How to get a full month graph for solar radiation?

[zachsmail2925]

I’ve seen graphs of data for a month or more posted online from the Tempest, but I cannot figure out how to get that from my own Tempest.

I can get info for one day ie, solar radiation, by clicking on that metric, and a graph shows up, but I have tried everything I can think of, both in my app and on the website, and nothing.

I am on Mac OS Sonoma, if that makes a difference.

[eric]

maybe use the tools to zoom in and out ?

[zachsmail2925]

O…M…D! Mine are tucked away in the bottom left corner, I NEVER saw them until you pointed out that they existed.

THANK YOU!

[eric]

That means you installed the iOS app on your mac. What I show is the webpage version that you can access via https://tempestwx.com

use the same credentials as on the app.

[zachsmail2925]

OK, got there. I take it we can only get the current month’s data, not historical month-by-month?

[iladyman]

Hi @zachsmail2925 ,
If you are viewing your graph in a browser window on your Mac use two fingers to slide the graph sideways to view history.
If you wish to get your history into a spreadsheet that is also possible. Use the search magnifying glass to find how to do that. By searching for ‘excel’ I found this…

Excel trick to get data directly from tempest

Did you know you can get your data of your tempest directly into Excel? First you need to generate a personal token. Sign in to the Tempest Web App at tempestwx.com, then go to Settings → Data Authorizations → Create Token, then copy that token. Open a blank new document in Excel. Click on Data (in the menu bar at the top), select (in the top left corner) Get Data → from other sources → from the web paste the following url in the popup window and use your device id (not your station id!) and …

cheers Ian

[zachsmail2925]

Thanks! I have bookmarked that solution. We’re doing solar feasibility work, so having our own data will be very helpful in this process.

[iladyman]

Hi @zachsmail2925
Be aware that your Tempest solar sensor does not face the sun. It is a horizontal flat surface. To measure the ‘actual’ solar energy the Tempest sensor should be perpendicular to the sun. That would only occur if the sun is directly overhead. It means trying to match solar panel generation to the solar W/m2 measured from the Tempest requires some trigonometry which changes every moment or by mounting your Tempest at the same angle as your solar panels.
Searching on ‘solar’ returns this thread where I mention the issue.

Using solar W/m2 to determine solar panel efficiency

Hi @matias.bjorklund , This thread that I moved your post to discusses your question. You probably realise that W/m2 is measured on a flat surface horizontally which means the measurements from your Tempest if you live near the equator will read a greater amount of radiation than if you lived near the poles for the same amount of radiation from the sun. edit. You can also use your tempest to help decide what angle to mount your panels. Rather than converting the horizontally recorded W/m2 val…

cheers Ian

[zachsmail2925]

But, the error would be on the underestimating side, and not over-estimating side, correct? It would at least give us a rough idea at what we would be looking at.

We’re looking at passive solar air heating for an outbuilding, with some solar panels to feed lighting and small water recirculating pumps for hydroponics…

[iladyman]

There is no significant error if you apply your correct calculations and adjust for the angles.
For your passive heating as an example I imagine you want morning sun in winter which begins from sunrise. At sunrise the low angle of the sun will stream almost horizontally into your building and produce good warming including onto your body if you are standing in the window. BUT at that time the sensor of the tempest facing vertically upwards is only receiving a small amount and is reading very low compared to actual warmth coming in your window.
Then in midday in the middle of summer when the sun is at its highest point it is directly facing the solar sensor which will read its maximum but depending on your building design if it is a tall building then the amount of passive heating is not proportional.

From my experience of electricity generation and battery charging rather than calculating the average amounts you should find the most difficult period where you wish to maintain sufficient charge and provide for that. Then the rest of the year will be fine.
So go to where you see your cloudiest overcast dark wet short days for several days in a row.
Find where your battery would have been fully charged prior to the shady event.
Now calculate your demand of the lights and pumps over the shady wet period and compare how much sun energy you received to calculate how many panels and size of your battery.
cheers Ian

[zachsmail2925]

Thanks, this is a great explanation.