Weather Station Project #15 - Calibration Procedures for the DIY Solar Radiation Sensor

First of all, I am an engineer, not a statistician. I am trying to come up with a way of calibrating a DIY solar radiation sensor on the cheap. The original question that I asked can be referenced at the My Weather Station subreddit.

First some background: I am building a solar radiation sensor (measures watts/meter²⁾ from a TSL2561 luminosity sensor. The sensor will be placed under a pane of glass, coated with white translucent paint for light dispersion. The output of the sensor will be a number, representative of lux received at my house. I have 5 personal weather stations within a 15 mile radius who have expensive solar radiation sensors from which I can obtain data readings via Weather Underground. Given that cloud cover will alter the readings in each case, I am assuming that a statistical analysis is warranted. The data is also at the same time somewhat spatially distributed. I need to get the value from my DIY sensor into the ballpark of the other sensors.

My approach so far:

1. Gather the data from the 5 sites each day for an extended period of time. 
2. Use a Chi-square test to check if the data samples are likely from within the same distribution set (note that solar radiation results tend to follow an almost bell-shaped curve over the course of a day). 
3. Use a sample T-test to establish a mean and standard deviation representative of the set which varies throughout the day. 
4. Use the mean applied against the value determined by my DIY sensor to formulate an equation (assume a linear fit for right now). 
5. Check the altered output of my DIY sensor against values from the other 5 sites in a Chi-square test to determine if I am likely from the same distribution. 
6. Run some sort of correlation against the data set to further solidify the equation that I have found.

Question: is this approach viable? Are there any glaring issues with what I am trying to do? Is there anything else that might solidify the accuracy of the calibration?

To Be Continued ...

Weather Station Project #14 - Calibration Ideas for Solar Radiation Sensor

I have been mulling over the Solar Radiation Sensor and the UV Sensor and how those would be calibrated.  I have succeeded in getting the two main sensors connected to the Arduino.  The connections for the TSL2561 (for Radiation Sensor) is done according to instructions found at Adafruit - TSL2561 Luminosity Sensor. The connections for the SI1145 (for UV Sensor) is done according to the instructions found at Adafruit-si1145-breakout-board-uv-ir-visible-sensor.  I might be able to make do with the one SI1145 sensor, but the visible sensor is not calibrated.

Unfortunately, I will need to have each of these sensors under some sort of a window material.  The UV sensor will need to go under some type of window.  From the Cancer Research UK website, "UVA mostly causes skin ageing and research has now shown that it is also likely to cause skin cancer. UVB causes redness and sunburn and is a major risk factor for all types of skin cancer.  Most glass used for windows blocks UVB but not UVA. This means that although glass might reduce the risk of sunburn, it does not prevent long term damage from UVA."  In addition, I know that polycarbonate plastic will block most UV.  I am not sure of the window material that I should use for this.  It seems appropriate to use ordinary glass since that passes half of the UV radiation.  The luminosity sensor should be okay if placed under ordinary glass. I will of course need to hard mount the sensors on top of the Arduino - possibly substituting a Gertduino on top of a Raspberry Pi to transmit the information.

When I say calibrated, I mean outputting values that are statistically in-the-ballpark of sensors costing many times more.  What I will need to do is to correlate the output of these sensors over a period of time against local area sensors costing many times more.  The idea is that whatever values come out of the sensors can be modified to be statistically within the ballpark of the highly calibrated devices.  I would assume that I would need to form some equations so that the output of my sensors match that of others within the area.  The thing about my sensors is that they will follow the same curves as other sensors, taking out for cloud cover, etc.  and should be able to be mathematically stretched to match.  This will form the basis for my calibration and over a period of time should prove out to be accurate.

Still Having Issues with Netgear G54/N150 Micro Adapters

I hate to say it but I might have to move on with this development.  I have not been able to get a functioning 8188cus driver to run in the RPi despite trying just about every known driver setup program that is out there.  I don't know what is happening here.  It seems like the newest versions of the Raspbian OS are not able to take the 8188cus driver and allow it to run.  I keep having the rtl8192cu come up in its place and that one does not allow the iw utilities to run with it.

Out of all of the 802.11n based adapters, the Netgear G54/N150 Micro was the one that worked out of the box without any changes.  But it seems that the rtl8192cu driver does not allow the adapter to perform all of it's intended functions.