Irrigation Controller Using Estimated Solar Radiation

US07048204

An irrigation controller (200) receives temperature data, and at least partly derives an estimated solar radiation value from the temperature data. A regression model stored in a memory (220) of the irrigation controller (200)operates upon a data point from the estimated solar radiation to estimate an evapotranspiration rate, which is used to affect an irrigation schedule executed by the controller (200). The regression model is preferably based upon a comparison of historical ETo values against corresponding historical environmental values, with the data advantageously spanning a time period of at least two days, and more preferably at least one month. Data from one or more environmental factors may also be used, including especially estimated solar radiation, temperature, wind speed, hnmidity, and soil moisture, and so forth. Values relating the environmental factor(s) may enter the controller from a local sensor (240), a distal signal source, or both.