Difference between revisions of "Frozen Solar Panel Incident"

Revision as of 15:03, 4 January 2012

What We Know

• Date: 1/3/2011
• Time: Approximately 10:30am situation was detected
• Found using the Green Garage HVAC website
  • Solar Panel Air Temp = 195F (sure)
  • T-out for the panels = 64F <needs to be confirmed...very close to correct
  • Pump 9 = On
  • Tank Temp = 97F <needs to be confirmed...very close to correct
  • The evidence indicated that the panels were very hot but no water was running through the panels as T-out was in the 60's (not it's normal 110F).
• Ambient weather
  • Outdoor temp was 18F
  • Sunny with intermittent clouds
  • Wind was moderate (10 mph range) with gusts <needs to be confirmed
  • Wind chill that morning was -2F (from Tom who road his bike!)
• Joe G. took pictures of the panels at about XX:XXpm (< please advise)
  • It showed water leakages inside two panels....Panels #5? and #10.
  • Please place picture gallery here.

What is the sequence for the panel heating?

• Valves and pumps involved in solar heating: Valve 1, Valve 2, Valve 4 and Pump 9
  • Default position
    • Valve 1
    • Valve 2
    • Valve 4
    • Pump 9

What is the location of the failure in the panels?

• Appears to be a fracture in the copper tubing in the thermal transfer body (under the glass) of the panel.
  • Need to confirm location of the failure occurred in the panel system.
• Key Questions

1. Where is the failure location in panels #5 and #10
2. Are they the same?
3. Does it look like a burst tubing?
4. What is the current state of the panels? Frozen water in them? Are they drained?

When did the failure occur?

• Option 1 - It occurred on 1/3/2011
• Option 2 - The leak has been occurring for some time
• Key Questions

1. When was the last time the panels ran before 1/3/2011?
2. What is the tank level? If it's been leaking for a while, the tanks would be low.
3. Any evidence of routine leaking up on the roof? Water...deposits showing steam of water?

What caused the panel failure?

• Potential reason for the leakages:
  • Potential Cause #1 - Panel manufacturing failure
    • Not likely since the panels had been running without leakages (need to be confirmed)
    • Two panels failed in the same spot at the same time
    • Panels were never tested for water flow before installation.
  • Potential Cause #2 - Water froze in the copper tubes causing them to burst
    • Note that the leaks in the two panels were at the same level above the bottom of the panel.
    • Note that the these were two panels later in the series...water is cooler.
• Key Questions

1. What is the best way to determine the cause of the failure? Wait for warm weather and run water through the system. Currently looks like Friday is a good day.
2. What does Alan Rushforth have to say about this?
3. What is the temperature of the pipe / tube at the bottom of the panel that fills first?

Why did the cause of the failure occur?

• IF it was caused by frozen pipes (pure conjecture at this point 1/4/12), why did they freeze?
  • Potential Reason #1 - The water froze because the panels were too cold on the initial filling
    • What temperature was the panel air at the time of filling?
    • Could the water at 97F(Tank Temp) lose enough heat as it was going through the system to freeze?
    • Could all the panels not be the same temp at the time of filling?
    • Could the temp gauge at the top of the panels be inaccurate?
    • Could there be a big difference in the temp at the top of the panel and the temp at the bottom of the panel?
    • Could the programming have an error in it and pump #9 came on too early or incorrectly?
  • Potential Reason #2 - Panels didn't drain properly this time or Panels never drained properly
    • Could design of drainback have a flaw i.e. the panels don't fully drain.?
      • If the leaks are actually 2/3 up the panel this seems unlikely.
      • We have had colder nights and we didn't have a problem...freezing
    • Could valve #? for drainback not open correctly the last time the panels needed to drain?
    • Could the water in the panels have frozen before it fully drained?

How do we recover?

• Option #1 - Repair the panels
  • Manufacturer says that this would be difficult...they are no help
• Option #2 - Replace the panels
  • Could do this first and then repair panels (Option #1) later.
  • Would need to make sure that cause is accurately determined and corrected.
  • Could only run panels when outside temp is above 20F (plus low winds)
• Option #3 - Wait until spring (consistently warmer weather)
  • Better for testing and working out all possible issues
• Option # 4 - Reconfigure from 10 panels to 8 panels.
  • Costly in labor and then need to change back.

Next Steps

1/4/12

• Check on availability of replacement panels and mounting materials (Joe)
• Get input from others...email, phone (Joe, Tom)
• Complete recording of what "we know" section on wiki
  • Research using data from Niagara System
  • Answer ... When did the failure occur?
  • Plan test for Friday with Labs