Greetings.l would appreciate if someone can share his/her experience regarding the PV water heater Mppt controller sold by sunpay.

Unable to comment on the MPPT?

However I feel that it is better to have solar PV, that I can use anywhere rather than dedicating it just to a geyser for limited use only?

Possibly rather consider installing PV solar for the house etc. and use solar PV or the excess solar PV to heat the geyser as well? This way you get maximum payback on the solar. You may have to change the element to a 2kw heating element? Dependent on the size of pv system you install?

It also depends on your overall use case and personal considerations.

To reduce power consumption, heat pumps are also favored, if that's the goal.

On 2025/05/03 at 3:12 PM, Golden said:

Greetings.l would appreciate if someone can share his/her experience regarding the PV water heater Mppt controller sold by sunpay.

Direct thermal solar geyser water heating panels would be way more efficient and less costly. PV panels are better used to produce electricity for the household.

Another issue comes to my mind: Feeding the geyser with DC could lede to serious problem with the thermostat. Those electromecanical devices are build to switch AC but could fail with DC.

Edited May 5, 20251 yr by Beat

1 hour ago, Beat said:

Direct thermal solar geyser water heating panels would be way more efficient and less costly. PV panels are better used to produce electricity for the household.

Another issue comes to my mind: Feeding the geyser with DC could lede to serious problem with the thermostat. Those electromecanical devices are build to switch AC but could fail with DC.

Luckily we know not to feed DC to the AC thermostat and heating via panels MUST be done via a relay coil connected to the thermostat or using a PV to geyser controller.

One point I would like to raise which is a major plus that I have not seen raised.

When using a heat pump one can always tap the hot water coming out of the heat pump before it enters the geyser and use it to a tap that is just partially open. This off take can be at over 45 degrees even if the water in the geyser is say at 25 degrees. I tested this 13yrs ago when installing my heat pump but it has fallen by the way side as a plus point. I retested it recently when I needed hot water to do dishes.