Live Demo — PV String Configuration Calculator
Enter module specifications and controller input limits to find the series and parallel string configuration for your array.
PV String Configuration Calculator
Free professional PV string configuration calculator for solar lighting systems. Input module peak power, open-circuit and operating voltage, short-circuit and operating current, controller maximum input voltage and current, voltage temperature coefficient, minimum ambient temperature and target array power to determine the series and parallel configuration, verify the low-temperature open-circuit voltage, and get the total array parameters.
Key Features
Module Parameters
Enter module peak power, V_oc, V_mp, I_sc and I_mp from the module nameplate or datasheet.
Controller Input Limits
Set the controller maximum input voltage and current so the array never exceeds them.
Low-Temperature Voltage Check
Apply the module voltage temperature coefficient and minimum ambient temperature to verify V_oc_total stays within the controller limit in cold weather.
Series Count Logic
Computes modules per string from the system voltage using the industry rule of battery voltage × 1.5 / V_mp.
Parallel Count Logic
Derives the number of parallel strings from the target array power and checks total short-circuit current against the controller limit.
Array Summary
Outputs the final 2S1P-style configuration with total power, total V_mp and total I_mp.
Technical Specifications
| Platform | HTML5 Web App | Android (via WebView) |
| Core Calculation | N_series = V_bat × 1.5 / V_mp; V_oc_total = N_series × V_oc × [1 + α × (T_min − 25)] |
| Module Peak Power | 1 - 1000 Wp |
| V_oc / V_mp | 1 - 500 V |
| I_sc / I_mp | 0.1 - 50 A |
| Controller Max Input Voltage / Current | 10 - 1000 V / 1 - 100 A |
| Voltage Temperature Coefficient | Typical -0.14 to -0.19 %/°F |
| Minimum Ambient Temperature | Any (°F, imperial) |
| Target Array Power | 1 - 100000 Wp |
| Industry Standards | IEC 62548, NEC 690 |
| Output | Series × parallel configuration, total power, V_mp_total, I_mp_total + low-temp V_oc check |
Frequently Asked Questions
How is the number of series modules determined?
Series count is set by the system voltage using the industry rule N_series = V_bat × 1.5 / V_mp (empirical factor 1.5-1.8). For a 24V system with V_mp = 33V, that is 24 × 1.5 / 33 = 1.1, so 2 modules are connected in series to reach a suitable operating voltage.
Why must I check the low-temperature open-circuit voltage?
Module open-circuit voltage rises as temperature falls, so in cold winters the array voltage can exceed the controller input limit and burn it out. The check V_oc_total = N_series × V_oc × [1 + α × (T_min − 25)] with α in %/°C (or the imperial 77°F reference with α in %/°F) must be ≤ V_max_controller. Always verify this in cold-winter regions.
How is the parallel string count computed?
Parallel count is driven by power and current: N_parallel = round(P_array / (P_pv × N_series)). You then confirm the total short-circuit current N_parallel × I_sc stays below the controller maximum input current. Too many parallel strings would exceed the current limit.
What does the final array summary tell me?
The summary reports the complete configuration, e.g. "2S1P" meaning 2 modules in series and 1 string in parallel, along with total power, total operating voltage and total operating current. These are the values you use to match the controller and battery bank correctly.
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