Is your Solar panels in the mist productive direction? DR ENERGY SAVINGS?

arrugala

Bronze
Nov 7, 2010
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You?d think it would be easy: the sun is ?up,? and, like leaves and basking reptiles, solar panels should face in that general direction. But most installers of solar panels, especially the ones for homes, follow conventional wisdom handed down from architects, which holds that in the northern hemisphere, windows and solar panels should face south.
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This makes intuitive sense since it would seem to maximize the amount of sunlight a panel will get as the sun tracks from one horizon to the other. But it isn?t true, at least according to a single study of homes in Austin, Texas. The Pecan Street Research Institute found that homeowners who aimed their panels toward the west, instead of the south, generated 2% more electricity over the course of a day.
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More importantly, those west-facing panels reduced household electricity usage during the times when electricity is most expensive?and power grids are most likely to become overloaded?by 65%, while south-facing panels only reduced usage during those times by 54%. In Texas, as in most places, those ?peak times? are from 3pm to 7pm, and correspond with the heat of the day.
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It?s obvious that west-facing solar panels produce more electricity later in the day, when the sun is setting in the west, but quantifying the way that favoring late-day sunlight helps homeowners save money and utilities flatten out demand could lead to a simple but effective hack for the world?s solar installers: Simply re-orienting solar panels could shorten the amount of time it takes for them to pay for themselves.
 
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grsher

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Jan 16, 2008
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They already have that figured out. By facing the panels due south with the proper tilt the most kilowatt hours will be received. If they have a roof top mount then the main determining factor will be the orientation of the house if it has a sloped roof.
You are also correct that if a time of day usage is used to calculate rates you may save more on your electrical bill by having them face in a westerly direction.
 

drSix

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Oct 13, 2013
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So, would it be safe to say that pointing your panels southwest would be a good idea. Is there an angle that is better than others. I am going to try and build a couple next month.
 

grsher

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Jan 16, 2008
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Only if you were getting paid more per kilowatt hour in the afternoon would it make sense to point them SW. Otherwise due
south at the correct tilt, which is determined by your latitude, would generate the most KW hours per day. As that study states
it was a small sampling of homes so not necessarily accurate.
In the DR net metering is used to help save on electricity consumption so the time of day usage wouldn't factor in.
 

drSix

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Oct 13, 2013
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I am building panels for my pool, it will not be grid tied. I need adequate power for as long as I can get it.
 

Lothario666

Bronze
Oct 16, 2012
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If your panels are going to be ground or pole mounted face them due south. Here is a link that will give you information about tilt and direction of your panels. Someone else posted it in this forum before but here it is again.
Solar Irradiance - calculate the solar energy available on your site
Perhaps it's just me but that calculator seems to have a problem, once you choose a city and direction, the numbers do not change when you then change the direction of the panels. I tried "Facing East" and then changed to "Facing West" and no change in numbers. Had to change which city, then come back to the city I wanted and re-choose a direction of the panel for numbers to change. It's flaky about changing the panel direction.
 
May 29, 2006
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No need to overthink the problem.

The DR is in the tropics. There are times of the year when the sun is north of the island. You can find DIY videos on YouTube on how to make tracking devices. In the DR, you really only have to worry about east to west. If calibrate on the Equinox, the most the panel will be off north to south is 23?, which isn't worth bothering about.

A friend of mine once asked me how to calibrate his system. I told him to put something on the panel until and adjust it until there was no more shadow. No shadow means it's pointing at the sun...
 

grsher

Member
Jan 16, 2008
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Perhaps it's just me but that calculator seems to have a problem, once you choose a city and direction, the numbers do not change when you then change the direction of the panels. I tried "Facing East" and then changed to "Facing West" and no change in numbers. Had to change which city, then come back to the city I wanted and re-choose a direction of the panel for numbers to change. It's flaky about changing the panel direction.

Every time that you change the direction you have to change the tilt also unless you want the panels to be mounted flat in which case the readings would always be the same no matter the direction.
 
May 29, 2006
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The panels can only produce so many watts, and after a certain point of sunlight, you don't get any more power out of them. Otherwise, it would be much cheaper to simply point mirrors at a panel to get more power out of it.

The north south adjustment never changes by more than a fraction of a degree each day.

You can make a simple tracking device using a couple photoresistors and some small motors or a smaller panel to drive the motor when the sun hits it. Even in the DR, you should be able to get the components..
 

grsher

Member
Jan 16, 2008
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The panels can only produce so many watts, and after a certain point of sunlight, you don't get any more power out of them. Otherwise, it would be much cheaper to simply point mirrors at a panel to get more power out of it.

The north south adjustment never changes by more than a fraction of a degree each day.

You can make a simple tracking device using a couple photoresistors and some small motors or a smaller panel to drive the motor when the sun hits it. Even in the DR, you should be able to get the components..

Solar panels can produce more than their rated power. This is why when you are sizing the wire you have to allow for 25% more power from the modules(panels). This is because close by reflective surfaces such as water, snow and colder temperatures up north, and even clouds can reflect more than the STC (Standard Test Conditions) rated value of 1000 watts/sq. meter.
You may be able to make a simple tracking device cheaply but how long is it going to last? The modules will last 25 to 30 years. With the lower cost of modules these days it is generally thought that the cost of buying and installing a tracker is not worth the extra money. Simply, if you have the space, add a few more modules. If you don't have the space then a tracker makes sense.
 
May 29, 2006
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Great to see they are becoming cost effective. I was in the DR in 1993 on a trip with my dad for Peace Corps and we were looking at the potential for panels in rural villages off the grid. The best use then was for colmados so they could stay open later and have a radio and also for kids so they could use ONE compact fluorescent to study with.

Now with LEDs and other tech, it's not so unreasonable to live off the grid. It's when you get to using AC and pumps that solar has a hard time for start-up costs and pay back times. Refrigeration/AC has got some new tech coming out that could change things too including a solar powered heat pump.

As for tracking, I agree it may not be worth it in the tropics..
 

Smart

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Jun 16, 2012
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I hAve a solar panel on my backpack that keep the refrigerito in the roo sac cold as long as I have sun! and my Walkman powered up all day.
The name is Millet France. Yes it cost $700 but is a nice pack when I go AWAL.
 

dv8

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Sep 27, 2006
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our neighbour have few sets of solar panels and all i know is that they point away from the golf course right outside the wall. protected by the netting too. we get them balls in the garden and sometimes even inside the house. so maybe it's not where the technology tells you but where common sense suggests?