom

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Critical Equipment Recommendations

Air Conditioner Choices (Best to Worst for Solar)

1. Inverter-Driven Mini-Splits (Daikin, Mitsubishi, Gree): Variable-speed compressors = low startup surge, adjustable power draw.

2. Modern High-SEER Central AC (SEER2 ≥ 18): Much more efficient than older units.

3. DC Solar AC Units (Hotspot, SolarCool): Purpose-built but limited support.

4. Standard Window Units: Avoid unless very small (≤ 8,000 BTU) and efficient (EER ≥ 12).

Essential System Components

• Inverter: Must handle LRA surge. Look for “high surge capacity” models (Victron MultiPlus, Schneider XW+, Deye/Sol-Ark).

• Batteries: Lithium Iron Phosphate (LiFePO4) only. Need high continuous discharge (≥ 100A). Size for at least 2-3 hours of runtime.

• Solar Panels: More is better. Consider east-west split arrays for longer production day.

 

 

 

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