Camp Solar Setup (1 Viewer)

[PabloVTA]

"our" baja trip?
what am I cooking? and when?

 

[e9999]

guys... that latitude tilt recommendation is based on an AVERAGE for the YEAR for a FIXED panel! Unless you are going to spend the whole year in Baja and will not move the panel at all, a fixed latitude tilt is NOT the best way to go. In the summer you are much better off with a horizontal panel and in the winter much better off with a tilt bigger than the latitude angle. That is if you are going to leave the panel fixed the whole day which is not the best way to go anyway. If you want close to max power just point the panel at a point a bit ahead of the sun a couple of times during the day, and you'll come out way ahead.


added: if you want some numbers for context here you go:

take a 1 sq ft piece of paper, hold it at arms length in a vertical plane. It looks like 1 sqft when you look horizontally at it.
Now tilt it at 30degrees from the vertical. Now it looks like 0.87sqft.
Tilt it at 45deg it looks like 0.71sqft.
Tilt it at 60deg now it looks like 0.5 sqft.
So if your panel is off from the direction of the sun by 45deg you are losing 29% -about a third- of the max power you could get at that instant. Needless to say, the sun moves (apparently) a lot, by about 180deg in the summer, so want to bet you're off by more than 45deg more than just a little bit during the day if you are in a fixed position?

 

[TrickyT]

The efficiency improvement of sun tracking is going to be related to location and time of year, and someone must have an app for a smart phone that would tell you what the available solar flux is for any given latitude and date. Anyone know of one?

Here's a $2 iPhone app that has options specifically for portable panel users, including tilt and rotation angles for receiving the optimum solar flux from the current time through sunset: Solar Tracker on the App Store. There are also plenty of free apps, but most are for determining best position for stationary panels.

 

[Hedgepig]

Can I remind everyone that the planet axis is tilted - our measurement of latitude = zero does NOT equal straight on to the sun. This will affect higher and lower latitudes more than those near the equator but the effect is evident at all latitudes and the effective angle to the sun changes with the seasons (hence solstice, equinox). Its current value is 23.4 degrees. A fixed angle of solar panel as suggested above would at least allow panels to point more directly at the sun at midday....but to get the most out (if you can be bothered) of the sun there is no fixed value.....either manual or automated turning is the way to max out.

I use Sun Surveyor Lite app to predict where the sun will rise in the morning....as a photographer it is useful to predict where I'm going to get the best light in the mornings for my photos too. I point my panels that way (and at the right angle) before I go to sleep

 

[JCruse]

guys... that latitude tilt recommendation is based on an AVERAGE for the YEAR for a FIXED panel! Unless you are going to spend the whole year in Baja and will not move the panel at all, a fixed latitude tilt is NOT the best way to go. In the summer you are much better off with a horizontal panel and in the winter much better off with a tilt bigger than the latitude angle. That is if you are going to leave the panel fixed the whole day which is not the best way to go anyway. If you want close to max power just point the panel at a point a bit ahead of the sun a couple of times during the day, and you'll come out way ahead.


added: if you want some numbers for context here you go:

take a 1 sq ft piece of paper, hold it at arms length in a vertical plane. It looks like 1 sqft when you look horizontally at it.
Now tilt it at 30degrees from the vertical. Now it looks like 0.87sqft.
Tilt it at 45deg it looks like 0.71sqft.
Tilt it at 60deg now it looks like 0.5 sqft.
So if your panel is off from the direction of the sun by 45deg you are losing 29% -about a third- of the max power you could get at that instant. Needless to say, the sun moves (apparently) a lot, by about 180deg in the summer, so want to bet you're off by more than 45deg more than just a little bit during the day if you are in a fixed position?

You're right about the tilt of course (awesome formula!) but where I am the sun is so low that the trees block the sun all day, until perhaps April, at least.
Just wanted to throw that variable into the mix as there are a minority on here in the same dim and dark boat as me.

Plus as I said earlier, my panel was making 20V the other day just from pointing straight up at a cloudy winter sky. That's a good 90% of full summer voltage.

I'm surprised that panels are that different. That some need to be aimed and others don't.

 

[Cruiserdrew]

Plus as I said earlier, my panel was making 20V the other day just from pointing straight up at a cloudy winter sky. That's a good 90% of full summer voltage.

I'm surprised that panels are that different. That some need to be aimed and others don't.

You realize the no load volts has NOTHING to do with the power available from the panel? It's only based on the number of cells. You could light it with a candle and get the same open circuit voltage.

Aiming the panels increases the available power in ALL panels. It's an energy density thing dictated by the geometry of where the sun sits on the horizon and the angle of the panel.

 

[JCruse]

Everyone is talking about what what they've observed about solar panels based on their own, but no one is saying what kind of panel they have! Monocrystalline, Polycrystalline, Amorphous, etc, which all have differing characteristics.

 

[abuck99]

SunPower is a US manufacturer that produces some very efficient cells for panels (highly rated proprietary technology) efficiencies typically upwards of 22% (in monocrystalline). These aren't the cheapest though. You might find some good ideas for portable options here including brands using SunPower cells: Portable Solar Panels