How to Mount Solar Panels on a Yero or Long-Span Metal Roof in the Philippines

On a Philippine yero (corrugated) or long-span metal roof, rigid solar panels are normally mounted on aluminium rails fixed through the high ribs of the roof sheet into the purlins underneath, with end clamps and mid clamps holding the panel frames to the rails, and every roof penetration sealed against leaks. A solar rail and clamp kit for metal roofs, 30mm end clamps (for 30mm-thick frames) and an MC4 spanner cover the basic hardware. Because none of these kits publish a wind or load rating, a permanent typhoon-season array should have its roof structure and fixings checked by a qualified engineer.

This guide explains each part, how they fit together, how to stop leaks, and where DIY stops and a professional has to take over. It assumes rigid, framed panels. If you’re still choosing between flexible and rigid, read our flexible vs rigid panels guide first.

Know your roof before you buy anything

Go up (safely, or ask someone who does roof work) and look at three things:

1. The roof sheet profile. Traditional yero is corrugated, with rounded waves. Long-span roofing has trapezoidal ribs with flat pans between them. Mounting hardware is often made for one profile or the other, so check the listing photos.
2. The purlins. These are the horizontal steel C-sections or timber members the roof sheet is screwed to. You can usually see them from inside the ceiling space or follow the line of existing roofing screws. Note how far apart they are and what they’re made of. Your rails will be fixed into these, so the spacing decides where the rail fixings go.
3. The condition. Rust, loose screws, sagging sheets or old leaks need fixing first. Putting panels over a weak or rusty roof hides the problem for years and makes it harder to repair later.

If the roof sheets or purlins look thin, rusted or uneven, stop and get a structural or civil engineer to look before adding any weight. Panels also add wind load: in a typhoon, wind can push up under the array and try to lift it.

The parts and what each one does

Rails

Rails are long aluminium channels that run across the roof, usually at right angles to the purlins. The panels sit on top of the rails, which spreads their weight across several fixing points and lifts them off the roof so air can flow underneath. That air gap keeps the panels cooler, and solar panels produce less power when they’re hot.

The solar rail and clamp kit on Shopee (also on Lazada) is sold for metal roofs. The listing doesn’t publish a load or wind rating, and kit contents vary between sellers and variants. Before you order, check:

• Rail length per piece and how many pieces you get
• Whether rail splices (joiners) are included if you need longer runs
• How many roof attachments (L-feet, hooks or hanger bolts) come with it
• How many end clamps and mid clamps are included, and what frame thickness they fit
• Whether it comes with sealing washers or rubber pads for roof penetrations

If something’s missing, buy it separately rather than improvising.

Roof attachments: L-feet and hanger bolts

The rails need to be fixed to the roof structure through the roof sheet. On metal roofs, two common ways are:

• L-feet with self-drilling screws into the purlin through the crest of the rib.
• Hanger bolts: a bolt with a wood or self-tapping screw thread on one end and a machine thread on the other. The screw end goes through the roof sheet into the purlin; the machine-thread end sticks up and holds an L-bracket or the rail with a nut. A rubber seal sits under the nut at the roof surface.

Either way, the key point is that the fixing has to grip the purlin, not just the roof sheet. A screw that goes only into the thin sheet can pull out in strong wind.

End clamps

End clamps hold the outer edge of the first and last panel in each row. They hook over the panel frame and bolt down into the rail.

Clamp height must match frame thickness. Here is what the listings say about the frames of the panels we link to:

These sizes come from the marketplace listings. Measure the frame of the panel you receive with a ruler before ordering clamps. A clamp that’s too tall won’t grip; one that’s too short won’t fit over the frame.

Mid clamps

Mid clamps sit between two panels and hold both frames at once. Most rail kits include them. Like end clamps, they’re sized for a frame thickness, or have an adjustable design. If your kit doesn’t say which thicknesses its mid clamps fit, ask the seller.

Z-brackets: for single small panels

Z-brackets (4 pcs) on Shopee are Z-shaped metal pieces. One leg bolts to the panel frame and the other screws to the surface. They’re a simple, low-cost way to fix one small panel to a flat surface, a wall, a frame, a shed roof or a vehicle. They don’t use rails and leave only a small gap under the panel.

For a single 60W–100W panel charging a small battery or power station, Z-brackets can be enough. For several panels or larger 200W panels on a house roof, rails are the more common approach. The listing doesn’t publish a load rating, so use them for small, light panels and fix them into solid structure.

Tools that make the job easier

• MC4 connector spanners (pair) on Shopee. Most rigid panels use MC4 plugs (the PowMr and Flowatt rigid listings say “MC4 compatible”). MC4 plugs lock together and are hard to separate by hand. Pulling on the cable damages them. The spanner releases the lock properly and tightens the cable gland on the back so water can’t get in.
• Solar panel angle guide on Shopee. On a pitched roof, panels on rails follow the roof’s angle. The angle guide shows you the actual tilt, which is useful when estimating output or when setting up a tilted frame on a flat concrete roof. Some tilt also helps rain wash off dust.
• A cordless drill/driver, the right bits, a tape measure, a chalk line, a torque wrench if the kit specifies torque values, and a safety harness for any roof work.

Step by step: how a rail-mounted array goes on a metal roof

This is a description of the usual sequence, so you can follow what an installer is doing or plan a small, non-wired setup. It isn’t a substitute for the instructions that come with your kit.

1. Plan the layout on paper. Measure the roof area and the panels. Leave clear space at the roof edges and ridge, where wind forces are usually strongest. Mark where the purlins are.
2. Mark the attachment points. Snap chalk lines along the purlins. Each rail needs attachments at regular intervals along its length, into the purlins. Follow the kit instructions for spacing. If none is given, ask the seller or an engineer rather than guessing.
3. Drill and fix through the crest. Fix through the high rib of the sheet, not the valley. Water runs down the valleys every time it rains.
4. Seal every hole. Use the rubber sealing washer or pad supplied, plus a sealant compatible with your roof sheet (more on this below).
5. Mount the rails. Bolt the rails to the L-feet or hanger bolts. Check that they’re straight and level with each other, using a string line.
6. Lay the panels and fit the clamps. Start with an end clamp on the first panel, then mid clamps between panels, then an end clamp on the last. Tighten to the kit’s stated torque.
7. Manage the cables. Clip the panel cables to the rails so they don’t rest on the hot roof or sit in water. Leave drip loops so water runs off before reaching connectors.
8. Leave the electrical connection to the electrician. Plugging panels together with MC4 connectors is simple, but connecting the array to a charge controller, inverter or your house wiring is electrical work. See the safety section below.

Sealing against leaks during the rainy season

A leak from a badly sealed roof screw can soak the ceiling, rot the purlins and short out wiring. During the habagat and typhoon season, rain can be driven sideways and upward under laps, so sealing matters even more.

• Fix through the crest, never the valley. This is the most important rule on corrugated and long-span roofs.
• Use a sealing washer (a metal washer with a bonded rubber layer) under every screw head or nut, the same kind used on regular roofing screws.
• Don’t over-tighten. Squashing the rubber washer flat or dimpling the roof sheet creates a gap where water gets in. Tighten until the washer just bulges slightly.
• Use a compatible sealant. Ask the hardware store for a sealant meant for metal roofing, and check that it won’t react with your roof’s coating.
• Avoid mixing metals where you can. Stainless steel or coated fasteners on a galvanised roof sheet are common, but avoid leaving copper or bare steel shavings on the roof. Sweep away drilling swarf (the metal shavings) straight away, because it rusts and stains the roof.
• Check after the first heavy rain. Go into the ceiling space with a torch and look for drips or wet marks under each fixing.

Typhoon considerations

Every year, typhoons test rooftop equipment across the country. Panels on a roof catch wind from above and below. Strong gusts can lift a poorly fixed array, rip roof sheets, or turn a loose panel into a dangerous flying object.

General measures that reduce the risk:

• Fix into purlins, not just sheets. Repeat this to anyone working on your roof.
• Use enough attachments. More fixing points along each rail spread the uplift force.
• Keep away from roof edges, corners and the ridge, where wind forces tend to be higher.
• Keep the array low. Tilting panels up steeply on a pitched metal roof increases the wind they catch.
• Inspect before and after typhoon season. Check every clamp and bolt for looseness and rust, and look for lifted roof sheets.
• Bring portable panels inside when PAGASA raises a wind signal.

We don’t publish wind-speed or pull-out ratings for any of the kits linked here, because none of the listings publish them. If you want a permanent array to stay up through a strong typhoon, have a structural or civil engineer confirm the roof framing, the fixings and their spacing.

When a professional is required

Structural. If your roof is old, rusted, built from thin sheets, or you’re adding several large panels, ask a civil or structural engineer to check that the purlins and roof framing can take the extra weight and wind load. Some LGUs may ask for structural documents for rooftop work, so check with your local building official.

Electrical. A portable panel plugged into a power station is a plug-and-play setup you can do yourself following the manual. Anything wired to the house, a breaker panel, the roof or the grid needs a licensed electrician and an LGU electrical permit. RA 7920 Sec. 34 says electrical plans must be “signed and sealed by a professional electrical engineer”, that a construction permit must be secured first, and that the work must follow the Philippine Electrical Code under the supervision of a professional electrical engineer, registered electrical engineer or registered master electrician. If you plan to export power, the net metering process also applies. Meralco notes that even systems meant only for your own use should be reported to them.

Working at height. Metal roofs are slippery when wet and dangerously hot at midday. If you aren’t used to roof work, don’t go up. Many falls happen during “just a quick look”.

For the full process from quotes to switch-on with a contractor, see our residential solar installation guide. To size the array first, see how many solar panels a Philippine home needs or use the solar system size calculator.

Rails or Z-brackets? A quick decision table

What to buy

• Rail and clamp kit: on Shopee or on Lazada. Check rail length, number of roof attachments, number of clamps and which frame thickness they fit.
• 30mm end clamps on Shopee: only if your panel frame is 30mm thick. Two per row.
• Z-brackets (4 pcs) on Shopee: for a single small panel.
• Solar panel angle guide on Shopee: to check tilt.
• MC4 connector spanners on Shopee: to connect and disconnect MC4 plugs without damage.
• From the hardware store: sealing washers, a metal-roof sealant, stainless or coated fasteners, cable clips.
• Panels with a known frame size: PowMr 200W rigid or Flowatt 200W rigid (30mm frames per listing). Their electrical specs aren’t published, so read the label before any wiring.

Prices change daily, so check today’s price on each listing.

Bottom line

A safe metal-roof mount comes down to four things: rails fixed into the purlins, clamps that match your panel’s frame thickness, sealed fixings through the high rib, and a structure that can handle typhoon wind. The mounting hardware linked here covers the basics but publishes no load ratings, so for a permanent array, get a structural check, and leave all wiring to a licensed electrician.