I haven't read the entire thread, not even this entire message, so forgive me if I'm stating something obvious or something already covered. Just ignore me in such a case.
----- Original Message ----- From: "Jean-Yves Avenard" <[email protected]> To: <[email protected]> Sent: Monday, December 14, 2009 12:11 PM Subject: [rrd-users] Question about averaging daily ; but with 5 min. steps > the aim of my calculations is to monitor how much energy I output to > the electricity grid via solar panels. Energy is measured in Joules. 1 kWh is just 3600000 Joules. > I have two RRD files ; one containing my power usage ; stored as GAUGE > ; as watts . As we get charge in Watt/Hour (Wh) I perform the > calculation using CDEF to transform watts over time into Wh. Wh is not watt/hour. Wh is watt*hour. kWh = 1000 Wh = 1000 J/s * 3600s = 3600000J. > The 2nd one is for the solar output, this one is a DERIVE counter of a > Wh value reported by the solar inverter that converts DC to AC. So basically it is a joules counter. You can use derive if you want although counter should also work (unless your solar panels actually use electricity from time to time). Make sure you understand W=J/s and kWh = 1000*3600*1J. Inside rrdtool everything is <something> per second, so inside rrdtool you should store Joules (or, if you want, kWh) which will show up as Joules per second aka Watt. Everything follows from that and you should have no difficulties processing your data. HTH Alex _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
