If you're interested, you can use this bash script (wcgresults)to write your results to a logfile (using crontab), e.g. each hour like this:

1 * * * *	bin/wcgresults -daf .BOINC/WCG.log

The following items correspond to the numbered columns when using wcgresults, e.g. AppName is in column 1, ResultName is in column 12:

AppName           1
ClaimedCredit     2
CpuTime           3
ElapsedTime       4
ExitStatus        5
GrantedCredit     6
DeviceId          7
DeviceName        8
ModTime           9
WorkunitId        10
ResultId          11
Name              12
Outcome           13
ReceivedTime      14
ReportDeadline    15
SentTime          16
ServerState       17
ValidateState     18
FileDeleteState   19

(see wcglog -C)

Hi. Thank you all for your answers and that script :)

BobbyB, I use a "watts meter" similar to this:
https://www.ebay.com/itm/203279954440

It measures current (A) and voltage (V), therefore power (W = A*V); over time (h), giving the final energy spent (kWh = W*h).
It also displays the lowest/highest wattage during the period and if you enter the price of kWh it displays the cost too. It's pretty cool :)

Over 5 days, 23 hours and 17 minutes my pi spent 0.543 kWh crunching for covid, but since I don't have the points history I can't calculate efficiency.
I used a heatsink to do passive cooling because I think using a fan would affect efficiency too much - so far I'm able to run it at 100% without getting too hot but I'm sure it will when the summer comes. I wrote a script to send a push notification to my phone when the temperature gets to 80oC :)

Apart from installing Raspberry OS Lite (I'm using the full version), I don't know what else could be done to increase efficiency, maybe there isn't a way. to get better.

Nice gadget. I'll give it a try

So it's for stats only from what I can see. There are totals available for download on the overview page "My activity" by day going back a long time and "My activity over time" by project within day going back a long time and then mainMenu-->devices-->selectDevice-->download by day going back a long time.

Yes by device is a pain.

Out of curiosity, how many amps does that Pi draw?

Hey Ives. My home isolation is very bad :) I leave it near a hole in the cat entrance, so it's always cold. My script sends me the push notification before the Pi throttles the temperature.

I've noticed it throttling before, before using the hole wind. If it does that for protection, would it be bad for the chip health to be working like this all the time? I'm ok with it throttling the CPU based on temperature, it's better than doing it myself via boinc manager settings.

BobbyB, ~34mA.