How to Choose an Inverter, Battery, and Solar Panels for Home Backup During Blackouts

Frequent blackouts and power outages make autonomous home power systems more relevant than ever. A reliable backup setup usually includes a solar inverter, LiFePO₄ batteries, and solar panels. This guide explains how to correctly size your inverter, battery bank, and PV array so your home can operate smoothly during prolonged outages.

Step 1. Calculate the required load: which appliances must work during a blackout

First, define which devices must stay powered and how long they will operate.

• Circulation pump for solid-fuel boiler — 85 W × 12 h = 1.02 kWh
• Refrigerator — 100 W × 8 h = 0.8 kWh
• Internet, router, cameras, phone chargers — 30 W × 24 h = 0.72 kWh
• Computer/laptop — 150 W × 8 h = 1.2 kWh
• Well water pump — 900 W × 0.5 h = 0.45 kWh

Total daily consumption in this example is approximately 4.2 kWh.

Step 2. Choosing the battery bank for your solar system

It is important to remember that batteries should not be fully discharged. LiFePO₄ batteries provide optimal lifespan when used at a 60–70% depth of discharge.

To obtain 4.2 kWh of usable energy at 60% DoD, you need:

4.2 kWh ÷ 0.6 ≈ 7 kWh

In practice, a reserve of 8–9 kWh is recommended to cover load spikes and inverter losses.

A suitable configuration for a 24 V system:

• LiFePO₄ battery 25.6 V 200 Ah ≈ 5.12 kWh
• Two such batteries in parallel → ≈10.2 kWh

This provides more than enough energy to support the daily load and ensures stable operation during longer outages.

Step 3. Selecting the right inverter for your home

Next, determine the maximum simultaneous power consumption of your appliances.

• Circulation pump — 85 W
• Refrigerator — 100 W (starting surge up to 300–500 W)
• Internet and low-power devices — 30 W
• Computer — 150 W
• Well pump — 900 W (starting surge 1800–2500 W)

Nominally this totals about 1265 W, but surges require the inverter to handle at least a 2× overload plus 20–30% reliability margin.

An optimal choice is a 24 V inverter rated at 3 kW, such as:

• Anern AN-SCI-EVO-3200
• Daxtromn SC-HF-3500
• Easun SMH-II-3.2KW

Step 4. Selecting solar panels for daily battery charging

The number and wattage of solar panels for your home depend on:

• MPPT controller specs of the inverter (voltage, current, max power);
• desired charging speed;
• seasonal variations (especially winter generation);
• available roof or ground mounting area.

For a base system, 8 panels of Longi Solar LR5-54HTH-440M create a ~3.5 kW PV array capable of charging the battery pack efficiently during the day.

Extended scenario: adding a boiler, electric kettle, and cooktop

If you want not only essential loads but also comfort appliances such as a water heater, kettle, and electric cooktop, total power demand increases significantly.

• Water heater — 1.5–1.8 kW
• Electric kettle — 1.5–1.8 kW
• Electric cooktop — 1.5–2+ kW

Combined loads can reach 9–10 kW. The best practice is to divide consumers into two groups:

• Main group (≈4.5 kW) — refrigerator, pumps, computer, water heater;
• Kitchen group (≈5.1 kW) — kettle, cooktop, other high-power devices.

Why 48 V systems are better for high-power loads

For loads above 5–10 kW, it is strongly recommended to use 48 V inverters and batteries because:

• current is lower → less cable loss;
• system efficiency increases;
• a wider choice of powerful hybrid inverters;
• easier system scaling.

Popular 6–6.2 kW 48 V inverters:

• Anenji ANJ-6200-48V
• Anern AN-SCI-EVO-6200
• Daxtromn AGH-6.2KW
• Deye SUN-6K-SG05LP1-EU
• Easun SMH-III-6.2KW
• Growatt SPF 6000 ES Plus
• Powmr POW-HVM6.2M-48V

Example: sizing solar panels for Growatt SPF 6000 ES Plus

Consider the Growatt SPF 6000 ES Plus. It includes two MPPT trackers with:

• 2 MPPT inputs;
• maximum operating current: 16 A per tracker;
• maximum PV power per tracker: ~4000 W.

Possible configuration:

• Longi Solar LR5-72HTDR-580M — 8 panels per MPPT → 4640 W;
• 20% clipping is acceptable, so this array is compatible;
• drawback — heavy panels (~31.8 kg each).

An easier-to-install alternative:

• Trina Solar TSM-NEG9R.28-460 — weight ~21 kg;
• 8 panels → 3680 W, within MPPT limits.

Practical tips for choosing an inverter, battery, and solar panels

• Do not choose an inverter with zero margin. If your load is 3 kW, pick a 4–5 kW model.
• Consider seasonality. Winter solar generation may be 3–6× lower than in summer.
• Split heavy loads into separate groups. Avoid running kettle + cooktop + heater on the same inverter simultaneously.
• Follow MPPT limits. Do not exceed current, voltage, or power restrictions.
• Use an online solar calculator. It helps avoid mistakes when designing PV strings and choosing equipment.

Conclusion

Properly selecting an inverter, battery bank, and solar panels for home backup begins with analyzing your actual energy consumption and blackout scenarios. Start with a daily load calculation, then size the battery and inverter with a reasonable safety margin. Finally, design your solar array according to MPPT limits and available installation space.

To simplify system design and avoid configuration errors, use our online solar inverter and panel calculator — it will help you choose the optimal voltage, current, and array size for your needs.