🔌 Calculadora de dimensionamiento de strings FV
Diseñe un string FV frente a los límites de tensión de su inversor: Voc y Vmp corregidos por temperatura, la ventana MPPT y la relación CC/CA. Evita sobretensión en clima frío y subtensión en clima cálido.
🔌 Module & Inverter
📊 String Design
Para diseñadores e instaladores solares que dimensionan strings según las especificaciones del inversor.
Cómo se calcula
· Voc en frío: Voc_max = Voc × (1 + α × (Tmin − 25) ÷ 100), α ≈ −0.34 %/°C.
· Vmp en caliente: Vmp_min = Vmp × (1 + α × (Tmax − 25) ÷ 100).
· Máx. módulos = floor(Vmax ÷ Voc_max); mín. módulos = ceil(MPPT_min ÷ Vmp_min); objetivo ≈ Vmax × 0.85 ÷ Vmp.
Normas de referencia
| Standard | Scope |
|---|---|
| IEC 62548 | Sistemas fotovoltaicos — requisitos de diseño |
| NEC 690.7 | Tensión máxima de sistemas FV |
Ejemplo resuelto — módulo de 550 W, inversor de 10 kW
1. Módulo de 550 W (Voc 49.5 V, Vmp 41.5 V), inversor de 10 kW (Vmax 1000 V, MPPT 90–520 V), Tmin −10 °C, Tmax 60 °C.
2. Voc en frío = 49.5 × (1 − 0.0034 × (−35)) = 55.4 V; Vmp en caliente = 41.5 × (1 − 0.0034 × 35) = 36.6 V.
3. Máx. módulos = floor(1000 ÷ 55.4) = 18; mín. = ceil(90 ÷ 36.6) = 3.
4. Recomendado ≈ round(1000 × 0.85 ÷ 41.5) = 18 módulos por string.
FAQ
How do I size a PV string against inverter voltage limits?
The string's temperature-corrected open-circuit voltage Voc must stay below the inverter maximum (commonly 1000 V or 1500 V), and the operating voltage Vmp must stay inside the MPPT window. Use the module temperature coefficients: Voc rises roughly 0.25-0.35%/deg C below 25 deg C. A 550 W module with Voc 49.5 V allows about 18-20 in series at -10 deg C on a 1000 V inverter.
What DC/AC ratio should a PV system use?
DC/AC ratio is array DC capacity divided by inverter AC rating. Typical values are 1.1-1.3 for most sites, up to 1.5 in high-latitude or high-albedo locations, to capture more energy when modules rarely reach STC output. Over 1.3-1.4 the inverter clips more peak power, and the marginal energy gain falls below the extra module cost.
Why does temperature affect PV string voltage?
Solar cell voltage drops as temperature rises. Module datasheets give temperature coefficients, typically -0.29%/deg C for Voc and -0.34%/deg C for power. At -10 deg C the voltage is about 10% above the 25 deg C value, so strings must be short enough not to exceed inverter limits in winter; at 70 deg C the voltage is ~13% lower, so strings must stay above the MPPT minimum.
How many modules per string is typical for a 550 W module?
With a 550 W module (Voc ~49.5 V, Vmp ~41.5 V) on a 1500 V inverter, strings of 28-32 modules are common; on a 1000 V inverter, 18-22 modules. The exact count depends on the minimum site temperature and the inverter MPPT range, so the calculator checks both the -10 deg C Voc and the 70 deg C Vmp bounds.
What is the difference between 1000 V and 1500 V PV systems?
1500 V systems allow longer strings (fewer combiner boxes, less cable and DC loss) and cut balance-of-system cost about 3-8% for utility plants, but need 1500 V-rated modules, inverters and protection. 1000 V remains standard for rooftop and small C&I. The calculator's string designer supports both voltage classes.
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Estimaciones de referencia (FOB Qingdao, EXW) solo para diseño preliminar — no constituyen una cotización final. Confirme el dimensionamiento según su proyecto y las normas locales.
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