As stated into the introduction, this project started under the impulsion of farmers who needed a low cost  Weather Station remotely controled from their farm located at 2km away from their fields.

Currently two models of the station do exist and have proven their reliability.

But is this concept viable in the long term, is there a "market" or even a need for this low cost approach ?

I started  a light "market analysis" for weather stations and found :

quite a lot of solutions in the range 100 to 200$ but almost none with long range Lora transmission.

When looking specifically for "lora weather station" the cheapest I found was the Raddy L7 Lora station, but at a price of 180 USD.

Then come more expensive solutions like Meteo Helix (839€)

None of them seems to have weighing bucket rain gauge and use standard tipping buckets.

Does it mean that my very low cost station at 65€ is "the" solution ?

Well, while searching for evidence on internet I found a very interresting paper called : 

Calibrating low-cost rain gauge sensors for their applications in IoT infrastructures to densify environmental monitoring networks

This paper is a very recent (may 2023) preprint from gi.copernicus.org

(Geoscientific Instrumentation, Methods and Data Systems (GI) is a not-for-profit open-access interdisciplinary electronic journal for swift publication of original articles and short communications in the area of geoscientific instruments).

This paper is available for download and worths spending some time reading it.

I have picked up a few sentences:

"Environmental observations are a pillar of environmental science. They provide the necessary data to describe and model the state of the environment and its spatial and temporal changes. Furthermore, the data collected can be used to identify and assess 20 possible natural risks and thus warn of potential natural hazards. Environmental observations also form the basis for decisionmaking in environmental policy and for monitoring the outcome of the resulting measures, which requires reliable and systematically collected data."

This seems to be perfectly in line with the "save the world" challenge#5 objectives !

 Later they do insist on the usefullness of low cost Weather Stations:

"Developments over the last two decades in the field of the Internet of Things (IoT) allow this shortcoming of institutional measurement networks to be addressed. The availability of ever smaller, cheaper, more power-efficient devices and sensors combined with the ubiquitous availability of connectivity to the internet make it possible to collect and process data where it is needed. Even if the quality and reliability of such devices is lower than that of official measuring stations, the resulting datasets with higher spatial and temporal resolution can represent added value."

And finally, I would like to address the requirements they propose for low cost sensors systems :

"To improve the resolution of any official environmental measurement network, the sensor systems have to fulfil different requirements. When using a high number of sensor systems, they have to be low-cost while maintaining a certain level of data quality and reliability to ensure an effective application. Thus, sensors have to be quality checked before being used. To further reduce costs, the sensor system should be robust and low-maintenance. The proposed systems should be energy efficient so that the systems can operate for long periods of time without replacement or can be charged by solar panels. This would make the systems independent from being connected to the power grid, which maximises the possibilities for measuring sites. For real- or near real-time use of the data, the use of wireless connectivity is required to transmit the data from the sensors to the users. This also improves flexibility in the selection of measuring sites.

The sensor system should be easy to install, use and maintain, ideally even by people not familiar with the subject. This also enables the use of volunteers (citizen scientists) to further reduce costs. Since not all requirements have to be met at all locations, modularity of the system would be desirable; be it the choice of sensors, power supply or connectivity. Further, to make the system as applicable and transferable as possible, open-source hardware should be used."

Frankly speaking this paper wasn't even published when I started my project. I had some intuition of what could be "good" for users but I couldn't imagine that my own specifications would match so perfectly the outcomes of this GI's preprint!

I let you read the full article, where (once again) tipping bucket rain gauge prove their difficulty to be properly calibrated...

But after reading this preprint I feel confident in my specifications and design:

• a battery operated + solar charger
• a wireless long range solution
• precise sensors based on existing solutions
• an accurate weighing rain gauge (calibrated both during tests and with self calibration procedure) 
• an accurate (and calibrated) anemometer
• an accurate wind direction sensor 
• an outstanding 65€ cost
• a full Open Source Open Hardware system

Obviously this system is easy to build and mostly intended for "hackers" community. But it could be easily manufactured and sold either as a kit or as a pre assembled system.

I will stay into the hackers side, but if you are interested, this system is open... Just keep me informed please!