wind uplift testing on the click fit pv mounting system to

Wind uplift testing on the Click Fit PV mounting system to MCS012 Prepared for: Gary Bowden Cleaner Air Solutions UK Ltd 4th October 2010

Test report number 266-082

Wind uplift testing on the Click Fit PV mounting system to MCS012

Test report number 266-082 Commercial in confidence

© Building Research Establishment Ltd 2010 of 18

Prepared by Name Dr P Blackmore

Position Associate Director, Building Technology Group

Signature Approved on behalf of BRE Name Mr D Richardson

Position Director, Building Technology Group

Date 4th October 2010

Signature

BRE Garston WD25 9XX T + 44 (0) 1923 664000 F + 44 (0) 1923 664010 E [email protected] www.bre.co.uk

This report may only be distributed in its entirety and in accordance with the terms and conditions of the contract. Test results relate only to the items tested. BRE has no responsibility for the design, materials, workmanship or performance of the product or items tested. This report does not constitute an approval, certification or endorsement of the product tested. This report is made on behalf of BRE. By receiving the report and action on it, the client – or any third party relying on it – accepts that no individual is personally liable in contract, tort or breach of statutory duty (including negligence).

mailto:[email protected]

http://www.bre.co.uk




Contents 1 Introduction 4 2 Details of the test specimens and installation 5 3 Details of the tests carried out 6 4 Test results 9

4.1 Click Fit hooks at 400mm centres 9 4.3 Click Fit hooks at 600mm centres 14

5 Summary 15 5 References 16




1 Introduction

This report describes testing carried out on the Click Fit PV mounting system for pitch roofs to the draft MCS 012 test method for wind uplift [1].

The MCS012 draft standard specifies the test procedures which shall be used to demonstrate the performance of PV modules and solar thermal collectors and/or their installation kits under the action of:

• Wind loads – resistance to wind uplift forces.

• Fire – resistance to external fire

• Rainfall and wind driven rain – weather-tightness.

These test methods apply to ‘in roof’ and ‘above roof’ systems fixed to pitched roofs. They do not apply to systems mounted inclined above flat roofs or mounted on vertical walls.

This report describes wind uplift tests.




2 Details of the test specimens and installation

The following modules and fixings were supplied for these tests:

• Sharp NU180 Modules

• Aluminium fixing rails, part number 100-1001, manufactured by xxx

• Click Fit roof hooks, size, material, manufactured by xxx

• End clamp, part number 100-3003, manufactured by xxx

• Module clamp, part number 100-3020, manufactured by xxx

The size of the Sharp PV modules was 1318mm x 994mm.

The Click Fit system was installed over Marley Modern flat interlocking concrete tiles by Cleaner Air Solutions staff on the BRE test rig according to the manufacturer’s recommendations, see Annex A.

The Click Fix hooks were installed at nominally 400mm centres for the main tests with a single supplementary test carried out with the hooks at 600mm centres.

The tests were carried out using two PV modules, both of which were loaded during the testing,




3 Details of the tests carried out

The recommended test method in MCS012 for wind uplift testing is based on BS EN 14437:2004 [2], which is a test method originally designed for test wind uplift resistance of roof tiles and slates (other test methods are allowed where these can be shown to give equivalent or conservative results). The tests are carried out on a simulated roof structure comprising rafters at a roof pitch of 45º. Figure 1 shows the BRE test rig with a test specimen in place.

Figure 1 General view of the BRE test rig with the Click Fit system in place




The test products are laid on the test rig as they would be installed in practice on a roof. Pneumatic rams with suction cups were attached to each of the PV modules to apply a force which simulates wind uplift loads. The test requirements are given below:

• Where the flashing or sealing kits provides any uplift resistance then these should be included in the test.

• The roof pitch shall be 45deg +/- 2 degrees.

• A minimum of one solar panel should be tested and the test shall be repeated three times with new fixings each time.

• The uplift load shall be applied using a cable(s) or equivalent methods to provide uniform loads. This\these may be fixed to the solar collector by drilling a hole(s) through the collector or by using suction cup devices attached to the glass cover plate.

• The detailed construction of the test rig in terms of the batten sizes, rafter spacing and all fixings shall satisfy the minimum specification (worst case) of the manufacturer/supplier of the solar panel and all materials shall be of a quality typical of real construction. The minimum requirements of BS5534 shall also be satisfied.

• Where there is a choice of fixing positions, the most onerous (weakest) shall be tested.

The testing was carried out three times using new PV modules, Click Fix hooks, rails and clamps for each test.

The testing was carried out using 9 pneumatic rams attached to suction cups fixed to the glass cover sheets. The suction cups were positioned so that they provided a uniformly distributed load over each of the modules. The loads were applied in a minimum of five increments (as required by the standard). After each load was applied it was removed and the residual deflection was measured. The maximum deflection under load and the residual deflection were measured at three locations; these locations were at the left hand bottom edge of the left module (L1), at the right hand bottom edge of the left module (L2) and on the lower central clamp between modules (L3). The loading cycles were repeated in increasing load increments until failure occurred; where failure is defined as one of the following:

• Breakage of a mechanical fixing between PV module and support frame

• Pull-out or breakage of the mechanical connection between the support frame and the roof structure

• Breakage of the PV module

• The residual displacement exceeds 5mm after releasing the applied load

• The maximum displacement exceeds 75mm

Figures 2 and 3 show the system under test.




Figure 2 View showing the Click Fit hooks deflecting under load

Figure 3 View showing the module end clamp and Click Fit hook under load




4 Test results

4.1 Click Fit hooks at 400mm centres

The results from the tests on the Click Fit system with hooks at 400mm centres are shown in Tables 1, 2 and 3. The displacements L1 to L3 refer to displacement transducers at the following locations: the left hand bottom edge of the left module (L1), at the right hand bottom edge of the left module (L2) and on the lower central clamp between modules (L3).

Table 1 Results from Test 1

Applied Equivalent Force (N) Pressure (Pa) L1 L2 L3 L1 L2 L3

44 34 0.53 0.5 0.5 0.12 0.12 0.14132 101 0.92 0.72 0.58 0.18 0.11 0.2221 168 1.55 1.52 1.1 0.35 0.26 0.28309 236 1.89 1.71 1.23 0.21 0.28 0.28397 303 3.01 2.83 1.9 0.32 0.29 0.28486 371 3.54 3.24 2.25 0.34 0.29 0.31530 404 3.34 3.31 2.22 0.35 0.34 0.32706 539 4.77 4.7 3.26 0.29 0.23 0.3795 607 6.25 6.1 4.28 0.28 0.37 0.36883 674 7.18 7.03 4.31 0.45 0.49 0.43

1059 809 8.08 8.02 5.56 0.45 0.57 0.451148 876 9.44 9.35 6.65 0.43 0.35 0.461236 944 10.22 10.02 7.21 0.55 0.63 0.51324 1011 11.87 11.8 8.55 0.76 0.9 0.71413 1078 12.67 12.8 9.31 0.91 0.99 0.761501 1146 13.49 13.4 9.71 1.14 1.2 0.841678 1281 15.27 15.42 11.27 1.52 1.54 1.011854 1415 17.33 17.7 12.87 2.04 2.11 1.322031 1550 18.3 18.78 13.89 2.26 2.26 1.422207 1685 20.58 21.3 15.66 2.67 2.8 1.742384 1820 23.68 25 18.3 3.1 3.37 2.062560 1955 24.7 27.05 19.9 3.27 3.74 2.262825 2157 24.92 29.81 22.35 3.45 3.86 2.543002 2291 26.77 29.82 25.1 3.95 4.07 2.743178 2426 29.55 33.6 27.44 4.36 4.25 2.883399 2595 33.7 38.38 37.89 4.71 4.78 3.013461 2642 38.3 43.9 46.9 4.99 5.32 4.1

Maximum deflection (mm) Residual deflection (mm)






From Tables 1 to 3 it can be seen that the failure criteria was exceedance of the 5mm residual deflection limit, generally at measurement location 2. The failure load is taken as the loading step before the failure criteria occurred. The failure pressures were therefore 2595Pa, 2575Pa and 2393Pa.

During test 3 the bottom right hand side end clamp on the right hand PV module slipped off during the load increment after the 5mm residual deflection was measured (at an uplift pressure of 2492Pa), this is shown in Figure 4. This caused the PV module to become detached and therefore no longer fixed in place on this edge.

The maximum and residual deflections at measurement locations L1 and L2 are shown in Figures 5 and 6 and Figure 7 shows a tested hook compared with a new hook.

Applied Equivalent Force (N)Pressure (Pa) L1 L2 L3 L1 L2 L3

945 721 4.59 4.69 3.89 0.18 0.34 0.361333 1018 8.68 9.02 6.78 0.23 0.32 0.391775 1355 13.4 13.53 10.34 0.23 0.56 0.712225 1698 18.9 18.85 19.65 0.93 0.42 1.232454 1874 20.56 21.37 16.8 1.1 0.74 1.542702 2062 23.79 24.79 19.54 1.6 1.34 22816 2150 24.48 25.89 20.7 1.78 1.56 2.13099 2366 29.37 30.1 24.2 1.97 1.82 2.33231 2467 30.46 31.66 25.39 2.77 3.1 2.483284 2507 34 35.4 27.85 2.87 3.63 3.543373 2575 34.89 37.88 29.89 3.05 4.97 3.923470 2649 35.4 38.9 31.4 3.23 5.16 4.31



909 694 6.22 5.66 4.52 0.42 0.43 0.541316 1004 10.95 10.3 7.12 0.42 0.53 0.231739 1328 16 14.88 10.62 0.7 0.82 1.182145 1638 21.1 19.18 14.89 1.6 1.63 1.92243 1712 22.1 20.01 15.15 1.87 1.62 2.292322 1773 23.35 20.97 16.06 2 1.9 1.592401 1833 25.1 22.4 17.25 2.37 2.32 32472 1887 25.76 22.93 18 2.55 2.3 3.082587 1975 26.5 24.1 19.15 2.5 2.44 2.762640 2015 28.1 25.5 19.93 3.1 2.63 3.282702 2062 28.5 25.37 20.3 3.18 2.86 3.272763 2110 29.84 26.4 21.19 3.33 3 3.682878 2197 32.47 26.7 22.9 3.97 3.64 4.062914 2224 34 27.86 23.42 4.21 4.14 4.42975 2271 34.76 28.45 24.32 4.51 4.64 4.643028 2312 34.94 33.03 26.36 4.79 4.84 4.743134 2393 37.62 37.35 28.11 5.24 5.53 5.13264 2492 39.2 40.1 32.2





BS EN 14437:2004 requires the characteristic uplift resistance Rk to be determined from equation 1:

Rk = Rx – kn sx … (1)

Where Rx is the mean uplift resistance determined from ∑= ix Rn

R 1

sx is the standard deviation of the resistance determined from ∑ −−

= 2)(1

1xix RR

ns

kn is a statistical factor = 3.37 (for a sample size of 3 from Table D.1 in BS EN 14437)

From the test results:

Rx = 2521Pa

sx = 111.3Pa

Characteristic uplift resistance Rk = 2521 – 3.37 x 111.3 = 2145.9Pa

Figure 4 Right hand module end clamp disengaged from the PV module at a load of 2492Pa




Figure 5 Plot of load versus residual displacement at locations L1 and L3

Figure 6 Plot of load versus maximum displacement at locations L1 and L3

0

1

2

3

4

5

6

0 500 1000 1500 2000 2500 3000

Equivalent pressure (Pa)

Def

lect

ion

(mm

)

Test 1 - L1Test 2 - L1Test 3 - L1Test 1 - L2Test 2 - L2Test 3 - L2

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500 2000 2500 3000

Equivalent pressure (Pa)

Def

lect

ion

(mm

)

Test 1 - L1Test 2 - L1Test 3 - L1Test 1 - L2Test 2 - L2Test 3 - L2




Figure 7 Tested hook compared with new hook showing deflected shape




4.2 Click Fit hooks at 600mm centres

An indicative test was carried out with the Click fit hooks at 600mm centres, using the same rails and modules as for the previous tests with the hooks at 400mm centres.

Table 4 shows the results. From this table it can be seen that the failure criteria was exceedance of the 5mm deflection limit. However as expected this occurs at a lower wind pressure than the tests with the hooks at 400mm centres. From the tests at 400mm centres the failure loads were 2595Pa, 2575Pa and 2393Pa compared with a value of 1880Pa at 600mm centres. This represents a reduction in load capacity of about 35% compared with hooks at 400mm centres.

Table 4 Results from the tests with Click Fit hooks at 600mm centres


415 317 1.12 3.3 2.52 0.05 0.06 0.73521 398 1.19 4.27 3.21 0.07 0.03 0.71592 452 2.55 5.08 3.91 0.08 0.03 0.67733 559 3.36 6.5 4.66 0.09 0.05 0.7883 674 4.8 8.18 5.83 0.1 0.1 0.88

1068 816 6.18 10 7.68 0.12 0.11 0.781316 1004 8.68 13.07 10.09 0.15 0.2 0.751501 1146 11.64 16.2 12.84 0.17 0.5 0.891704 1301 14.15 19.4 15.15 0.4 1.32 1.151819 1388 16.55 21.65 17.48 1.27 2.18 2.161960 1496 18.69 23.9 19.32 1.68 2.3 2.22048 1564 20.37 25.48 20.58 1.83 2.53 2.272172 1658 22.75 28.25 22.79 2.63 3.37 2.532251 1719 24.18 30.18 23.95 2.6 3.69 2.832384 1820 27.86 33.96 27.11 2.88 3.9 3.062463 1880 30.2 27.4 29.2 3.72 4.71 3.642516 1921 32.62 40.2 31.2 4.46 5.12 4.01





5 Summary

This report describes tests carried out to determine the characteristic wind uplift resistance of the Click Fit PV mounting system when tested in accordance with the draft MCS012 guidelines.

It was found that the Characteristic uplift resistance of the Click Fit PV mounting system fixed on to Marley Modern roof tiles with hooks at 400mm centres (installed as described in this report) is 2146Pa.

The failure criteria in all three tests was exceedance of the 5mm residual deflection. However, in one of the three tests with the hooks at 400mm centres, one of the PV module end clamps became disengaged at an uplift pressure of 2492Pa. Although this happened after the 5mm residual deflection had occurred this is potentially a more serious failure mode because exceedance of the residual deflection is a serviceability failure whereas clamp failure is an ultimate limit state failure and should not be allowed to happen because this would leave the PV module restrained in this corner and susceptible to wind damage.

An indicative test was carried out on the Click Fit mounting system with hooks at 600mm centres. It was found that the uplift resistance was approximately 35% lower than the uplift resistance with hooks at 400mm centres.




5 References

1 MCS012; Microgeneration Certification Scheme, Roof performance tests for solar thermal collectors and PV modules, draft 8, September 2010.

2 BS EN 14437:2004, Determination of the uplift resistance of installed clay and concrete tiles for roofing – Roof system test, BSI, 2004




Annex A - Fixing instructions for the Click Fit system


==============REPORT ENDS============= Test report number 266-082 Commercial in confidence


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