Solar panel height off roof

Tilted panels have never been too popular. After climbing the roof to tilt them on and off, and doing this several times, you'll become less enthusiastic about it. In summer 3 flat panels will harvest more than 2 perfectly tilted would, and with today's prices adding one more panel is a no-brainer. I've seen some very elegant tilting solutions but you still have to climb 11 ft ladder, walk on the roof and climb down - no matter how good is your design.

I designed my 2*250W panels to be tilted in 2 directions, but by the time I've installed and tested the 1st panel, I realized that didn't need any tilt.

Pins are popular on tilted panels, and they will keep panels less tight than bolts with locknuts on permanently flat panels.

Racking, brackets and anchor screws in the roof become more complicated (and you'll need more of them), if you go for tilted.

Keeping panels as close to the roof as possible - yes, absolutely. Tilting has nothing to do with this. 0.75"-1" should still be left under the frame. Raising panels to clear obstacles - you still might have to do this whether they can be tilted or not. People raise their panels to clear obstacles, not to get more light.

With 1" under the frame the panel surface will be 2.5" above the roof, at this point the only thing that might cast shade is the roof A/C, and raising a panel THAT high is not practical. Keep at least 12-18" from the A/C. If one corner of one of your panels will be shaded by A/C for some time on some campsites - no big deal.

Cut a cardboard template up to scale and move it around on the roof, put a few pieces of 2x4 underneath to get an idea how much shading you'll get with a 1" clearance. 2x4 is 1.5", panel frame is also 1.5", so the cardboard will imitate the panel surface.

Make a scale drawing of your roof and scale cutouts of different sized panels and see what fits where. Then consider mounting, tilting, wiring, controller, costs and rooftop shadows.

In my case 3x250W panels was a much better fit than 5x150W panels.

First.. Depending on how things are mounted optical illusions are a fact of life.

Second. I would want my solar panels as close to the roof as possible, WHY.. Low Overhang (Bridge, Overpass, Tree limb) the closer to the roof the less chance of leaving them behind and a hole where they ripped out.

Why raise them WHEN PARKED.. Well it is best if they are not shadowed (that is in the shadow of something) so you might wish to position them on the sunny side of _____ (everything) this is best done by using a flexible mount system,,,

Basically it is a set of removable pin hinges one one each side (Driver's curb) and supports so you can slant the panels at the optimum angle for where you are.. you might even want four sided hinges for that (front and rear as well) Just in cuss you are parked as I am.. Facing south.

NOTE optimum angle depends on where you are as well.. In Michigan it is a tad higher than in say Texas.

12V panels = more flexibility of layout, though more holes and mounting brackets and higher cost of panels. Worth considering on a small roof like truck camper. Either PWM or MPPT can be used then, depends on the system and user's priorities.

On a bigger rig, say 23ft trailer or longer, it's easier to use big 24V panels and stay clear of A/C and/or lift panels few more inches to clear small structures.

Old thread with roof rack that I mentioned earlier... Yep, about 5" to the frame bottom. This is a distant past of solar panels, they were expensive and people didn't install more than 200-300W. My point was - you lift panels to clear roof structures other than A/C. From A/C you should stay clear.

Panels can be mounted higher as needed but from a practical standpoint roof equipment like A/Cs should likely determine the maximum.

The primary reason I raised mine was to allow use of the larger 24V panels which needed to clear 2 roof items.

But why not just use smaller 12V panels? For about 500W or so the cost of 24V panels per watt with a MPPT controller was only $100 more than equivalent wattage with a PWM controller and that was my 2014 prices. The price per watt for the larger panels has dropped since then favoring MPPT controllers.

New solar installs should consider costs, power needs and future power needs. Existing solar installations have different considerations and there are many very good 12V panel systems on RVs.

FW wrote:
what would be the max height you could mount solar panels? I thought I saw a motorhome going in the opposite direction in SoCal with panels raised over his rear air conditioner.

If the wind - either from weather or driving - is under 5 MPH, sky is the limit :)

For heat dissipation you want at least 1" under the frame bottom.

One of my panels is lifted 2.5" frame to roof, to clear the plumbing vent - the actual panel bottom is ~3.5" from the roof. Another panel is sitting 1" lower.

Mostly, people lift panels to clear obstacles - not the shade. The very first install on that famous "list" by Sleepy is on the motorhome roof rack, about 5" high as I recall. A/C is the tallest thing on the roof, stay 12"-18" clear from it.

"Shadows can kill solar performance" but there are options. I've posted several results using MPPT and 24V panels with bypass diodes. I get charging with leafy shadows when PWM won't.

My panels are about 4-6" off of the roof and sloped 4 degrees. The fan you saw is a fantastic fan that stops opening when it hits a limb or in my case the panel.

Shadows kill solar performance and my panels which are mounted higher eliminate shadows. Not everyone wants to raise the panels but I wanted to maximize my solar. Others have done the same and I talked to everyone I could with raised panels. Done correctly there is no downsize in spite of some bias on this board raising panels.

front towards the front of mh. that is the a/c unit

For tlaffourtit: Are your panels on a box, or you just blocked the lead edge? What is the black boxy item in the picture?