* If its summer and the blinds have been left open the house can overheat quickly. If its a low energy massive house then its hard to get the heat out again but if its winter then the suns energy is very useful in reducing energy bills and complementing the heating system. I needed way to be quickly alerted if the blinds have been left open and the house is already hot enough. When alerted I can then remotely check on the room temperatures and the effect of the sun. In my case my blinds can be remotely closed using a phone app. The solution also has the benefit of being able to monitor how much sun energy was received and even open the blinds if they were left closed and the suns energy would usefully reduce the heating bills eg in winter *
** Use one or two Mobile Alerts pro temperature sensors with probes and gateway plus a Conrad connect recipe e.g. Techno Line Mobile Alerts Thermo-/Hygrosensor and gateway This sensor has both a room temperature sensor and a cable probe.
One of temperature probes is made into a sun sensor by sticking it inside two black disks. I used two cheap black insulating tea/coffee cup mats stuck together with channel between them where the probe can be inserted. The improvised sun sensor is then stuck to a south facing window where it can soak up the suns energy and heat up the mats. See chart below for sun sensor output. It can get surprisingly hot.
In my case the second mobile alerts sensor probe is then inserted into the air duct that supplies one of the rooms. I have a air ventilation heat recovery system and the circulating air is a good indication of the overall house temperature. This helps prevent false alerts due to sudden rises in temperature when the average house temperature is actually OK and the suns energy would be beneficial. Or you could us the room temperature reading from the improvised sun sensor but in this case the placement could be difficult for an accurate actual room temperature since the cabled end has to be in a sunny window. The idea is to only get alerts when the average temperature is on target and the sun is coming in with the risk of over heating. Brief peaks in temperature from the sun are useful to reduce the overall energy costs
Here is the chart for the sun sensor:
The idea could be extended to create a recipe to also receive alerts if the blinds have been left closed during the day and the forecast is for some winter sun.