Mounting solar panels on clay and concrete tile roofs

Fixings and rails

• Clay tile: Roof hook (adjustable) + 2 screws Ø8 → rafters. The hook must not press on the tile — notch the groove, gap 3–5 mm. Keep spare tiles.

Check before installation

• The rafter height relative to the batten. The hook adjusts in height, and if the rafter sits lower than the batten a board goes under the hook.
• Whether there are spare tiles of the same profile: some tiles under the hooks will be trimmed.
• The rafter spacing. The hook is fixed to the rafter with two or three screws in pilot holes, so the spacing decides where the hooks go.

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: above rafters №2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 remove the tiles along the rail lines. Screw down the hook (72 pcs) with 2–3 screws 8×80 (pilot hole Ø5, ≥ 60 mm into the rafter); if the rafter is lower than the batten — pack it with a 40 mm board. Adjust the hook height to the string line. Trim the lower tile under the hook with an angle grinder so that the hook has a 3–5 mm clearance and does not press on it. Put the tiles back in place. Check: when the hook is pressed, the tile takes no load.
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

• Laying the tile straight onto the hook without trimming. Under snow the hook presses on it and it cracks.
• Fixing the hook to the batten, not the rafter. If the rafter sits lower than the batten, a board goes under the hook.
• Not checking the result. Press on the mounted hook: the tile under it must take no load.