# How to calculate amount of energy an area receives from sunlight?

I recently read this article, but is quite unclear on how it got those equations and used them to find the amount of energy (J) an area receives from sunlight over a period of time (s). Does anyone have information or ways to calculate this?

The article shows this equation of calculating it:

$$mJ = (mW/cm^2) \cdot (Area/cm^2) \cdot (Time/s)$$

and subsequent other equations, which have no sources, so I am quite unsure if this is reliable.

$$\theta = 23.5° \sin (2{\partial T/365.25})$$

Solar constant for the day:

$$\sigma D = (137mW/cm^2) \cos (L - \theta)$$

• Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer.
– Community Bot
Jun 21, 2022 at 6:46
• Please avoid links that could break in the future, making this question useless. Take the time to write your question as self-contained as possible (and keeping the link, as a reference). Jun 21, 2022 at 6:47
• @Miyase I just want to know how to calculate the amount of energy an area receives over a period of time from the sunlight Jun 21, 2022 at 7:14
• You mention equations in the question, perhaps you could show them here to support and clarify your question. Jun 21, 2022 at 7:23
• I have tried my best, but I am mainly unsure about how they got the equations and if it is even correct in the first place @Miyase Jun 21, 2022 at 7:47