Solar panels and your roof, and what each kind changes
Almost every roof around here can carry an array. The question worth asking is not whether yours can, it is what yours changes about the job: how the panels are fixed, how long the crew is up there, and what has to be made good when they come down.
Most of what a search turns up for this was written for asphalt shingle, which is a roof almost nobody in Pampanga has. So this is the version for the roofs that are actually on the houses and warehouses we work on.
The roofs around here, and what each one means for the fixing
The roofing is rarely the deciding factor. What is under it usually is.
- Corrugated or rib-type GI sheet The usual one, on houses and on most small warehouses
- Panels clamp to the ribs or bolt through into the purlins underneath, so the steel beneath the sheet is what carries them and its spacing is what decides the fixing. A surveyor spends the visit up there with the purlins.
- Standing seam metal Newer builds and some commercial roofs
- The friendliest roof there is. Clamps grip the seam itself, so nothing has to be drilled through the weatherproofing at all.
- Concrete deck Flat roofs, roof decks, many commercial buildings
- No pitch to work with, so the array sits on a frame that is set to an angle. That frame adds weight and it has to be fixed or ballasted without breaking the waterproofing, which is the thing that goes wrong on a flat roof.
- Clay or concrete tile Less common here than in the guides written elsewhere
- Tiles come up, hooks go onto the battens, tiles go back. It is slower and some tiles break in the process, so the count of spares is part of the conversation before anybody starts.
- Asphalt shingle Rare here, and it is what most guides online assume
- Worth naming only because almost every article ranking for this question is written for it. If you are reading advice about flashing and shingle penetrations, it was not written for your roof.
What somebody is actually looking at on the survey
Five things, and only one of them is visible from the ground. None of them needs you to measure anything yourself; they are here because each one is a reason a job gets moved, and finding out early is the cheap version.
- What is under the sheet
- Purlin size, spacing and condition carry the array. This is the single thing that decides whether a roof takes panels as it stands, and it cannot be judged from a photo of the outside.
- Which way the slope faces
- South-facing is the textbook answer and east and west both work here, with the output spread differently across the day. A roof with two usable slopes is often better than one, because the morning and afternoon do not arrive together.
- What shades it, and when
- A neighbour’s wall, a water tank, a mango tree, the new second storey next door. Shade that only arrives at four in the afternoon still costs you four in the afternoon, every day.
- How old the roof is
- The panels will still be working long after a tired GI sheet has stopped. If the roof is near the end of its life, the roof goes first, because taking an array off and putting it back is paid for twice.
- How anybody gets up there
- Access decides the working method and the safety arrangements, and on a tight lot it occasionally decides whether the job is done from the roof or from a lift.
If the roof is tired, the roof goes first
An array outlives the sheet it is bolted to. Put panels on a roof that has a few years left and you pay to take them off, pay for the roofing, then pay to put them back, which is the one avoidable cost in this whole business.
So it gets said at the survey, before anything is ordered. It is a slower sale and it is the right advice, and it is the reason the survey spends its time on the underside of a roof rather than admiring the view.
What a home installation involves
What people ask about panels and roofs
What type of roof is best for solar panels?
Standing seam metal, because the clamps grip the seam and nothing is drilled through the weatherproofing. After that a corrugated or rib-type GI sheet roof in sound condition, which is what most houses around here have and which takes panels perfectly well.
Best is not the useful question though. Almost every roof here can carry an array; what changes between them is the mounting method, the time on site and what has to be made good afterwards.
Can solar panels be installed on any roof?
Nearly any, but the answer turns on the frame rather than the roofing. Panels are carried by the purlins or the slab under the surface, so a roof that looks fine and sits on tired steel is the one that gives trouble.
The two that genuinely stop a job are a roof at the end of its life and a roof nobody can safely work on. Both are cheaper to find out about before anything is ordered.
Do solar panels damage the roof?
Not when the penetrations are made and sealed properly, and on a standing seam roof there are no penetrations at all. The array also shades the sheet under it from the sun, which the roof does not mind.
What does cause damage is fixing into something that was not meant to carry a load, which is why the survey spends its time underneath rather than on top.
Is a solar type roof the same as a roof with solar panels?
No, and this catches people out. A solar type roof is a house design, a single-slope shed roof, and it has nothing to do with generating electricity. You can put panels on one, in the same way you can put panels on a gable roof.
If you came here looking for the roof design, this page is about the panels. If you came here about panels, the term is worth knowing because it is what most of the search results for it are about.
How long do solar panels last on a roof?
Longer than people expect, and usually longer than the roof under them. That is the fact that matters when deciding the order of work: a roof replaced after the array is up costs the removal and the refit on top of the roofing.
We will say plainly at the survey if we think the roof should come first. It is a slower sale and it is the right advice.
Send a photo of the roof and the town it is in
A picture of the roof and the outside of the house tells us most of it, and the rest comes from the survey. You will get a written answer with what your roof changes about the job.
Tell us the property and what you are trying to cut, and you will get a written answer with a size and a next step. No visit is booked and nothing is charged for asking.