Mounting solar panels on a metal tile roof

Fixings and rails

• Metal tile: Hanger bolt M10×200 + L-bracket + EPDM → rafters. Hole at the crest of the corrugation, EPDM washer + sealant.

Check before installation

• The rafters’ section and spacing, from the attic. The spacing decides which rafters get brackets; the calculation numbers them in the installation steps.
• What lies between the sheet and the rafter: battens, counter-battens, insulation. The hanger bolt must pass through all of it and enter the rafter to the depth given in the steps.
• Where the array sits relative to the eaves and the gable. Near the roof edge the wind is stronger and the calculation places fixings closer together.

Calculation for three cities

A typical 12 × 7 m slope at 30°, rafters every 600 mm, 20 panels of 2,350 × 1,100 mm in 2 rows. Snow and wind under DBN V.1.2-2:2006 for the regional centre; a 6 m high house.

Uplift and pressure are the design forces on one fixing next to the typical capacity the calculation assumes. An array near the eaves or the gable lies in the wind edge zone, where the calculation places fixings closer together.

In all three cities the typical roof passes with the fixing spacing the calculation chose.

Drawings

Bill of materials for the typical roof (Kyiv)

20 panels, 11.00 kW. Quantities from the calculation for Kyiv; open the constructor for your own roof.

Installation step by step

The Solispec engine writes the steps for the typical roof in Kyiv: rafter numbers, marking out and quantities come from the same calculation. Steps that depend on the roof covering are given in full, those shared by all pitched roofs in short.

1. Roof inspection: from the attic, check the rafters (section ≥ 50×150 mm, no rot or cracks, spacing ~600 mm) and the condition of the roof covering.
2. Mark out the 11 180 × 4 720 mm array: 1 190 mm from the eaves, 410 mm from the left gable.
3. Fixings: on rafters №2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, on each rail line, drill the sheet at the corrugation crest with a step drill Ø12, and a pilot hole Ø7 into the rafter. Screw hanger bolt M10×200 (72 pcs) ≥ 70 mm into the rafter, fit the EPDM washer and sealing nut — compress the EPDM by 1/3. Around the hole — sealant. Set the adapter / L-bracket to the string line with the nuts, tighten to 15–20 N·m.
4. Rails: fix the rails to the brackets with T-bolt M8 (1 per fixing, 72 pcs), adjusting the bracket height so that the rails are in one plane.
5. Earth the array: bond the rails of each row to each other and to the rails of other rows with a 6 mm² Cu conductor via rail earthing clamps.
6. Make the cable penetration through the roof covering above the array: a penetration with an EPDM collar or a cable gland, sealant under the flashing.
7. Install the panels from bottom to top, starting from the gable.
8. Fix the cables to the frames and rails with stainless steel clips every 300–400 mm so that they do not lie on the roof covering or rub against its edge.
9. Install snow guards above the eaves below the array across the full width of 11 180 mm, fixed into the rafters.
10. Check the penetrations after the first rain (from the attic — for any traces of water).

The shared steps in full are on the section page

Common mistakes

• Drilling in the trough of the corrugation. Water runs there; drill only on the crest, with an EPDM washer and sealant.
• Fixing the bracket to the battens only. The calculation takes the hanger bolt into the rafter — that is what resists wind uplift.
• Tightening the sealing nut all the way. The EPDM washer is compressed only partly — the installation steps say how much.