I need to know if anyone who has a good experience on solar space heating would be willing to charge me for a consulting fee in order to guide me with interactive written instructions on how I could learn how to maximize the solar heat that I could store in a 200 gallons solar water tank when the outside temperature is very cold. I also would like to learn, realistically, what is the maximum stored solar water tank temperature I could get during cloudy and non-cloudy days when the ambient temperature feels in the low digits degrees Fahrenheit. (Note: A contractor already charged me for buying and installing six flat solar panels on a roof facing south; the heat is collected by those solar panels, then glycol circulates within those panels and that glycol is sent within a metallic tube into the 200 gallons water tank; the glycol then heats the water within the 200 gallons water tank).

 

 I would be more than happy to see my questions and answers posted in this forum with some people “chipping in” in order to also add good free opinions.

If you know the manufacturer of the panels, you should be able to get the figures from them (their website). Alternatively, you could look for them here: http://www.solar-rating.org/.

There is a - HUGE - variation in the performance of solar hot water panels/collectors. Without knowing what you have installed, there is simply no way to even guess. I have 40 evacuated tubes and they generally produce nothing on a cloudy winter day. However, it could be 8F outside, and as long as it is bright and sunny, I am making 100-120F hot water.

If you post the manufacturer and model number, we might be able to come up with some educated guestimates.

Regards,
Ed

Start with telling us the following info:

1 your zip code or location

2. size of the panels  ex 4X8

3. angle the panels are mounted with respect to vertical

4. exact azimuth the panels are facing

5. model name and model number of the panels.

 

My house where the panels are located is in Yonkers NY zip 10705. We have six flat panels on a side of the roof that is facing south. I will contact the installer to find out the exact size of the panels, the angle they are mounted, etc. They promised me that they would come this Friday to see why I am not getting enough heat being captured during a sunny solar day.

fflorimon,

Check your solar loop for a flow meter. It should show a flow rate when the pump is operating. If the pump is running and you see little or no flow then the air lock Bruce mentioned is probably the problem. Air in pressurized solar loops are easy to get out IF one has the proper location for air vents at the top of the loop arrays.

Ray

I hope this free advice is a good start. First of all, your best first use of money is always insulation. Until the building (attic, ceilings, walls, windows, doors, infiltration, etc.) is well insulated, money spent elsewhere is wasted. In your case you also need to insulate the collectors (double glazing for flat panels), the warm and hot circulation lines, the interior hot water pipes, the 200 gallon tank; any and all slightly-warm-to-the-touch components. Another issue is snow coverage. This is especially critical with evacuated (vacuum insulated) tubes. If the collector is not vertical enough, snow cannot slide off. If the collector is too close to the rooftop or ground, snow can cover the bottom like a snowdrift. For this reason I prefer to elevate the collectors above the snow and angle it closer to vertical. The incorrect angle can be corrected by using a white reflective surface below and in front of the collectors. (Snow works great.) Low outside temperatures will have little to no effect on collectors if the insulation is good enough. If you shine a light into the collectors and see only one pane of glass in the reflection, you need to add another layer of glazing before it gets cold. The transparent shrinking film used to weatherize picture windows or polyethylene film is simple to install. Create a 3/8" to 1/2" gap between the film and the glass with a spacer. You cannot expect cloudy weather to permit the collector to work. That is the purpose of the 200 gallon storage tank. The next issue is stratification temperatures in the tank. I find a lot of heat exchanger coils are in the open at the bottom of the tanks. If the water heated by this coil has a restricted path upwards (like a flue), this allows good stratification; but otherwise it mixes up the contents. Mixing prevents stratification (the highest possible temperatures at the top of the tank and lowest possible at the bottom). If the tank is not hot enough at the top, the water may become dangerous. A tempering (mixing) valve can stop the tepid flow until it is hot enough; in the mean time it can draw water from another heating appliance. You can guarantee stratification by using an external heat exchanger; this also prevents the collector from heating the tank at all until it is hotter than the top of the tank - which I find is quite OK. I figure if you are trying to minimize use of fossil fuels, you should avoid using storage water heaters, especially gas or propane, as a backup. A tank-less gas or propane heater is ideal.