Author Topic: Solargeyser + PV panel winter boost.  (Read 2943 times)

diepes

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Solargeyser + PV panel winter boost.
« on: May 25, 2013, 05:53:19 PM »
I recently got a Solargeyser with evacuated tubes installed.

I was a bit disappointed with the amount of time the Geyserwise element in the geyser needed to run to keep the water temperature at a acceptable level, but it was very cold the last 2 weeks.

Watching your videos and talking to the installer about sizing got me to thing that the problem with Solargeyser is that you have too little heat in winter and too much in summer.

This got me thinking that having PV(electiricity) would be easyer to controll, and to eliminate some of the inverter/battery cost, why not connect PV pannel output directly to geyser element.
I can't see any reason it wont work fine with DC if it works with AC.

My calc.   2.2kw Element @ 220v , uses 10Aac current, with approximate element resistance of 22ohm.
Thus a PV panel @44v output, will need to deliver 2Amps, I understand this can be improved with some PeakPowerTracing, i was thinking of putting enough panels in series to get to optimal VA for panels into 22ohm's, eliminating complex DC-DC electronics.

So simple design, have +- 1kW panels, in Summer run pool-pump, and in winter add 1kW to Solar-geyser.
Should be able to work with relatively simple relay set-up that can even switch between DC and 220vAC for geyser.

Main goal is to save power, not off grid.

SeanB

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Re: Solargeyser + PV panel winter boost.
« Reply #1 on: May 26, 2013, 01:37:40 AM »
Not going to be terribly efficient at heating water though, you are losing 90% of the heat energy converting it to electricity.  You just need to get to 220V from the panels to connect direct, so will need  5 44V panels in series, and then 5 strings in parallel to get the 2kW of power, if you are just doing resistive heating you do not need precise control, just a Dc contactor that can handle the load without problems. The elements will work off a wide range, from about 180V to 260V will work for an off the shelf element, and you can get them custom made ( spa bath heaters) for other voltages if needed.