Plan microinverters using module and site conditions. See sizing checks, branch limits, and risks. Download clear CSV and PDF reports now.
Use these sample entries to compare typical module and microinverter ranges.
| Module (W) | Voc (V) | Isc (A) | Micro AC (W) | Micro max DC (W) | Max V (V) | Max I (A) | Typical DC/AC |
|---|---|---|---|---|---|---|---|
| 400 | 49.0 | 10.2 | 300 | 420 | 60 | 13 | 1.30 |
| 420 | 49.5 | 10.8 | 350 | 460 | 60 | 14 | 1.20 |
| 455 | 52.0 | 11.0 | 384 | 500 | 65 | 15 | 1.18 |
The calculator uses a conservative temperature adjustment from 25 degC to your minimum ambient.
Always verify against the manufacturer datasheet and local electrical rules before final design.
Microinverter sizing begins with module nameplate watts, then checks voltage and current at cold conditions. With a 420 W module and one module per unit, effective DC per micro becomes 412 W after 2% allowance. If the micro continuous AC rating is 350 W, the actual DC/AC ratio is about 1.18, which typically limits clipping while improving annual energy.
To support financial comparison, total system DC is module watts multiplied by module count, while total system AC is micro AC multiplied by micro count. These totals help estimate capacity factor, export limits, and expected clipping under high irradiance and temperatures for long-term ROI planning.
Many residential designs target 1.15 to 1.30. Below 1.10, hardware cost per watt often rises. Above 1.35, midday clipping becomes more likely on clear days. This calculator flags risk bands: Low under 1.25, Medium from 1.25 to 1.34, and High at 1.35 or above. Use the recommended AC value to align your target ratio.
Cold Voc is estimated from your Tmin using the module temperature coefficient. For example, Voc 49.5 V, TCvoc −0.29%/degC, and Tmin −5 degC gives deltaT 30. Voc(cold) becomes roughly 53.8 V. If the micro maximum input voltage is 60 V, the margin is about 6.2 V. Low margin should trigger a datasheet review.
Current increases slightly as temperature drops. With Isc 10.8 A and TCisc 0.05%/degC, the same 30 degC delta raises Isc(cold) to about 11.0 A. Compare this value to the micro maximum input current. When using two modules per unit on dual-input models, repeat the check per channel, not only total.
Branch sizing uses a continuous loading approach. Output current per unit is estimated as micro AC divided by grid voltage. At 350 W and 240 VAC, that is 1.46 A. A 20 A breaker allows 16 A continuous, supporting about 10 units per branch. The calculator reports max units and estimated branches to guide early layout and conduit planning.
It compares effective module DC per microinverter to the micro’s AC rating. Higher ratios can boost annual energy but increase clipping at peak sun. Many designs land near 1.15–1.30.
Module voltage rises in cold weather. If cold Voc exceeds the micro maximum input voltage, shutdowns or damage risks increase. Use the cold-voltage check as a conservative screen before final verification.
Use a realistic low design temperature for the site, not an indoor value. When in doubt, choose a colder Tmin to add margin. The voltage and current checks become more conservative as Tmin decreases.
Not always. It means at least one input approaches or exceeds a limit, or the DC/AC ratio is high. Confirm datasheet ratings, input channel limits, and local requirements before accepting the design.
It is a planning estimate using micro AC divided by grid voltage and an 80% continuous allowance on the breaker. Real limits can change with trunk cable ratings, manufacturer branch limits, and jurisdiction rules.
Use CSV for spreadsheets and quick comparisons, and PDF for a clean record. Both exports capture the key checks and highlights shown above the form, making review meetings faster.
Disclaimer: This tool provides planning estimates only and is not a stamped engineering design.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.