Solar Battery Sizing for Iraq Homes (6-12h Backup)

The most common question Iraqi customers ask is: "How big a battery do I need?" The answer is never a single number — it depends on what they want to power, for how long, and whether they have solar panels to recharge during the day. Here is a practical, step-by-step method for sizing solar battery systems for Iraqi homes.

Step 1: List the Loads

Start by listing every appliance the customer wants to run during an outage, along with its running wattage and daily usage hours:

The total daily energy (8.3 kWh in this example) tells you how much the battery needs to supply — but only if there is no solar recharge during the day. With solar, the battery only needs to cover the nighttime portion.

Step 2: Determine Backup Hours

How many hours of grid outage does the customer need to cover? In Iraq, this varies by location:

• Baghdad: 6-10 hours/day, often split into 2-3 blocks
• Basra: 4-8 hours/day
• Mosul: 6-12 hours/day
• Rural areas: 12-24 hours (effectively off-grid)

For a typical Baghdad home, we plan for 8 hours of backup per day. If the customer has solar panels, the battery only needs to cover the evening/nighttime outage (typically 4-6 hours), because daytime outages are covered by solar.

Step 3: Calculate Required Battery Capacity

Using the example above, if we need to cover 8 hours without solar:

Method A: Full load for 8 hours
1391W x 8h = 11,128Wh ≈ 11.1 kWh

Method B: Essential loads only (no AC) for 8 hours
591W x 8h = 4,728Wh ≈ 4.7 kWh

Method C: With solar — battery covers 4 hours of evening outage
1391W x 4h = 5,564Wh ≈ 5.6 kWh (full load)
591W x 4h = 2,364Wh ≈ 2.4 kWh (essential loads)

Step 4: Add the Depth of Discharge Factor

LiFePO₄ batteries can safely discharge to 80-90% of their rated capacity. To get the actual battery size needed, divide by 0.8 (for 80% DoD):

• Method A: 11.1 kWh / 0.8 = 13.9 kWh battery
• Method B: 4.7 kWh / 0.8 = 5.9 kWh battery
• Method C (full): 5.6 kWh / 0.8 = 7.0 kWh battery
• Method C (essential): 2.4 kWh / 0.8 = 3.0 kWh battery

For most Iraqi homes, a 5-10 kWh SH-Home system hits the sweet spot — enough for essential loads during a full-day outage, or full loads during an evening outage with solar recharge.

Step 5: Size the Inverter

The inverter must handle the maximum simultaneous load. In our example, if everything runs at once: 1391W. But we need to account for surges:

• Refrigerator startup: 1000W surge for 2 seconds
• AC startup: 2400W surge for 3 seconds

Peak load including surges: ~3800W. A 3 kW inverter with 2x surge (6 kW) can handle this. But for headroom and future expansion, a 5-6 kW inverter is recommended.

Step 6: Size the Solar Array

If the customer wants solar recharge, the panel array should be sized to replace the daily energy used from the battery:

• Daily energy from battery: ~5-8 kWh
• Iraq peak sun hours: 5.5-6 hours/day
• Required panel capacity: 5-8 kWh / 5.5h / 0.75 (system efficiency) = 1.2-1.9 kWp

So 3-4 panels (450W each) = 1.35-1.8 kWp is sufficient for most homes. For customers who want to run AC on solar during the day, scale up to 6-8 panels (2.7-3.6 kWp).

Real-World Sizing Guide

The most common mistake is oversizing the battery while undersizing the inverter. A 10 kWh battery with a 2 kW inverter cannot run an AC unit — the inverter trips before the battery is even stressed.

Bottom Line

Sizing a solar battery system for an Iraqi home is straightforward: list the loads, determine backup hours, calculate capacity, add DoD factor, then size the inverter and solar array. For most homes, a 5-10 kWh system with a 3-6 kW inverter and 1-3 kWp of solar is the right answer.

Need help sizing a system for a specific customer? Message us on WhatsApp and we will run the numbers.