Driving on Sunshine

[gg_got_a_tesla]

I would strongly recommend the installation of a steel roof before you install solar. The roof should last as long (fifty years) as the life of the solar system without significant repair or replacement work.

Thanks, Richard. Unfortunately, my house is in a subdivision where the HOA is strict about all exterior architectural choices including roofing and siding materials, colors and even garage door styles. In fact, I may have a little bit of a battle on my hands to get the solar system approved as I'd be the first one in my 105-home community to go solar but, I'm ready to read the riot (aka Calif. Solar Rights) act to them.

 

[green1]

I would strongly recommend the installation of a steel roof before you install solar. The roof should last as long (fifty years) as the life of the solar system without significant repair or replacement work.

Better yet, look in to solar roofing panels, you can make the roof out of solar panels and kill 2 birds with one stone so to speak. they make both solar shingles (designed to match in with asphalt shingles as on the roof pictured above, or standing seam metal versions to fit in with a steel roof.

If you're replacing both at once anyway, look to see if it makes sense to avoid the duplication and go for a 2-in-1 solution.

 

[bollar]

This is the exact same kind of roofing material that I have. I do need a new roof this year and am contemplating solar at the same time.

Any details that you can share on the nature of solar installation on such a roof?

Installing PV on asphalt shingles is straightforward. Typically, metal flashing is slid under a course of shingles and secured to the underlying rafter using a lag bolt. The racking is attached to the lag bolt with an L footing and the roof penetrations are sealed with a compound like Chemlink. Typically this type of installation has a 25 year manufacturer's warranty.

If you want to see step-by-step pictures, I'd suggest you visit a racking site, like Ironridge.

 

[RichardC]

Thanks, Richard. Unfortunately, my house is in a subdivision where the HOA is strict about all exterior architectural choices including roofing and siding materials, colors and even garage door styles. In fact, I may have a little bit of a battle on my hands to get the solar system approved as I'd be the first one in my 105-home community to go solar but, I'm ready to read the riot (aka Calif. Solar Rights) act to them.

As reflected in the following pictures, steel roofing comes in a wide variety of forms and colours (we went for a cedar shake colour and look).

 

[nwdiver]

As reflected in the following pictures, steel roofing comes in a wide variety of forms and colours (we went for a cedar shake colour and look).

What mounting system is that?

 

[RichardC]

What mounting system is that?

It's been a few years, but I believe that the entire rooftop system (with the exception of the first layer of aluminum channel on the roof) was from SunPower.

 

[green1]

As reflected in the following pictures, steel roofing comes in a wide variety of forms and colours (we went for a cedar shake colour and look).

That looks like exactly the same roofing material that I have. I'm really curious as to how they handled attachment of the racking to that roof, do you happen to have any close-ups of the mounting hardware where it connects to the roof? or know exactly what they used?

The last thing I want to do is add a leak to my otherwise permanent roof...

 

[RichardC]

That looks like exactly the same roofing material that I have. I'm really curious as to how they handled attachment of the racking to that roof, do you happen to have any close-ups of the mounting hardware where it connects to the roof? or know exactly what they used?

The last thing I want to do is add a leak to my otherwise permanent roof...

We used 6 or 8 inch stainless steel lag bolts through the 2 X 2 inch at the front of each row of steel roof shingles into the underlying roof trusses. All sealed in high quality silicone. Also the roof was completely covered with ice and water shield so that any water that might get through the roof would get caught at that level and carried down to the eavestroughs (the latter was probably overkill, but I wanted to leave nothing to chance).

Five years in, so far so good - Touch Wood!

 

[green1]

We used 6 or 8 inch stainless steel lag bolts through the 2 X 2 inch at the front of each row of steel roof shingles into the underlying roof trusses. All sealed in high quality silicone. Also the roof was completely covered with ice and water shield so that any water that might get through the roof would get caught at that level and carried down to the eavestroughs (the latter was probably overkill, but I wanted to leave nothing to chance).

Five years in, so far so good - Touch Wood!

That was roughly my plan... though 6-8"? wow... I was planning on 3"... I'm a little concerned that the silicone is really only rated for about 10 years though, and the roof for forever. The advantage on the asphalt roofs is that the mounting hardware is under the shingle, letting water run over it, and not down the screws, but of course the asphalt is only a 10-15 year roof. (I wouldn't want to go through a roof replacement AFTER the solar is installed, that could be a real pain...)

 

[nwdiver]

It's been a few years, but I believe that the entire rooftop system (with the exception of the first layer of aluminum channel on the roof) was from SunPower.

Hmmm... I've NEVER seen 7 rails used for 6 rows of panels... it's usually 12 rails... neat.

 

[RichardC]

That was roughly my plan... though 6-8"? wow... I was planning on 3"... I'm a little concerned that the silicone is really only rated for about 10 years though, and the roof for forever. The advantage on the asphalt roofs is that the mounting hardware is under the shingle, letting water run over it, and not down the screws, but of course the asphalt is only a 10-15 year roof. (I wouldn't want to go through a roof replacement AFTER the solar is installed, that could be a real pain...)

The silicone is beneath the aluminum rail and covers a substantial area between the rail and the steel roof. Since it is not exposed to air or ultraviolet light, and there should be absolutely no movement between the parts, it should be reasonably durable. There is also minimal water on the roof as the panels extend to the top of the roof, the clamping strips close the gaps between the panels, and the rails run vertically on a 9/12 slope roof. To be clear the lag bolt path goes through a washer and the aluminum rail (where it is sealed in silicone), through the steel roof, through the 2 X 2 inch strap used to mount the steel roof, through the ice and water shield, and then into the underlying roof structure. I would hope that any water that might get through the steel roof would run off the 2 X 2 strap and down the ice and water shield to the eavestrough.

At least that is the theory!

 

[Electricfan]

I'm producing!! Got a cool sticker on my meter box!

 

[RichardC]

Congratulations! I love the little solar panels on your roof vents (it looks as though you have solar panels to drive fans to cool the solar panels).

 

[Electricfan]

Congratulations! I love the little solar panels on your roof vents (it looks as though you have solar panels to drive fans to cool the solar panels).

Yes, got them about 6 years ago - they're attic exhuast fans - nothing to do with my solar array. Bad thing is I need to replace the motors (the panels produce DC power and connect directly to DC motors on the fans) - they're all running very slowly now. But I guess that's why our cars have AC motors instead of DC - longer lasting...

 

[Electricfan]

Today its mostly cloudy outside, but the sun is peaking through occasionally. When it does, EVEN with my house's AC unit running, I'm exporting power to the grid! Man this is fun! In the picture below, the little arrow points to the left - means I'm exporting. It points to the right when I'm importing. It shows I've exported 9kwh so far. My system is sized so small that I won't be exporting much I don't think, but it should offset most of my usage. I'm thinking of signing up for the electric plan where power is free after 9pm, until 6am in the morning. I can charge the car and do all my laundry in that window quite easily. But the high rate in the day may kill me. We'll have to see.

 

[miimura]

Interesting. Are you sure it's not net 9kWh from the grid? PG&E Net Energy Meters read 50,000 kWh when new, presumably so they're not likely to show negative readings.

 

[Electricfan]

Interesting. Are you sure it's not net 9kWh from the grid? PG&E Net Energy Meters read 50,000 kWh when new, presumably so they're not likely to show negative readings.

The meter shows two kwh numbers - the 029 value shown above is my exported kwh, and the 01H value below is my total usage. At this point I've now exported over 41kwh. Its been nothing but partly to mostly cloudy since I installed my system dammit, so I am in suspense about what its going to do on a sunny day.

 

[Electricfan]

I left the Tesla at home today and drove my Volt to work. I set the charge to start at 11AM. So right now my Model S is drinking sunshine straight from my solar panels. Take that fossil fuels!

 

[derekt75]

I left the Tesla at home today and drove my Volt to work. I set the charge to start at 11AM. So right now my Model S is drinking sunshine straight from my solar panels. Take that fossil fuels!

Why would you do that instead of charging at night?
Is your solar system not grid tied?
Is the price per kWh the same at mid-day as it is at 1 am?
Even if it is, I think it's better for the environment for grid usage to be lower during the day and higher at night; the flatter the grid's energy usage, the better.

 

[green1]

Can't speak for his situation, but where I live the electricity you send back to the grid is worth only half of the value of the electricity that you get from the grid. Anything you can do to use your own electricity instead of the grid's saves you a substantial amount.