Panel tilt

mactech

Solar Enthusiast
Joined
Sep 15, 2021
Messages
33
For that, multiple orientations.

A single orientation will have a curve of production that falls off when sun is at an angle.
Two PV arrays oriented at 10:00 AM and 4:00 PM will present 0.7x as much area toward the sun but have a more broad curve, flatter on top. It can deliver 1.4x as many kWh/day for a given peak power. These arrays could have separate SCC (or MPPT input), but can be paralleled into a single one for better utilization of the electronics.

Delivering more power early and late in the day means battery kept fully charged longer, starts recharging sooner. Smaller battery is sufficient to get through the night.

PV panels are cheaper than batteries, so good to over-panel and buy less battery. But limit max charge current to what battery can handle.

This was my goal to use 4 panels, 2s2p with each group pointed ~ 35 degrees from noon winter sun angle. I will have just one MPPT charge controller @145Vmax using the LV2424 MSD 2.4KW . Planning to use Talesun 330w panels with 40VOC max which I am ready to click the buy now button on. Starting with 24v @ 100AH LiPo ( 2x12) and hope to add another in parallel soon.

The panels will be about 25 feet away from the batteries in a heated box. What guage wire would you recommend for two panels at 80VOC for that distance?

Do I need a combiner for the two groups of panels or is the one not affected by the other when not getting sun?
 

JRUD

New Member
Joined
May 21, 2021
Messages
13
To summarize:
-Depends on what you are going to need power for. (winter vs. summer things). Optimize for that season.

I use the NREL PV watts calculator. SImple, flexible and NOBODY WILL CALL TO SELL YOU STUFF. My latitude is 40 (Philly).Rule of Thumb would dictate a 40 degree angle year round but 25 was most pracitcal for me. Interesting that Zero and 25 degrees gives me about the same kwatt-hrs in the summer time. From the attached comparisons it does not appear to make much sense for me to bother with tilt ups during the summer.
 

Attachments

  • PVWatts Calculator-0 degrees.pdf
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  • PVWatts Calculator-25 degrees.pdf
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DaGoose13

Solar Enthusiast
Joined
Jul 28, 2021
Messages
102
To summarize:
-Depends on what you are going to need power for. (winter vs. summer things). Optimize for that season.

I use the NREL PV watts calculator. SImple, flexible and NOBODY WILL CALL TO SELL YOU STUFF. My latitude is 40 (Philly).Rule of Thumb would dictate a 40 degree angle year round but 25 was most pracitcal for me. Interesting that Zero and 25 degrees gives me about the same kwatt-hrs in the summer time. From the attached comparisons it does not appear to make much sense for me to bother with tilt ups during the summer.
Looks like your system losses are different between the two reports.
 

Richard Lee

New Member
Joined
Mar 18, 2021
Messages
9
Location
Woburn, MA
Solar Radiation Monitoring Laboratory Department of Physics
http://solardat.uoregon.edu/SunChartProgram.html this will help you calculate what you need.
I used before I built the adjustable tilt into my semi-fixed array rack.
If you do want to make it adjustable, you might want to add a one foot shadow-stick.
Install the stick in the center of a white 3 or 4 inch disk. You can check it around noon,
and tweak you angle adjuster for max power. From the pdf chart, I found that mid winter
sun is very low, north of Boston. So the angle is steep. But that allows the snow to slide off.
The plot attached is the data for my area. Study it and you'll find a ton of info.
 

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  • plot.png
    plot.png
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wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
874
Solar Radiation Monitoring Laboratory Department of Physics
http://solardat.uoregon.edu/SunChartProgram.html this will help you calculate what you need.
I used before I built the adjustable tilt into my semi-fixed array rack.
One of the advantages of using the NREL PVwatts estimation tool is that the simulated hourly production data accounts not only for your latitude and longitude, array orientations and tile, PV array and inverter characteristics but importantly it also accounts for the weather patterns typical for that location. e.g. seasons where morning fog or afternoon storms might be in play and not accounted for by sun charts.
 

Richard Lee

New Member
Joined
Mar 18, 2021
Messages
9
Location
Woburn, MA
That extra info might be real good for calculating your KWH based on typical weather. A person might actually learn they're going to need twice the PV they were planning to buy. Had I known how little power I was going to get from my Panels, I probably would have waited a few years.
 
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