solar panel angle

bmet

After upgrading to a larger solar panel, I used the position of the first as a starting place. The larger panel is mounted above a doorway to a remote shed, and I need to adjust it.
It is currently facing due South, dipping 20 degrees below local horizontal.

In checking with various web sites, hardly any of them agree on the angle calculation. Some advise to use just the Latitude. Others get more specific, Latitude +15 or -15. Other get more specific still, Latitude x 0.92 - 3.1 And so on, and so on.

This is going to be a fixed install, and one site gave recommendation of the best 'year round' angle as 25 degrees, for the shed's zip code of 78861. Is this close?

Thank You.

niel

Re: solar panel angle

it may depend on the application. for instance, if used primarily for a cabin in the summer then the angle could be less than or equal to your latitude. also, the weather can play a part as if snow is present during the winter then go with greater than or equal to the latitude for a shaded panel does not like to produce good usable power.

now you state it is adjustable so maybe you can adjust it several times a year for better collection. i suppose you guessed it that there isn't a definitive answer as there are variables involved. one does start with the latitude as default and you may go from there for whatever reasons.

bmet

Re: solar panel angle

It is a remote shed, used a couple of times a month. It doesn't snow there, or rain much, so sunshine is usually in abundance year round. The mounts are not readily adjustable, this is why I'd like to make it count. The first panel I set was by a T-square, at mid-day, ensuring there was no shadow. At the time, that angle was at about 21.5 degrees below local horizontal, but I don't remember what time of year.

Cariboocoot

Re: solar panel angle

Mac's Lab has a good explanation of panel angles and the effect on production: http://www.macslab.com/optsolar.html

There is even mention of factoring in what time of year you need the most power.

BB.

Re: solar panel angle

Many times, people use more lighting in a shed during the winter (less daylight) and have way more power than they need in the summer--So optimizing for winter is not always a bad thing.

-Bill

bmet

Re: solar panel angle

Thank you B.B., Niel and Cariboocoot. That link you referred is where I got the 25 degrees, for the year round fixed angle.

Summers are hot & humid there, so my goal is to harvest enough for my power pack to run a big fan in the shed when I seek refuge from heatstroke 8) Two visits a month, I should always have a ready supply.

icarus

Re: solar panel angle

IN the real world, a few degrees off angle is not going to effect things too much. Orienting for the longest amount of sun, keeping shading issues to a minimum etc are probably more critical. My vertical wall mount panels only put out a few more watts when tilted to optimal angle. A big deal with a big array, not so much with a single panel.

Tony

mike95490

Re: solar panel angle

1) be sure you aren't draining your battery bank over 1 or 2 days, and thinking that the PV will recharge it in a week while you are absent. After day 2, while the battery is still low, sulfation will begin in your batteries.

2) I optimized my array tilt for winter production, since that's when I have the least hours of sun, and will be using more indoor stuff. Summer, I'm fine.

bmet

Re: solar panel angle

I don't leave electronics running unattended. My parents taught me that.

mike90045 wrote: »

1) be sure you aren't draining your battery bank over 1 or 2 days, and thinking that the PV will recharge it in a week while you are absent. After day 2, while the battery is still low, sulfation will begin in your batteries.

2) I optimized my array tilt for winter production, since that's when I have the least hours of sun, and will be using more indoor stuff. Summer, I'm fine.