Solar Panel Recomendations

[poolgladiator]

I am planning to install (DIY) solar collectors on a south facing low pitch shingled roof above our inground pool. The roof is 23 x 13. Pool is 18 x 34 kidney shaped vinyl liner. Approx 600 sq ft of surface area. I have a 175K BTU natural gas heater and would like to use the solar to supplement. The roof gets full sun and unfortunately the pool does not. Goal is to increase temp during regular swim season and not necessarily extend our season. I inquired with powermat (Hot Sun Industries) and have also seen several vendors on ebay and the internet pool suppliers. Powermat recommended eleven 2 x 12 collectors. Any help from members who have gone this route would be appreciated. I do plan to install this system myself. Some questions that I would like help on are.......

1) Which brand collector?
2) Recommended supplier or dealer for the DIY'r?

Location.... North Carolina
Pump.......3/4 hp Svc Factor 1.27
Plumbing......1 1/2
Filter........Sand
Pressure.......12 to 15 psi
Height from pump to roof.....Aprrox 20 ft

Thanks!

 

[kirbinster]

Fafco panels which can be had on e-bay work reall well. I have two 2'x20' panels laying on the ground that I use to supplement my heatpump during the summer. They provided enough heat last summer that once the pool (20x40 ig) was up to temp the heat pump was not needed.

Don't know if your pump will have enough power to get things started up the roof. As a quick test you might want to connect 20' of 1.5" pipe and stand it vertically connected to the pump and see if it can lift the water.

 

[mas985]

If you have a head curve from your pump, the maximum head of the pump (usually around 80 feet), needs to be at least 5' higher than the tallest point of the solar panels. Usually this is not a problem since most pumps will well exceed 25' of head.

 

[kirbinster]

If you have a head curve from your pump, the maximum head of the pump (usually around 80 feet), needs to be at least 5' higher than the tallest point of the solar panels. Usually this is not a problem since most pumps will well exceed 25' of head.

True, but 25' of head would not even get you close. You would be very surpised about the equivalent length that is added for all those elbows and tees, not to mention the filter and any heater - not to mention the pressure drop across the solar panels.

 

[JasonLion]

poolgladiator, welcome to TFP! The short answer is that it should work with that pump but it is difficult to be sure without knowing more about the pump. Ignore the next paragraph unless you enjoy technical stuff.

kirbinster, I think you are mixing up static head and dynamic head. To prime the panels all you need is enough static head to get to the top of the panel at zero flow rate and thus zero dynamic head. Once the panel is primed you have to figure out the dynamic head and flow rate and from that figure out the pressure at the top of the panel to make sure that it is at least a couple of psi while ignoring the static lift. The static lift gets canceled out by the drop coming back down from the panel. There needs to be positive pressure at the top of the system to make sure the vacuum beaker valve doesn't open. Most medium/high head pumps will be able to handle 25'.

 

[mas985]

Theoretically, you could prime a panel on top of a building which is 20' high with a pump that has only 25' of head. When close to the maximum head of a pump, the flow rate is very slow and there is little dynamic head loss so with 5' of margin, it is possible.

Anyway my only point is that you only need just a little more head than the height of the building to prime the panels.

Once the panels are primed, the static head loss nets to zero and the flow rate will pick up.

 

[kirbinster]

Yup, stupid me. You are right about the head calculations.

 

[tphaggerty]

I would go with 4x12 panels. Fafco makes these as does Sun Industries, Heliocoil and others. Sun Industries is what I have, there are quite a few East coast installers that will also sell you the equipment.

The 4' panels will require a lot less connectors than 2' panels, you could go 5 4x12 panels which gives you 240 square feet. You are going to need the 3' extra to handle connections and such. The 12 footers are going to be tight on a 13' roof, you have to angle the panels (I think you only will need a few inches to do that), but the panels may be right up to the edge of the roof. May not be clean looking, so you may have to go with 10' panels (some places will do custom lengths for not much more, then you could possible do 11').

 

[poolgladiator]

Thanks for the info

Thanks to everyone for the info. I went with the twelve 2 x 12's made by Fafco and the Goldline 235 controller. Purchased from online discount pool store. If I have any issues with my existing pump I will ask the guru's here.
J