Solar panel array larger than roof? Hang off the side or something?

[wantons0up]

I got a quote for a ground mount system, but we have been considering building a detached garage next to the house and thought, "Hey, let's put solar panels on the roof! Kill two birds!"

Well, the roof surface would only be about half the size we need for the 10 kW system we want. So, wondered what the best option is. Half on the roof, and then a smaller ground mount array? All on the roof with some sort of extension mount system where they protrude past the roofing surface? I don't know.

[HX_Guy]

Fire code setback rules most likely won't allow that, but that will depends from city to city on what's allowed.

Maybe also look at higher output panels like SunPower or LG and see if the there is a cost benefit vs splitting up the array in two.

[organic farmer]

Make a larger garage?

It is fairly common around here to see homes with an attached barn. So you dont have to go outside to milk, etc.

[Naptown]

There is an exception in the firecode for detached garages.

[inetdog]

Fire code setback rules most likely won't allow that, but that will depends from city to city on what's allowed.

Maybe also look at higher output panels like SunPower or LG and see if the there is a cost benefit vs splitting up the array in two.

If they apply to the garage, which might not need ventilation in case of a fire if the rafter space is open rather than an enclosed attic, then the setback rules will typically apply to the sloping edges and the top peak, not the lower edge of the roof. But that one edge would not allow much overhang before it intruded on the walking space next to the garage. A factor of two seems out of the question.

Now you might be able to design the garage with on open framework extension going above the peak of the roof for an area the size of the roof that already faces in the right direction. Or would that shade/block sight lines of windows in the main portion of the house?
Is there no chance of adding panels on the main house roof at the same time to make up the difference?

[wantons0up]

If they apply to the garage, which might not need ventilation in case of a fire if the rafter space is open rather than an enclosed attic, then the setback rules will typically apply to the sloping edges and the top peak, not the lower edge of the roof. But that one edge would not allow much overhang before it intruded on the walking space next to the garage. A factor of two seems out of the question.

Now you might be able to design the garage with on open framework extension going above the peak of the roof for an area the size of the roof that already faces in the right direction. Or would that shade/block sight lines of windows in the main portion of the house?
Is there no chance of adding panels on the main house roof at the same time to make up the difference?

OP here. A few things - this will be a freestanding detached garage. And I'm outside city limits, so that may help.

No chance of putting panels on the house. Complicated story, but that's where it is. Either on this garage, or ground mount.

[J.P.M.]

OP here. A few things - this will be a freestanding detached garage. And I'm outside city limits, so that may help.

No chance of putting panels on the house. Complicated story, but that's where it is. Either on this garage, or ground mount.

There are other jurisdictions besides cities. Just sayin'

Garage mounts may lessen the probability of injury or vandalism, and may be less expensive.

Add: Put big overhangs on the garage roof, or reduce the electric load, or both.

[JFinch57]

I got a quote for a ground mount system, but we have been considering building a detached garage next to the house and thought, "Hey, let's put solar panels on the roof! Kill two birds!"

Well, the roof surface would only be about half the size we need for the 10 kW system we want. So, wondered what the best option is. Half on the roof, and then a smaller ground mount array? All on the roof with some sort of extension mount system where they protrude past the roofing surface? I don't know.

Unless you're going to have an engineer certify the modified design I doubt that you will get it past your building department, no matter where you live (assuming it has to be inspected). How about a car port attached to the garage? The stability of the car port would be certified by the architect and you can use standard mounting systems.

[bcroe]

No chance of putting panels on the house. Complicated story,
but that's where it is. Either on this garage, or ground mount.

Ground mount avoids a lot of issues of roof mount systems. Bruce Roe

[organic farmer]

There are other jurisdictions besides cities. Just sayin' ...

Most of the USA [ie, the vast majority of square-miles] is other than urban.

Just saying.

Unless you're going to have an engineer certify the modified design I doubt that you will get it past your building department, no matter where you live (assuming it has to be inspected). How about a car port attached to the garage? The stability of the car port would be certified by the architect and you can use standard mounting systems.

Living in an Off-Grid Mecca as I do, I often forget that there are still people stuck in cities with such oppressive devices like 'building departments', or that require engineers certifying designs, or architects.

[foo1bar]

Most of the USA [ie, the vast majority of square-miles] is other than urban.

Just saying.

Living in an Off-Grid Mecca as I do, I often forget that there are still people stuck in cities with such oppressive devices like 'building departments', or that require engineers certifying designs, or architects.

Even in places where the nearest neighbors are >1/2 mile away there is often/usually an Authority Having Jurisdiction (AHJ). Some townships/counties may choose to not do permits or inspection, but many do.

[organic farmer]

Even in places where the nearest neighbors are >1/2 mile away there is often/usually an Authority Having Jurisdiction (AHJ).

I am not sure if you understand what 'often' or 'usually' mean. In my mind, those terms would imply more rather than less.

... Some townships/counties may choose to not do permits or inspection, but many do.

It requires a much higher tax-base to support having inspectors on salary.

Neither my town, nor my county; have the surplus revenue to hire any more useless bureaucrats.

My home building permit came with a 'Certificate of self-inspection and completion'. Since my town does not handle building permits, and my county does not, I went through the state for it.

How new construction is handled in my town, is identical to how it is done in over 52% of the townships on this state.

[foo1bar]

I am not sure if you understand what 'often' or 'usually' mean. In my mind, those terms would imply more rather than less.

...
My home building permit came with a 'Certificate of self-inspection and completion'. Since my town does not handle building permits, and my county does not, I went through the state for it.

How new construction is handled in my town, is identical to how it is done in over 52% of the townships on this state.

So even you have an AHJ - in your case it's the state.

It requires a much higher tax-base to support having inspectors on salary.

Neither my town, nor my county; have the surplus revenue to hire any more useless bureaucrats.

Often those departments aren't a significant extra burden.
They increase the tax base of the area (because there's documentation of any improvement).
The extra manpower needed is either supported by the additional income from permit fees or is negligible if few permits (one township I know of uses staff of the village adjacent to it for processing the permits - probably less than 1hr/week of the secretrarial person is spent on it.)

[pleppik]

I got a quote for a ground mount system, but we have been considering building a detached garage next to the house and thought, "Hey, let's put solar panels on the roof! Kill two birds!"

Well, the roof surface would only be about half the size we need for the 10 kW system we want. So, wondered what the best option is. Half on the roof, and then a smaller ground mount array? All on the roof with some sort of extension mount system where they protrude past the roofing surface? I don't know.

Here's a random thought: since this is new construction, have you considered building a garage with a mono-pitched roof? That way you can get twice as much roof area optimally angled for a solar array.

(I'm assuming that what you planned to build was a garage with a more conventional roof.)

[J.P.M.]

Most of the USA [ie, the vast majority of square-miles] is other than urban.

Just saying.
Living in an Off-Grid Mecca as I do, I often forget that there are still people stuck in cities with such oppressive devices like 'building departments', or that require engineers certifying designs, or architects.

Yea, but there's not much need for building regulations or inspectors on unimproved land.

And I'd add that about 80% or so of the U.S. population lives in urban or suburban areas and are therefore in the un vast minority of square miles. I'd wager that most of those folks probably fall under some jurisdiction and subject to those nasty gobment intrusions.