New roof and photovoltaic panels

[Nosmo King]

This spring, two big projects here at my home, the Pimplebutt Estate, will be replacing the existing (and failing) asphalt shingle roof with a standing seam steel roof (rare in these parts), and installing photovoltaic solar panels.

Anyone here have any experience with projects like these? Any tips?

I'd really appreciate your input.

 

[slackjawed]

I have some experience with alternative energy. I designed and installed (and lived) in a house 7 miles from the nearest power lines. That is very different from what you are discussing here. Solar panels have inherent problems that you will not hear from the industry, but those problems manifest themselves to a greater degree when they are used as stand-alone power supplies rather than when they are used in conjunction with the conventional power grid.
I suppose I should back out of here and just say, yes, I have practical experience with alternative energy installations, both personal and commercial applications.
If I can answer your questions, I will be glad to.

 

[Nosmo King]

I am going to use the PV panels as supplemental power. I could never generate enough solar power living here in the Pittsburgh area.

My roofer suggested using solar panels which adhere directly to the steel roof panels. The southern exposure of the roof faces my neighbor in the back, the main entrance to the house is on the north side. Solar panels would be invisible from the street.

I'm skeptical about this system. One of the reasons, besides longevity, I chose steel roofing was the ability to mount rigid panels directly to the seams of the panels. Sticking roll out solar arrays to the panels seems like a cheap and temporary condition.

Are there storage batteries available which could take and hold a charge? Would I be selling power to the electric company during the day and buying power in the evening? I'm not home during the day and my power consumption is minimal.

 

[uscitizen]

How many watts worth of solar panels are you installing? Also I would have then installed on brackets installed in the standing seams when the roof is installed.

Glueing them to the roof sounds a bit fly by night to me.

 

[Nosmo King]

How many watts worth of solar panels are you installing? Also I would have then installed on brackets installed in the standing seams when the roof is installed.

Glueing them to the roof sounds a bit fly by night to me.

I was hoping to get between 2 and 4 kw. It depends on the roof area and the budget. Rigid panels would be installed at the time of the roof installation. The steel panels are to be attached via a batten system of 2"x2" battens installed parallel to one another. The steel panels are 24 gauge steel and walking around on them as they are proud of the existing roof is not recommended.

 

[slackjawed]

I am going to use the PV panels as supplemental power. I could never generate enough solar power living here in the Pittsburgh area.
You are right, it does have to do with the location, ie; cloud cover most days. It also has to do with both the technology shortfalls and the transmission loss from the panels to whatever user interface you have. Even using 6ga copper wire, my loss was about 40% from the panels to my charge controller which was a distance of 16 feet.

My roofer suggested using solar panels which adhere directly to the steel roof panels. The southern exposure of the roof faces my neighbor in the back, the main entrance to the house is on the north side. Solar panels would be invisible from the street.
I suppose invisibility from the street is an issue in the city, I never had to worry about that problem. It is important to have a southern exposure.
I'm skeptical about this system. One of the reasons, besides longevity, I chose steel roofing was the ability to mount rigid panels directly to the seams of the panels. Sticking roll out solar arrays to the panels seems like a cheap and temporary condition.
I would advise isolating the solar panels from the roof panels. This can be simple or difficult. A simple way to do it to fasten an inert non-conducting material to the roof, then fasten the panels to that. (One could use 6" square 1/2" thick plexiglass glued to the roof (to maintain the warranty on the roof panels) then screw the panels to the plexi-glass squares. Any non-conductive material will work, but synthetics last longer than wood. a pair of 'squares on each end of the array, and a pair between each panel in the array would allow fastening the corners of the solar panels to the 'squares'. The reason I recommend isolating the solar panels from the roof panels is because of something called "galvanic corrosion" that happens when two dissimilar metals are in contact with each other and a catalyst (such as water) is present. Not only will the roof panels and the frames of the solar panels eventually corrode. A current will be created that will interfere with the transmission of the power from the panels to your interface, causing a little more loss. In addition, this type of corrosion takes place inside the panel itself. The panel generates power by using dissimilar materials, which can be affected by the magnetic field set up from galvanic current. Transmission loss is like money, take care of the pennies and the dollars will take care of themselves.(
Are there storage batteries available which could take and hold a charge? Would I be selling power to the electric company during the day and buying power in the evening? I'm not home during the day and my power consumption is minimal.

There are storage batteries available. If you are planning on selling power back to the power company, you still need a small bank of batteries. I should also tell you that in order to meet the building code, if your house is wired to the grid (and it is if you have power now) the installation has to be approved and inspected by your local power company. Most power companies have an interface that they require that you use. Most power companies also have a requirement for who installs the interface. The interface usually consists of a small battery bank and an inverter. The inverter transforms the power from the output voltage of the panels to a 110v circuit. The battery bank allows the current to the inverter to remain constant, something the current from the panels themselves is not.
Have you done the cost analysis yet? Most installations plan to recoup the cost of the system over ten years.
There are few things to consider that you will not find from the manufacturer. The first thing you will learn is that a 100 watt panel does not put out a full 100 watts for very long. Solar panels have a thermocouple built into them to prevent them from burning themselves up. Here in AZ, that meant that I only got power for 2 to 4 hours a day. It gets hot here. I get more power on cloudy days here because of that. I get a smaller output, but over a longer period of time. In theory the thermocouple will shut down the generating panel and it cools off. But when you put a dark colored object in full sunlight, it does tend to stay hot for a long time. That's right, solar panels are designed to be placed in the sun, but when they get hot they shut down. Baffles the mind, but don't worry the technology is getting better and will continue to do so. Anyway, Plan on getting about 60watts output from a 100watt panel in full sunshine. Maybe as little as 10watts on a cloudy day. As you can see the generating power itself not constant. That is why you need a battery bank to supply a fairly constant current to the inverter. Most solar panels generate 12v DC power on their own. They can be wired in a series and charge a 12v battery bank, or parallel wired to voltages up to 48volts. The higher voltages lose less in the transmission lines, allowing for longer distances between the panels and the interface and smaller wire sizes to do it with.
I would advise you to have a serious conversation with your power company's engineer, he can give you the best information for your area.
Good luck!

 

[slackjawed]

I'm sorry Nosmo, I mixed what i wrote into the quote from you, thinking that would make it less confusing, however upon seeing it I see it is hard to tell what you wrote as opposed to what I answered with.

 

[manu1959]

This spring, two big projects here at my home, the Pimplebutt Estate, will be replacing the existing (and failing) asphalt shingle roof with a standing seam steel roof (rare in these parts), and installing photovoltaic solar panels.

Anyone here have any experience with projects like these? Any tips?

I'd really appreciate your input.

yes.....good for you getting off the grid....stsanding seam roofs are bullet proof but if it rains our hails where you are the sound of the roof will be much louder when it hits it....

 

[Nosmo King]

I'm sorry Nosmo, I mixed what i wrote into the quote from you, thinking that would make it less confusing, however upon seeing it I see it is hard to tell what you wrote as opposed to what I answered with.

That's okay, I read between the lines, so to speak! I had no idea the loss was so great! And 6ga copper?!? I like the idea of isolating the panels to prevent galvanic corrosion. BTW, before i took my current position as Housing Codes Inspector for my county, I was an Environmental Engineer and I conducted oversight on UST (underground storage tank) installation. There, we usually installed a sacrificial anode on steel tanks.

Thanks a lot for your input. As the project progresses, the first step is getting the numbers, then getting the loan, I'll fill you in!

 

[Nosmo King]

This spring, two big projects here at my home, the Pimplebutt Estate, will be replacing the existing (and failing) asphalt shingle roof with a standing seam steel roof (rare in these parts), and installing photovoltaic solar panels.

Anyone here have any experience with projects like these? Any tips?

I'd really appreciate your input.

yes.....good for you getting off the grid....stsanding seam roofs are bullet proof but if it rains our hails where you are the sound of the roof will be much louder when it hits it....

I'm in Pittsburgh and it rains here more than Seattle! I have aluminum siding (it was existing on the house when I bought it in 1990) so noise from precipitation is not a real concern.

 

[LOki]

This spring, two big projects here at my home, the Pimplebutt Estate, will be replacing the existing (and failing) asphalt shingle roof with a standing seam steel roof (rare in these parts), and installing photovoltaic solar panels.

Anyone here have any experience with projects like these? Any tips?

I'd really appreciate your input.

Find someone with a solar pathfinder or similar instrument to assess the shading over your proposed installation.

Solar panels/arrays are connected in both series and parallel to meet your design requirements. As such, something like the shadow from a plumbing vent pipe could possibly shut your solar electric harvest right off.

That would be a sucky thing to discover after the fact.

Also, if you're not interested in any grid autonomy, don't bother with a battery bank and save $$$--use the grid as your storage.