It isn't clear to me from your post what kind of solar water heater you have. We have had a solar water heater installed for 2 years now. Ours are the model that has what looks like standard water heater turned on its side with glass tubes coming out of side. It has provided our guests hot water(we rarely if ever use hot water ourselves) in rain or shine. In cloudier weather it does take longer to recharge but we have yet to run out of hot water. One thing that we have done is once a year have someone come out and flush the system because of the extremely hard water in the area causes significant mineral build up if it isn't maintained. Perhaps that is the problem with the unit where you are? "

29 Dec 2023

@ hromero

I suspect that it is a basic economical system.
It is quite obvious here, that the owner tends to skimp on things, including the construction of the rental unit.
The flushing recommendation sounds like a good idea, that I'll suggest to the owner.

At any rate, what it boiled down to (pun intended) was the no sun/cool weather we had earlier in the week for around 3 days or so, didn't have sufficient solar energy to heat up the water in the system.
Once the sun came out again, it is back to " normal " with adequate agua caliente.

Geronimo

I also looked at getting “tankless” hot water, but the same issue arose.

I ended up getting electric water heaters powered by solar panels. Well, that was the plan, but adding the electric water heaters, electric induction cooking surfaces, and another AC unit has pushed me beyond the solar production capacity. So now I have to augment my solar array.

My original equipment is Solis, but there is no Solis installer locally. So now I have to find another solar installer that can integrate a system. I also need it to be scalable so that when I eventually get a pluggable car I’ll be able to upgrade the solar production.

Solar. Needs sun to work. Not heat, not temperature, but actual solar so it can produce. We were installed Nov 30, and watch it on line pretty much constantly. We are still intrigured. It can be HOT, but unless the panels actually have the sun beating down on them, they don't produce much.

Probably the same with your intallation. Batteries? Storage devices? Not often used here, we do usually have LOADS of sunlight, and it keeps the cost down really low. The cost for our panels which produce 50% more than we use was ridiculously low.

The "hot" water in this rental is via solar panels.
Haven't had any warm/hot water for around 3 days or so,
which pretty much coincides with the clouds and cool weather aquí en Z this week.

The owner says it's due to the weather, no sol = NO agua "caliente ".
Sometimes it is cloudy, but HOT at the same time, vs now cloudy and very cool as well.

Can someone in the know comment about it please?