PV Hot Water System.

[simple_gifts]

Thinking of doing a side project to hook up a solar hot water system in a friend of mine's house.

In the late 1970's my parents installed a thermal solar hot water system (closed loop). Our house was unobstructed and 2 degrees off due south. There was a 120 gallon tank that preheated the water going into the HWH. Pretty much the preheat tank was about 180F year round

So I started reading up on those types of systems, thermosiphon systems and others, and it appears due to the cost and efficiency with PV panels, those other technologies are no longer cost effective. Other problems like plumbing them up, glycol stagnation, freeze issues, etc etc make them a long term maintenance headache. A PV system can be wired up and DC fed directly into a HWH. This is the site that got me looking into it

http://techluck.com/

Two 220W panels and a small controller (but $$) to regulate the PV panel output and that is about it. This, for my friend, would be an "off grid" install an obviously the time to heat up a tank would pretty much be "all day", but it would be a big help.

I'm always wary of internet stuff like this, but it clearly isn't an "HHO" type of scheme. Direct feed DC into a resistive element to generate hotwater. I'm not an EE so, "what goes on" with the controller unit is beyond me.

Panels are about $1/watt now and she has good direct sun on the back of her house. I figure the whole thing could be done for < $1000 (she currently has a propane HWH which isn't running)

Any thoughts.

 

[sleddriver]

I still heat water using a solar system about 30 years after it was installed. It's currently off-line as I had to remove the collectors to re-roof the roof. It uses far less power than trying to heat the water using electricity. Too many losses.

I had an 80ga. tank with 160° water in it. Turned off the breaker in the Spring and only back on during extended periods of cloudy weather during the Winter. The system recirc'd drinking water (no anti-freeze here) and ran off a 30W? little pump. Had far more hot water than I knew what to do with.

Heating water directly with solar energy is a slam-dunk. Particularly here in Central Tx. Whenever it detected freezing temps, it would drain the collectors. Never experienced a problem with them freezing. Further North, you would probably have to use a heat exchanger and anti-freeze. Cars do this all the time.

Saved me major $$$ over 30+ years as I live in an all electric neighborhood. Paid for itself decades ago. My two cents.

 

[earlyre]

Originally Posted By: sleddriver
I still heat water using a solar system about 30 years after it was installed. It's currently off-line as I had to remove the collectors to re-roof the roof. It uses far less power than trying to heat the water using electricity. Too many losses.

I had an 80ga. tank with 160° water in it. Turned off the breaker in the Spring and only back on during extended periods of cloudy weather during the Winter. The system recirc'd drinking water (no anti-freeze here) and ran off a 30W? little pump. Had far more hot water than I knew what to do with.

Heating water directly with solar energy is a slam-dunk. Particularly here in Central Tx. Whenever it detected freezing temps, it would drain the collectors. Never experienced a problem with them freezing. Further North, you would probably have to use a heat exchanger and anti-freeze. Cars do this all the time.

Saved me major $$$ over 30+ years as I live in an all electric neighborhood. Paid for itself decades ago. My two cents.


I've been trying to talk my brother in the DFW area to putting in a similar system for years(either solar HW, or PV)...to no avail...
he's also in an all electric area.
no gas lines in his neighborhood, though there are gas wells.

 

[ac_tc]

Water/ solar exchangers can produce more than 1 kw/ m2
(3,3*3,3 foot??) so it would get rather costly to get that amount of PV cells just to cover a square meter.
You usually diemensions 1 m2 / 100 liters of water.

 

[simple_gifts]

PV is < $1/watt USD; the goal for this effort is low startup cost and ease of install, not finding the most efficient system. We had tons of hot water with the thermal system from the 1970s but in this day and age, the labor of plumbing up such a system would be a deal breaker. If it takes 6 hours of sun to warm the tank, that is ok too. Even a tank of 80F water would be an improvement.