# Solor roof



## SPS-1 (Oct 21, 2008)

You normally want the solar panels angles up somewhat. The further south you are, the less angle. Putting them parallel to the ground is not the end of the world unless maybe you are up north. You can buy/build racking to hold the panels at an angle but that adds to the costs.

I am no expert on flat roofs, but probably the biggest hurdle is that you really don't want to be putting screws through your flat roof. Is there other structure that the aluminum racking can be mounted to without going through roof membrane?


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## Deja-vue (Mar 24, 2013)

That is BS, just take a look at these:

https://www.solarelectricsupply.com/residential-solar-systems/flat-roof-mounted

Try to make them facing south and you are golden.


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## Mystriss (Dec 26, 2018)

Up north in Alaska we have to put them on a pretty good angle or they're useless because of the angle of the sun.

That said, I'm gonna agree with Deja-vue on the BS call... They can put a roof mount on that'll let you angle the panel any way you want, we actually specifically talked about it because the summer angle is different than the winter angle up here. (One of the reasons we decided not to bother was the maintenance, we'd have to keep them clear of snow and change the angle at least twice a year. My husband doesn't wanna go on the roof at all, much less two - ten times a year, mostly in the winter.) They said for the money we could get a mount system that changes the panels angle on the fly to match the path of the sun.


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## Calson (Jan 23, 2019)

There is the mistaken assumption that sunlight has to hit a panel's cells at a 90 degree angle to provide good output. Panels are designed to produce electricity at much less angles and are effective on RV roofs where they lying flat. 

Ideally angle is roughly that of the latitude of the location so at the equator no tilt is needed and in Maine the tilt should be 45 degrees. But the tilt for best year round output is different than the angle that provides the least loss in the winter or the most output in the summer, depending on your needs. 

This website is very useful in calulating monthly output for a given location and system depending on the amount of tilt. I used it to run multiple tilt scenarios for my house as I have a section of flat roof and could use any tilt I wanted. 

http://csi-epbb.com/

At my location the optimum tilt for maximum yield over 12 months was 20 degrees but going to 10 degrees the reduction was from 5,007 annual KWh to 4,784 KWh, so not a big difference at 0.4 percent. This reflects how efficient today's panels are with low angles of sunlight hitting them. 

I wanted to fit two sections of panels to maximize the output and needed to avoid having the front section shading the section behind it and that altered my "perfect" angle as well. I actually had one array with the panels set with a horizontal or landscape orientation and the other array with them in a portrait orientation. I used an dual string inverter as the output was different from each array.

To us the adding of solar panels was a no-brainer decision. Houses with solar in California sell for $17,000 more than comparable houses without solar and they sell in half the time on the market. Out system cost us $17,000 out of pocket and we now pay the utilty company a $5 a month meter fee. We were paying over $0.34 per KWh to the local utility company and we knew that number was only going to increase in future years. 

Only caveat with adding solar is that it can cost up to $3,000 to have them removed and put back on the roof when reroofing a house. We elected to reroof our house where the panels were going to be installed and upgraded the roof insulation with solid foam panels at the same time.


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## BoBBuild (Aug 26, 2019)

Positioning of solar panels are usually angled up a bit, but I believe that flat position also works. If we talk particularly about solar roof project, I, indeed, believe it can be positioned flat. One of the benefits you might be missing out on is the effectiveness of angled solar panels - they produce 20% more energy on average.


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## Oso954 (Jun 23, 2012)

There are ballasted racking systems for flat roofs. The racks are weighted down, no roof penetrations. However, the ballasted system is not permitted in some areas. (High wind areas would be one reason for not permitting them)


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## josephung (Apr 16, 2021)

I'm thinking, is it possible to adapt a water heater to a solar power system?


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## SW Dweller (Jan 6, 2021)

josephung said:


> I'm thinking, is it possible to adapt a water heater to a solar power system?




Can a solar system produce enough power for a water heater,,, yes if it is big enough

can electric or gas water heater have solar added,,, yes solar hot water collectors are available

Now depending on the location is it worth the expense


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