Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Why do solar panels drain when the pump is off?

  1. Back To Top    #1

    Why do solar panels drain when the pump is off?

    I have a pool with solar panels on the roof of a three storey house and a variable speed pump.

    Why is there a need to drain the solar panels through the vaccuum relief valve?

    It seems to me that if you primed the panels at the beginning of the season, the pump would be able to run a lot slower (because it wouldn't need to maintain the head), and it would be more efficient.

    But there's probably something I'm not thinking of (so I thought I'd ask, before I tried blocking them.

    Thanks!

    (Edit: Clarified title).
    Linda


    12' X 36" Intex Metal Frame Set (2530 GAL)
    2500 gph Intex cartridge pump
    Aquabot Pool Rover Jr.
    Tons of trees and pollen

  2. Back To Top    #2

    Re: Why do solar panels drain when the pump is off?

    The vacuum would damage the panels and cause them to collapse.

  3. Back To Top    #3

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: Why do solar panels drain when the pump is off?

    In particular, without water flow, the panels can get VERY hot and hot PVC is far more likely to collapse under low pressure. When you've got water flow through the panels, you still have somewhat low pressure starting from the top on its way down the return side, but the temperature of the PVC is near water temperature.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  4. Back To Top    #4

    In the Industry

    ps0303's Avatar
    Join Date
    Jul 2011
    Location
    FL
    Posts
    3,435

    Re: Why do solar panels drain when the pump is off?

    To answer the question on the topic "Why do solar panels drain when the pump is off?" is caused most likely by a leak in the system. If your pump is losing prime you have a leak you need to find and fix. The only time panels are drained is if there is a leak in the system like at the pump, or if like here in FL there is going to be a hard freeze, then we drain the panels so they don't burst.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

  5. Back To Top    #5

    Re: Why do solar panels drain when the pump is off?

    Quote Originally Posted by ps0303
    To answer the question on the topic "Why do solar panels drain when the pump is off?" is caused most likely by a leak in the system. If your pump is losing prime you have a leak you need to find and fix. The only time panels are drained is if there is a leak in the system like at the pump, or if like here in FL there is going to be a hard freeze, then we drain the panels so they don't burst.
    Sorry, but I don't agree with this answer. They are "designed" to drain when the pump is off. That's why they have check valves at the top of every set of panels.

    See the answers above about hot temperatures with no flow not being a good combination.
    20,000 in-ground pebble-coat pool with 60sf Jandy DE filter, Pentair Variable-Flow pump, Goldline Aquarite SWG, Dolphin Premiere robot, passive solar heating.

  6. Back To Top    #6
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Why do solar panels drain when the pump is off?

    I agree ... having a setup without the ability to drain (due to lack of a VRV) is likely to result in damage to the panels/plumbing. They will get very hot and the vacuum created by the weight of the water can crush the pipes.

    Jeremy is correct that the most work for the pump is getting the panels primed, once primed the pump speed might be able to be reduced. You could always try running on a higher speed for a few minutes and then backing the speed down. Although realize that the heating efficiency is higher as you increase the flow rate ... for best heating, you want to run as much water through the panels and their design can handle.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •