Solar panel angles.

[gtojohn]

All electric home, if you don't already have a heat pump I'd compare your cost of replacing your outdoor unit with a heatpump vs the extra solar string. The average minimal heat pump uses about 1/3 the power of electric strip heat. That could be considerable since most strips are 10-15kw and bigger systems have mulitple strips. Its usually cheaper to make things more efficient than to add panels to generate more power. Remember the utility company buy back of solar isn't much. Because the usual utility rate structure is tiered, the first 500kw or so of usage is often very cheap, much cheaper than over building your solar. Our kw rate doubles after the 500kw. From a cost payback standpoint I recommend just enough to keep your average low bill inside the cheap energy tier.

[gasstingy]

Originally Posted by JRMichler

And up north where I live, I would seriously consider installing solar PV panels vertical: Summer power generation will still be greater than winter.

I want to address this thought only, as I don't know all of the ins and outs at different latitudes nor do I know your seasonal weather patterns.

However, I do know that in Arab, AL my 2 solar arrays present their best daily numbers in the winter despite the days being much shorter. My very best summer day stands at 42 kWh and my best winter day stands at 49 kWh. It has been my experience that solar panels really like clear and cold weather. BTW, my little array uses micro inverters and the big one uses a Sunny Boy 5000. Both perform enough better in the cold to beat any summer day. We just happen to have longer periods of dreary weather in the winter sucking the life out of our production when compared month to month.

So, I'd say, that if your weather is mostly dreary in the winter and you really don't want to bother with seasonally adjusting your solar panels, go with the season that has the most overall sunshiny days. [My default assumption is that everyone is grid tied until mentioned otherwise.]

[creeky]

I would put the panels at latitude if I was going fixed and I didn't have to worry about snow. That's a nice even draw between summer and winter and you get spring/fall as bang on.

But I would also consider putting my panels on an adjustable rack. A seasonal manual adjustment pays off big. And the racks are relatively cheap. Most "pro" electrical stores sell them now. 5 years ago I made mine (1kw array) out a few pieces of pressure treated lumber and dock hinges. You know for a 100 bucks.

While I'm at 45 lat. I do see 30% greater summer time efficiency in my adjustable panel set compared to the one I have fixed for winter. Now the adjustable panel set is also higher in the air. So it gets a bit less tree shade. I also doubt you'd see the same magnitude of addition, but it does make a difference. I suspect it would easily cover your dad's a/c use and then some.

I am in the process of putting my fixed array on my new tractor barn. That will raise it up, subtracting about an hour of tree shade. The aforementioned dock hinged adjustable rack will help with extra power. Even with the long days of summer, there's always something you can run to use more power.

I'm off grid. Running an a/c unit in my studio for free. Or on a sunny day running the dishwasher while seeing the batteries in "equalize" and knowing all the electrons scrubbing your dishes are coming directly from the sun. Pretty good feeling.

[WisJim]

In the 34+ years that my oldest PV panels have been in use, they have been through many hail storms, including one that punched holes in a shed roof, dented vehicles, etc., and another that severely dented vehicles and broke windows. The panels have had any damage from hail or anything else. The panels that I have seen that have been damaged (not my panels) had the glass break due to twisting or bumping the corners of the panels during handling or installation. I don't think hail is worth worrying about.

As far as angle, all of my PVs are on adjustable racks, but if they had to be fixed I would make them a bit more vertical than latitude to better shed snow in the winter.

[netzero]

Thanks for your post and for your question: lots of good info in all of them to consider. I think I got them all and did not see any reference to the panel type affecting production. We live near Philadelphia and have installed more than a dozen systems for clients both with string inverters and a few with the enphase product which we find fails at a 10% rate after 3 years.

Philly is surprisingly cloudy: almost smack in the middle between Tucson and Seattle in the numbers. Because of their hybrid Mono/poly cell technology, Sanyo was yelling pretty good in 2011 and 2012 that they could out produce other panels in our climate and so we took them up on a system for ourselves. because of multiple roof angles and use of enphase we were able to do a study and by panel and by panel type and location and could answer some questions for ourselves. As a rule we found that with enphase ,Sanyo panels outperformed Solar worlds in similarly angled strings by a factor of 12% with shading being equal. We also installed solar on an awning over a solar south facing windows and found these panels outperformed all others with a white roof under them; even when angled at latitude. Interestingly, the 12% (almost exactly) held true in this position as well. We theorize the awning panels ran cooler minus the roof and with the cooling column of air rising up the face of the building. We cautiously conclude that the Sanyo (now labeled Panasonic) in our climate will outperform a solar World that does not enjoy the Hybrid HIT technology. Since we first installed them in 2010, we have never had a failure from Sanyo and Decay at 4 years runs about 1.75%.

[philb]

Good info netzero.