First Year kWhac/kWdc bug

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mpdavies
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16 Aug 2014 19:55 #2494 by mpdavies

First Year kWhac/kWdc bug was created by mpdavies

The first year kWhac/kWdc line in the metrics table typically gives a number such as in the attached image: 1,770.

The documentation states: "For PV systems, SAM reports the ratio of the system's annual AC electric output in Year one to its nameplate DC capacity"

I would expect a ratio close to the derate factor, i.e. a number less than one.

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Paul Gilman

19 Aug 2014 16:56 #2495 by Paul Gilman

Replied by Paul Gilman on topic First Year kWhac/kWdc bug

Hello,
The ratio would be less than one if it were a ratio of AC kWh production to DC kWh production, i.e., both values were kWh energy values. However, the metric is a measure of the ratio of the AC kWh production to the DC nameplate capacity in kW. It gives you information about how well the system performs as a function of the manufacturer's rated capacity compared to others.
SAM does report the DC kWh output of the array as "Net dc output (kWh)" so you could calculate the value you describe outside of SAM. To display the value, on the Results page, click Tables, and then click Single Values to expand the alphabetical list of variables. Check the variable's name to display its value.
Best regards,

Paul.

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