Hybrid Solar System Builder

Estimate PV kWp, panel count, inverter size, battery bank Ah and number of batteries, and charge controller sizing for a hybrid (grid + battery + PV) system.

Inputs

Set hours for backup runtime at average load. Use 24/48 as needed.
Battery usable DoD before recharge (e.g., 80% for LiFePO4, 50% for lead-acid).
Ah rating per battery (e.g., 200Ah at nominal voltage).
Typical full-sun-equivalent hours for the site (e.g., 3–6).
Include inverter, wiring, soiling, temperature losses. Typical 15–25%.
Model notes: estimates are approximate. Use measured consumption data and local solar resource for precision. This builder uses energy balance + simple battery bank arithmetic to recommend sizes and counts.

How it works

We compute required battery energy (kWh) from autonomy × average load, adjust for DoD and efficiencies, then convert to Ah at system voltage. PV size is calculated from daily demand, system losses and peak sun hours. Inverter and charge controller are sized from peak power and PV current respectively.

Practical tip

Prefer higher system voltage (24/48V) for larger systems — reduces battery currents and conductor sizes. Match battery nominal voltage to inverter/charger specs.

⚙️ Understanding Hybrid Solar System Design and Sizing

A hybrid solar system combines solar panels, batteries, and a grid connection to ensure consistent power supply day and night. It stores excess solar energy in batteries during the day and draws from them when sunlight is unavailable or during power outages. This setup provides the benefits of both off-grid independence and grid reliability.

The Hybrid Solar System Builder above estimates the key components required for a balanced setup — including solar array size (kWp), number of panels, inverter rating, battery bank capacity (Ah and number of batteries), and charge controller sizing. By entering your daily energy use, backup duration, and site solar conditions, you can approximate a practical configuration that suits your home or business energy profile.


🔋 1. Estimating Battery Bank Capacity

Your battery bank defines how long your system can run without sunlight. To calculate it, the tool multiplies your average hourly load by your desired autonomy hours (backup duration). For instance, if your home consumes 24 kWh/day and you need 24 hours of autonomy, your usable battery capacity requirement is roughly 1 × the average daily load.

However, not all stored energy is usable. Batteries have a limit called Depth of Discharge (DoD) — typically 80% for LiFePO₄ and 50% for lead-acid. The calculator accounts for this, along with inverter and battery round-trip efficiencies, to estimate the total nominal capacity needed. The result is expressed in both kWh and Amp-hours (Ah) at your chosen system voltage (12 V, 24 V, or 48 V).

Higher system voltages reduce current and wiring losses, making 24 V or 48 V systems more efficient for larger setups. The calculator also determines the required series × parallel configuration (S×P) and total number of batteries based on your selected battery specifications.


⚡ 2. Inverter Sizing

The inverter converts DC from panels and batteries into AC for your appliances. Proper sizing is crucial to avoid overloading or inefficiency. The recommended inverter size is based on your peak power demand with a safety margin of around 10%. For example, if your maximum load is 5 kW, a 5.5–6 kW inverter is advised.

Besides the continuous rating, also check the inverter’s surge power capacity (for startup spikes from devices like refrigerators, pumps, or compressors). The tool gives a balanced estimate for both continuous and short-term load handling.


☀️ 3. PV Array Sizing and Panel Count

Solar panels generate the energy your batteries and loads consume. The system estimates the PV array capacity using the formula:

PV size (kWp) = Daily energy demand ÷ (PSH × (1 − system losses))

where PSH (Peak Sun Hours) represents the average number of full-sun-equivalent hours per day at your location. For example, with 5 PSH and 20% system losses, a household using 25 kWh/day would need roughly 6.25 kWp of solar capacity. A safety margin (default 20%) is added to ensure performance during cloudy periods or seasonal variations.

The number of panels is then computed from the array power divided by the selected module wattage (e.g., 450 W per panel). This gives you an approximate total panel count for purchase and installation planning.


🔌 4. Charge Controller and MPPT Current

The charge controller regulates energy flow from panels to the battery bank, preventing overcharging. Its current rating depends on the array’s total power and system voltage. The calculator estimates this using:

Controller current (A) ≈ (PV kWp × 1000 / System V) × 1.25

The 25% margin ensures safe operation under peak sun and cool conditions when panel voltage rises. For large systems, multiple MPPT controllers or higher-capacity units may be required.


🌞 5. Efficiency, Losses, and Margins

No solar system is 100% efficient. The main loss factors include:

The calculator groups these effects under “System Losses (%)” and adjusts PV sizing accordingly. Adding a small design margin (e.g., 10–25%) ensures stable year-round operation, especially during monsoon or winter months.


🧮 6. Core Formulas Used

The Hybrid Solar System Builder applies simple yet powerful equations:


Average Load (kW) = Daily kWh / 24  
Usable Battery Energy (kWh) = Average Load × Autonomy Hours  
Nominal Battery Energy (kWh) = Usable Energy / (DoD × ηbattery × ηinverter)  
Battery Capacity (Ah) = Nominal Battery Energy × 1000 / System Voltage  
PV kWp = Daily kWh / (PSH × (1 − Losses)) × (1 + Safety Margin)

These values form the basis for estimating required battery and PV sizes that balance storage, generation, and demand.


🏡 7. Practical Design Considerations


🔍 8. Example Scenario

Suppose you have a home with 25 kWh/day demand, 5 kW peak load, 24 hours autonomy, 24 V system, and 5 PSH. The calculator outputs roughly:

This balanced system can run essential appliances, charge batteries daily, and provide autonomy during blackouts while remaining grid-connected for reliability.


📊 9. Interpreting the Results

The output includes both usable and nominal battery energy to help you match datasheet specifications. It also suggests inverter rating, charge controller current, and estimated daily solar production. Use these values as preliminary design guidance before finalizing hardware or consulting a certified installer.


✅ 10. Tips for System Optimization


📘 Conclusion

The Hybrid Solar System Builder is a powerful starting point for homeowners, engineers, and students looking to understand hybrid PV system design. By adjusting input values such as autonomy hours, efficiency, or sun hours, you can instantly visualize how each parameter affects system size and cost. While these results are approximate, they offer a reliable baseline for more detailed engineering, equipment selection, and financial planning.

Always verify design outputs with manufacturer datasheets, local electrical standards, and professional installers before implementation. With thoughtful planning, a hybrid solar system can deliver years of clean, uninterrupted energy — even when the grid goes dark.