A bit over 20 years ago we replaced a failing electric storage HWS with an electric boost Solahart. Now the Solahart is in its twilight years and I’m looking at options to transition to a reasonable arrangement for the future.
For the last few years I have had a temp sensor against the tank underneath the insulation and temp logged every 15 minutes by an RPi. From looking at the data I know the tank will drop 8 degrees overnight (without water drawn) and requires about 1 hr of boost to raise the temp 8 degrees when there is negligible heat radiation around. So, the tank loses about 2.5kwhr each night and is electrically replaced probably 6 months of the year.
If I look at rough capital costs I could replace with a Solarhart (at recent service tech said around $4400) and it looks like a replacement electric storage unit is around $1500) but I can’t seem to find any info on losses of current models which I assume is fairly critical in selection criteria these days. Does anyone have any data on losses?
My thoughts are now is the time to do the numbers on a PV system with a ~$3000 head start to power an electric storage HWS rather than solar HWS.