Installing Solar Panels with Raked Ceilings: Challenges and Solutions

Spot the screws poking through…

They say that happiness is directly proportional to ceiling height.

Having grown up in a substantial c.1875 stone house, with ceilings closer to 4 metres than the standard suburban 2.4 metres, I can attest to the extra space offering some comfort – even if it’s just lower temperatures during hot summers.

I guess it’s not surprising then that the seventies and eighties saw more than a few places built with raked (or cathedral) ceilings to make them feel less cramped. Like mission brown colour schemes, oil-burning heaters and olive green roofing, raked ceilings have faded. Trends in building now favour square set corners, ducted air conditioning and appliance white everywhere, probably because it’s cheaper.

Why Do Solar Installers Hate Raked Ceilings?

I’ll try to explain the reluctance of some solar installers to tackle pitched or flat roofs with vaulted ceilings and exposed structure. It need not be a deal breaker and in some instances, a minor ceiling repair will suffice.

I don’t think I’ve ever encountered a roof I can’t put solar panels on, however that might have been because I was pretty willing to push what I could do, and the framing we had to use at Solar Depot was very adaptable. It gave you choices of where to put screws that weren’t dictated by panel placement.

With that said, raked ceilings with exposed rafters can be a pain in the backside, no matter what frame you use.  Not just because wiring often has to be run externally in conduit, which can be aesthetically challenging. The real issue is raked ceilings are very thin structures.

The “unventilated space” leaves precious little room for insulation and no room for error when driving screws into the rafters. image credit National Construction Code

While construction detail varies, generally the rafters are exposed as a feature, so the ceiling goes on top and then the battens/purlins are fitted to carry the roof cladding. When you’re on top of the roof, finding the right place to put substantial fixings in can be difficult.

Despite my best efforts, I will admit I have once driven screws through the roof and embarrassingly had a row of them come out through the lounge room ceiling. In that instance, we got away with cutting them off flush and putting a dab of white paint on to cover up the mistake, but even that was a mission.

This delightful mess shows an original 1970’s feature that has been covered up. The gold air conditioning duct now sits on top of a conventional flat ceiling. However, with some wall missing, you can see highlighted the real structure above the decorative raked ceiling.

Some installers just put raked ceilings in the too-hard basket along with asbestos, steep pitch, tin tiles, slate, and retired electrical engineers. A good solar installer will still be able to cope with any of these challenges, but they won’t be found at the cheap end of the market.

It’s also worth mentioning that some raked ceilings aren’t what they appear. You may have a conventional roof with conventional rafters supporting standard purlins/battens, which makes installation easy enough because the actual ceiling is below the rafters and has decorative “rafters” fixed on the very bottom.

Mid-century modern with cutting-edge white paint. This certainly isn’t a vaulted ceiling in the Sistine Chapel sense. Image Credit: Solar Depot

Have A Raked Ceiling? I Recommend Two Things:

• First, a check, measure and quote for solar panels from an actual installer who can kick tiles or unscrew roof sheets to work out precisely how the installation can be done on your house.
• Second, consider insulation along with fitting solar power.

Many houses with raked ceilings have terrible thermal performance because there simply isn’t much of a cavity to install bulk fill insulation, or what has been installed is old, compressed, collapsed or badly fitted. My understanding is that if gaps in coverage are as little as 5%, the reduction in overall thermal performance can mean your R2.5 insulation will only perform like R1.5.

Strammit straw ceilings, is there anything more 70s? They actually aren’t bad insulation and easily hide errant screws. Image Credit: My Mum

Make Significant Gains In Comfort And Running Costs

As well as making solar much more feasible is if you undertake some renovations that include insulation, and even a new ceiling that conceals the rafters. The plan, if you have a very skinny roof profile, would be to install solar panels and run wiring for the array and maybe wiring for new lights inside the house.

Next, put bulk fill insulation batts between the rafters and/or sheet underneath them with foilboard, then finally, a smooth new gyprock ceiling and LED lights. Preferably NOT downlights that require you to put holes, that leak energy, through the new ceiling.

DIY retrofitting insulation under an existing raked ceiling. Image Credit: Renew Magazine

Not only will the solar panels provide an energy input you can use for heating and cooling, but insulation will minimise energy loss from the building envelope, so there’s a triple benefit of increased efficiency, greater comfort and much lower energy bills.

While it may be hard to quantify exactly how much this will save without a comprehensive energy audit, I’m pretty sure you could obtain a “green loan” on very attractive terms to spread the financial hit over a few years.

If you have a tile roof, and really want to go the whole hog, I would really encourage you to put the broken masonry in the bin and install steel roofing. Having been involved in a job that replaced 16 tons of tiles with 1.25 tons of iron, I can assure you the house will thank you for removing the load. It’s much lighter, so the eaves won’t sag and cause the gutters to pool water, plus it gives you even more opportunity to insulate; possibly without needing a new ceiling.

This recently replaced iron roof has new “blanket” insulation fitted. The DC solar wiring in the white conduit needed to be drilled through the timbers because the roof has very little depth. Image Credit: Solar Depot.

You Always Look For A Shady Car Park In Summer

What many don’t appreciate is that even without insulating your roof, summer can be made much more bearable by simply parking the house in the shade. A customer of mine noticed this before they ever had a solar power-reduced bill. The flat roof beach shack was cooler inside because with a 10kW solar system, it now had around 65 square metres of roof that wasn’t in the blazing sun.

Seek Out Good Solar Installers

If you are looking for cheap solar systems you’ll get cheap results. Properly executed systems will prove most inexpensive in the long term, so don’t take no for an answer. There are good installers willing to work on bespoke houses, so with some help from SolarQuotes you can keep your happiness and your raked ceiling high and rising.