Here is (another!) really common question that I get:
“I’ve got 3 quotes for solar: The first company says my roof is at the wrong pitch and wants to charge me hundreds of dollars extra to put my solar panels on tilt frames to optimize the amount of electricity I get. The second mob say it is fine to just put the panels flush on my roof and the third guy says that, yes my roof isn’t at the perfect pitch, but the best solution is to mount them flush to the roof and simply add an extra solar panel to make up for any reduced power output.
Now I’m really confused! Help!”
The problem here is that there are 2 extremes of solar installer in my experience:
At one end of the spectrum you have The Solar Purist. He is only happy if the solar panel is positioned for the absolute optimum power output – he is a perfectionist, highly technical, and has been in the industry since the dawn of solar, when solar panels cost 10 times what they do today. He thinks a few hundred dollars is a small price to pay to squeeze a bit more power out of those precious solar panels. And please, never, ever suggest to him that he uses a non-German inverter. Or feed him after midnight.
Then at the other end of the scale – you’ve got the “She’ll Be Right” Solar Installer. He just wants to get the install done. If you’ve got a roof, and it doesn’t face south and it’s not completely shaded he’ll bang the panels on, and move on to the next job.
I would argue that the best installers for your home are somewhere in the middle. i.e. ones that will give you a safe install that is not “Gold Plated” but will still maximize your return on investment.
In terms of whether to install tilt frames or not – this means that a good solar installer should show the financial consequences for each option and let you decide whether tilt frames are a good investment or not.
So let’s look at a typical scenario where tilt frames would be an option and see which of our 3 original options makes the most sense from an economic perspective:
To Tilt Or Not To Tilt
That is the question. Whether ‘tis nobler to suffer the slings and arrows of the solar purists, or just get the best ROI…
How to work out if tilt frames make sense or not:
Imagine you have a house in Adelaide (lucky you!) with a North facing roof that has a very shallow slope of 10° and you want to install a 3kW system.
The perfect tilt angle for solar panels is the same as the latitude of the install location. Adelaide has a latitude of 34°.
The Clean Energy Council installation guidelines say that the tilt-angle of the solar panels must within 10° of the Latitude. So if we follow those guidelines, we’d have to use tilt frames for our solar panels right?
Panels at the perfect Angle:
If we crunch the numbers with my favorite free, online solar power analysis tool, PV Watts, then we can quickly work out that 3kW of north facing solar panels at the perfect angle of 34° will produce 11.9kWh per day averaged over 1 year. If we value our electricity at 25c per kWh, then that earns us $1088 per year.
Panels at 10°
If we crunch the numbers for 3kW of North facing solar panels at only 10° then we discover that we get 11.4kWh per day which makes us $1041.
How much do tilt frames cost?
Assuming our 3kW system uses 250W panels, the extra cost of tilting 12x250W panels should be around $300.
So to make an extra $47 per year, we are going to be spending $300. About a 6 year payback. Whether you think this is a good investment is completely up to you. But your solar installer should give you the numbers so you can make an informed decision!
I personally wouldn’t bother, mainly because, if you use tilt frames on your roof, you can fit fewer panels on that valuable roof space. Why? Because you need to leave extra space between the panels so that one row of panels doesn’t cast a shadow on the row behind it. I also think that tilt frames are butt-ugly. But perhaps that is just me.
What about adding an extra panel?
The third option you have – is to make up for any lost power by simply adding an extra solar panel. A few years ago, when panels were 5x the price, this would have been an insane suggestion (and some old school solar installers still think it is a terrible waste!). But in 2012 it can make a lot of sense.
The cost of one extra 250W panel will be about $400. Installed flush to our roof, this 13 panel system will generate 12.36kWh per day and make us $1128 per year. So your extra $400 investment is returning you an extra $169 per year compared to the 12 panel system at 10°. And an extra $128 compared to the 12 panel system mounted on tilt-frames at 34°.
I’d say that the extra panel is a much better investment that the racking. The third installer was right!
Note: One thing that you don’t want is completely flat panels (angle = 0°). You want them to slope at least 10° so that the rain flows down the slope and helps the panels self clean.
Are you a fan of tilt frames for solar panels? Then let rip in the comments below!