PV Gap

Kelly Said:

I want to build a solar hot water system, using a pillow bladder. Can this be done?

We Answered:

Yes you can, but its not a very good idea. Solar panels are typically used for the purpose. They consists of small copper pipes and fins that collect the heat and transmit it to the water in the pipe. Think small increments here, like your coffee pot. The bladder is a big ball of water. The edges would get warm while the middle stayed cold.

There are other problems. You'd have to connect it to the water supply which is under pressure. Does it have connections for that?

Finally, you may be putting more weight on the roof than it can bear. I'd hate to see that bladder in the middle of your living room.

Ronnie Said:

Is it possible, or recommended to use tank less water heater to supplement a Solar Hot Water System?

We Answered:

Absolutely, that's a great combination. The solar preheats the water, and the on-demand heater adds any additional heat if needed. However, make sure the on-demand heater has a couple of things.

#1, make sure the manufacturer allows it to be used in combination with solar. Some companies will void their warranty if the incoming water is hot. Bosch makes a heater specifically for this use, the AquaStar Solar.

#2, make sure the heater is modulating down to 0. In other words, if the water entering the heater is 120 degrees already from the solar, it should turn itself completely off and not add any more heat. If it's 90 degrees, it will only add 30 degrees. Otherwise, if it's a model that just automatically adds all the heat any time water goes through it, regardless of the temp, you won't be saving anything.

Georgia Said:

solar hot water not so hot in mornings.?

We Answered:

The sarcastic answers are correct, no sun in the morning so no solar heated water.

If you have lots of hot water in the evening after a good sunny day I'd say the system works as it should.

The easiest improvement would be to add more insulation to the outside of the water heater tank. This would reduce the heat lost from the tank during the night.

If the insulation doesn't help you might just want to consider making the booster switch turn on automatically.

Most of the systems I've come across (my own included) only use the sun to preheat the water. The solar preheated water is then moved into the "normal" water heater. If the sun doesn't cooperate the regular water heater takes over automatically.

Lastly a long shot possibility-
Some homes contain a system which makes sure you always have instant hot water when you turn on the shower or sink. These systems circulate hot water in a loop so the line always has freshly heated water ready at your tap. Having this type of thing would be constantly using up your heated water over night. If you have something like this get it turned off.

If you ever do find out that your system has some sort of a problem I'd be interested in knowing what it was, please tag me with an email.