Zenlithic Solar Blog
Solar PV design calculations with formulas, worked examples and checklists.
A step-by-step guide to preparing a solar plant single line diagram (SLD) — the DC, LT and HT sections, protection, metering, earthing and ratings — illustrated with a 2.5 MW plant example.
How to calculate the kVA/MVA rating of a solar step-up transformer, choose impedance and vector group, estimate losses and fault levels — with a verified 2.5 MW plant example.
How to calculate the number of strings per MPPT and per inverter — operating current, short-circuit current, bifacial gain, string fuse requirements and orientation rules — with a verified worked example.
What GHI, DNI, DHI and POA irradiance mean, how they relate, how tilted-plane irradiance is calculated from them, and which one to use in generation, PR and PVsyst — with a verified worked example.
The difference between kW, kWp, MW, MWp, kVA, kWh and MU in solar projects — what each measures, where each belongs in a proposal or tender, and a worked 5 MWp / 4 MWac example.
How to calculate solar row spacing, pitch and GCR from sun position — winter-solstice shadow analysis, tilt trade-offs and land density — with a fully worked example for a fixed-tilt plant in Jaipur.
How to calculate solar plant generation, performance ratio (PR), specific yield and CUF — with a complete 5 MWp / 4 MWac worked example, an explicit loss chain and clearly stated assumptions.
How to size DC string cables and AC/HT cables for solar plants — design current, derating, voltage drop and loss formulas, short-circuit withstand, copper vs aluminium — with complete worked examples.
A practical engineering guide to DC/AC ratio (inverter loading ratio) and inverter sizing — MPPT input limits, clipping threshold calculation, reactive-power headroom and a worked 10 MW example.
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