4 Simple Ways to Find True Solar South for Aligning Solar Panel Correctly in Few Minutes (2019, Step by Step)

True Solar South vs. Magnetic South

Contractor is finding the True Solar South

It has been known that south-facing solar panel (In the Northern Hemisphere) can get the most out of sunshine.

And when it comes to orienting solar panels, most people will simply choose the south which the compass points to.

However,

this approach is absolutely wrong.

Because you will only be able to find out the magnetic south with it.

Actually,

In any PV system related project, we tend to set up solar panels to face the solar south rather than the magnetic south.

Although doing this only brings about a 3% improvement in energy collection, it will be a big deal if your solar array is huge or your extreme condition requires getting as much energy conversion as possible.

Now, the questions are:

  • How can we ascertain the true solar south?
  • What’s the difference between “True Solar South” and “Magnetic South”?

Well, today I am going to make it easy for you

Basic Knowledge: True Solar South vs. Magnetic South

Before we talk about the methods of finding true solar south, let’s go through the basic knowledge quickly

  • What is “True Solar South”?
  • What is Magnetic South?
  • Is there any difference between them?

This can be easily understood with the help of the following image (pic.1):

True Solar South vs. Magnetic South

pic.1 True Solar South vs. Magnetic South

In fact,

There is a giant magnet in the earth.

Its magnetic South Pole is around the Earth’s South Pole, while its magnetic North Pole is around the Earth’s North Pole (Refer to pic.2).

This big magnet rotates along with the Earth. However, its axis is not aligned with the Earth’s, although they are pretty close to each other. The declination is approx. 14 degree.

For better understanding:

When the compass needle points at the south, it is actually aligning with the Magnetic South Pole and not the true South Pole.

the earth poles vs magnetic poles

Pic. 2: the earth poles vs magnetic poles

We often refer to the direction of the Earth’s South Pole as the true south or the true solar south, while the direction of the magnetic south pole is referred to as the Magnetic South.

In the solar energy-related industry, accurately locating the true south means a lot to the solar PV system.

Lucky for you,

we have 4 proven practical methods you can use today to help you when adjusting your solar panel to ensure you find the right direction and improve the efficiency of your solar powered system.

Now, Let’s dive into the content step by step.

Method #1: The shortest shadow method

The shadow of an object will be shortest when the Sun is highest at noon, and at this moment, the direction of the shadow line is the true solar south.

This method involves simply finding out the shortest shadow at noon according to this theory,

Now, let’s dive into the steps

The shortest shadow method

Simple steps:

1. Set a straight stick on a flat ground in the morning, toward noon – it is important that the straight stick is set perpendicular to the horizontal, and the ground should be as flat as possible, because a tilt-mounted stick or uneven ground will produce a faulty result of the shortest shadow.

Tips: A plumb bob could efficiently help you put up the stick vertically on the ground.

2. Mark the shadow end on the ground every few minutes – as time passes by, the shadow cast by the stick will move. You need to leave a mark at the end of the shadow on the ground every 10 – 20 minutes, these marks will finally form a curve.

Tips: the interval is not necessarily the same, as long as we can get the moment when the shadow starts becoming longer, instead of shorter.

3. Find out the shortest shadow line – draw a line to connect those marks to the point where the stick touches the ground. By now, the shortest line is evident.

4. Reveal the true solar south – now that we have marked that special line we concluded in the third step, the direction of the Solar South has been revealed. You could then adjust your solar panels to align with this direction.

Method #2: Using a shadow at solar noon

This could be the simplest way – it takes far less time than Method #1

Let’s start with the question: what is solar noon?

Solar noon is the local time when the sun rises to its highest point at your location, and at this time, the sun is crossing your local meridian.

Instead of spending several hours standing outside and measuring the shortest shadow, in method #2, all you have to do is to find out your local solar noon, then go out at that time to check the direction of the shadow of an upright object on the ground.

Using a shadow at solar noon to find out true south

Here, you may still need to raise a straight stick vertically on the ground, but you can refer to Method #1 Step 1 for that.

We will introduce 2 feasible ways to calculate your local solar noon.

  1. A) http://www.spot-on-sundials.co.uk/calculator.html
  2. B) http://suncalc.net/

Now, let’s dive right in.

Online solar noon calculator A

Simple steps:

1. Visit the website http://www.spot-on-sundials.co.uk/calculator.html and input your location, longitude and time zone (I will use my location, Shenzhen, China as an example)

solar noon calculator

2. Get your longitude – open the Compass APP on your phone as below – you can see my location is Shenzhen and Longitude is 113° 56’ 27” E

Compass APP on your phone

3. Fill in the form with the required data and click on Display Calculator

solar noon calculator

4. You will be redirected to the page below. Click on “continue”

solar noon calculator

5. The solar noon calendar would be generated as below – this special calendar has listed all the solar noon for each day of the year. Assuming your team would go out to carry out this task on Nov 30th, 2018, the solar noon on that day is 12:14 pm

solar noon calculator

Online solar noon calculator B

Follow the simple steps below:

1. Visit the website http://suncalc.net/

solar noon calculator alternative

2. Drag the red mark to your address on the map. The solar noon will be displayed on the right side simultaneously.

solar noon calculator alternative

3. Select the date, for instance, Nov 30th, 2018

solar noon calculator alternative

4. You will get the same solar noon 12:14 as from calculator

solar noon calculator alternative

Since both calculators, A and B, show the same time 12:14, then your team can go outside at that time to mark the true solar south easily.

Try the steps above, and let me know if the two calculators also generate the same results in your city.

Method #3: The magnetic declination method

Seeking out truth south according to magnetic declination may be the most accurate method.

As we know, the magnetic south that a compass points to slightly deviates from the true south – the direction that is along a meridian towards the South Pole. The deviation angle between them is called magnetic declination.

The magnetic declination changes every year because magnetic poles are shifting each year. However, the Earth’s pole is not moving. Chances are we should go to authority online database to obtain up-to-date data of declination.

Let’s go through the simple steps:

1. Visit the authority site NOAA, and fill in the required data – taking my city Shenzhen as an example, my latitude and longitude are 22.40 N and 113.56 W respectively (refer to the images above). Select Nov 30, 2018, as the date, since my team plans to do this job on that day, and click on the calculate button.

magnetic declination calculator

2. Your magnetic declination would be displayed – from the results, you can see that my declination in Shenzhen China is 9.02 degree East.

magnetic declination calculator

3. Prepare the compass – we need a compass with degree scales. Place it on a horizontal surface, and adjust the needle to align with the south-north scale as below. Its black hand will point to the magnetic south

compass with scale

4. Rotate the compass horizontally according to the declination – my declination is 9.02° East, so we rotate 9.02 degree counterclockwise. Now, the ‘S’ on the scales will point to the true solar south. (Refer to picture below)

compass with scale

Tips: If your declination is 9.02 degree West, then rotate clockwise instead.

Method #4: the Polaris method

If you live in the northern hemisphere, you can also use the Polaris to locate the true north or south.

The Earth’s imaginary rotation axis always passes through the Polaris, so you may find she does not move in the sky, and the direction towards the Polaris is always the true north.

The Earth's imaginary rotation axis and the Polaris

With the basic knowledge above, let’s walk down the simple steps:

1. Identify the Polaris – Commonly, finding the Polaris requires the help of “Big Dipper” and “Little Dipper” in the northern sky. Below are 3 helpful clues

  • The Polaris belongs to “Little Dipper”, together with 6 other stars
  • The Polaris doesn’t move
  • The “Big Dipper” constellation revolve around the Polaris all year round.
“Big Dipper” and “Little Dipper” in the northern sky

“Big Dipper” and “Little Dipper” in the northern sky

 

Big Dipper and Polaris

Big Dipper and Polaris

2. Set up the solar panel – line up the seam between 2 solar panels with the Polaris as instructed in the following picture, and the solar panel will be facing the true south

the Polaris method

Some people like the Polaris method most, because it neither requires any calculation nor marking shadow for a few hours.

Which one do you think is the best method? And do you have any other more efficient method(s)?

We love to hear from you in the comments.

Polycrystalline vs Monocrystalline Solar Panel, Which one is better?

Polycrystalline vs Monocrystalline Solar PanelEvery day, a better and improved solar technology is being researched to effectively harness the sun’s energy.

The current solar technologies aren’t as efficient as we want, particularly as regards the solar panels used. Currently, there are just 2 popular types of solar panels, in spite of their inadequacies we need to know what each of them offer and how you can benefit from either one in your next solar purchase.

In this post, we covered extensively 2 types of solar panels. At the end you’d get to know their characteristics and compare both to help you in making the right decision.

Let’s get to it…

What are the Major PV Solar Panel Technologies?

There are different types of solar panel available today in the world and new ones are constantly being developed to ensure the inexhaustible energy of the sun does not go untapped.

The first of all solar cells ever created is the monocrystalline cell which was discovered in 1935 by Calvin Fuller and Gerald Pearson. This solar panel is by far the most developed of all solar panel technologies that could be employed.

Next is the arrival of the cost-effective polycrystalline cells which also has ever-since being improved.

There are other technologies such as the thin film solar panel which is suitable for regions with high temperature. In this article we shall stick with the most developed solar PV technologies. Which are the polycrystalline and the monocrystalline PV technologies.

What is a polycrystalline solar panel?

Polycrystalline materials are materials made out of several crystals (rocks) of silicon.

All crystalline PV panels are made of silicon. Scientists say it is the second most abundant element on the earth crust. Silicon is obtained from rocks and at all times it is found in its combined state as silicon dioxide.

How polycrystalline panels are made?

The process of making a polycrystalline PV panel can be quite tasking.

It starts by first extracting silicon from the rock by means of a very hot furnace of over 2,000oC. The furnace melts the rock into liquid, and this is then poured into a cooling machine. The result of this cooling is a pure silicon rock which is ready for processes to become a PV panel.

Silicon in its pure state is just a semiconductor which does not conduct easily because of its atomic structure. A material conducts when it has free electrons or free holes, but pure silicon does not have any. However, this can be improved by adding impurities to this silicon. The process whereby impurities are added to a pure element is called doping and the added elements are called dopants.

The dopant and the silicon rocks are mixed in a 3 ft x 3 ft square-shaped mold and the mold is inserted to a large furnace of temperature of about 2500oF. The mold stays in the furnace for about 20 hours for a proper melting process. It is removed after this period and allowed to cool for a day or two.

After the cooling a solid silicon block (ingot) is obtained. This ingot is sliced into a thin and fragile square shaped solid called wafer.

There are two stages when it comes to cutting an ingot; the first stage is where the entire solid is cut into a column of the required size but a very long width and the second stage is where the width is removed by cutting the column into the desired thin sheets -the wafer.

Though we’ve obtained the wafer the process is yet incomplete, unless the thin sheets are carefully collected and separated for the cleaning process.

Due to the fragility of these solids, hands are used to separate the solids individually and since hands are involved our material becomes more prone to contamination, because of this the wafers are washed properly after the collection.

Lastly is the addition of the last chemical unto the already washed wafers, this is then baked to obtain a fusion of the two materials.

Other finishing touches will be; addition of anti-reflective clothing on the panel, addition of chemicals to help the panel to better conduct electricity out of the panel, addition of aesthetic value to make it more visually appealing and addition of electrical contacts to help convey out the converted electricity.

What is a monocrystalline solar panel?

It is called monocrystalline because of how it is made or more appropriately, how what it is made from i.e. it is made out of a single crystal (of silicon).

How monocrystalline solar panels are made?

Unlike the polycrystalline panel which is gotten from many silicon crystals obtained melted and directly cooled, the production of a monocrystalline panel involves a more complex process ‘the Czochralski Growth’

After obtaining the silicon rocks from its parent rock, it is melted in something like an enclosed flask called the ‘Czochralski Growth Apparatus’. This flask has a heater in its innermost layer with a graphite bowl that contains the silicon rocks. The innermost layer is succeeded by another layer called the heat shield located in a space called the chamber.

Once the silicon is melted, a certain material called the ‘seed crystal’ is dipped into fluid and is pulled back up while rotating. The seed crystal continues to rotate as it moves up, while the graphite bowl simultaneously lowers itself, thus creating a solid cylindrical ingot of silicon around the seed crystal. The ingot might be larger than the desired diameter, but it can be trimmed to a desired size.

Large-sized ingot would not do us any good. Therefore, the ingot is sliced into thin layers using a 100-200-micron thick high-grade steel wire connected to rotating rollers cuts the ingot into roughly-surfaced wafers. To remove the rough surfaces several wafers are lapped on both sides in between to counter-rotating pad, this is called ‘lapping’. Though lapping helps to smoothen the surface of the wafer, it degrades the crystal structure of the silicon surface of the wafer. However, a process called ‘etching’ is employed to restore this and improve the crystal structure. Etching is done by immersing the wafer into any suitable etchant such as; KOH or HF.

The surface of the panel is then polished using an ultra-fine slurry to obtain a smooth wafer.

Having discussed how the various Crystalline panels are made we have a good ground to discuss the major differences between them. As we move on we would consider different points in analyzing the two types of technology.

Monocrystalline VS Polycrystalline Solar Panels

In the previous sections, we have gone through all of the processes required to make a crystalline solar panel, we shall proceed to analyzing several points that must be considered in placing proper value on each solar panel.

At the end of this section, you would be able to identify what solar panel is best for you based on their characteristics.

●     Appearance Difference

How the different panels are made contributes to how they eventually look.

For instance, the monocrystalline panel is made out of a single crystal of silicon and thus it has a uniform color throughout the entire material. Whereas, the polycrystalline panel would have varying color differences across the entire material due to the fact that its ingot is gotten from several crystals of silicon.

Most times monocrystalline panels are black or dark blue in color and each cell (finished wafer) has a rounded edge. Do not forget that we have seen that the ingot obtained from melting the silicon rocks looks like a rounded cylinder and thus the individual wafers originally are rounded and needs to be cut into square shape to meet up with the required standard, but this would waste a whole lot of the monocrystalline silicon.

Therefore, it is then cut so that, part of the rounded part of the circular wafer does not waste. Hence, the reason for its rounded edge.

Polycrystalline panels have a bluish color and appears as though there are particles (looks more like rocks) are present inside the panel. Each cell has a square shape because it was cut out of a square shaped ingot.

●     Module Convert Efficiency

How efficiently the panels would be able to convert solar energy into electricity greatly depends on the molecular structure of each material.

The monocrystalline panel because of its consistent make-up allows electrons to flow freely, but the polycrystalline would not as much as a monocrystalline panel would owing to the same reason of molecular structure. The conversion efficiency of the monocrystalline panel is from about 15% to about 20%

●     Temperature Factor

The conversion efficiency of the panel also depends on the temperature, such that an increase or decrease in temperature above a threshold of 25oC causes an increase or decrease in the efficiency of any of the panels (be it monocrystalline or polycrystalline).

However, how much temperature affects the efficiency of the panel (temperature coefficient) varies between different brands e.g. a certain type of panel may have a temperature coefficient of about -0.123% per oC which means for every increment of 10C the efficiency reduces by 0.123%.

It has been observed that generally polycrystalline panels can withstand more heat than the monocrystalline panel

●     Shading Factor

No solar panel works well when it is completely shaded. However, because of some particular reasons the monocrystalline panel functions better in cases where there’s no extreme shade.

●     Cost

The monocrystalline panel costs more than the polycrystalline solar panel. This is due to the cost of producing the mono panel which costs approximately 20% more than the cost of production of polycrystalline panel.

The cost of production of mono panel is more of a function of the wastage procured during the reduction of the shape of the ingot to a rounded square shape.

●     Space Efficiency

If you need a panel that efficiently converts and you’re willing to trade cost for space, the monocrystalline panel is your best bet. Though it’s not impossible to get polycrystalline panels of the same efficiency as a mono, but since the conversion efficiency of the polycrystalline panel is less one would need a large poly to match the required efficiency.

So, for less space and great efficiency the monocrystalline panel works well.

Conclusion

Let’s look at a summary of what was explained through this post, you can choose based on your need.

Pros Cons
Monocrystalline PV panel
  • They have very high conversion efficiency
  • They also have high space efficiency
  • They perform better in shady places than a polycrystalline panel would.
  • They are very costly to produce and to purchase
Polycrystalline PV panel
  • They have a relatively low cost of production and hence, are cheaper to purchase
  • They have proved to have more heat tolerance than monocrystalline panels (though very minute)
They tend to be large and may not be used in houses with small space

They have. a small conversion efficiency compared to that of monocrystalline panel.

References

http://www.madehow.com/Volume-1/Solar-Cell.html

 

Peak Sun Hours: Important Factor of the Average Daily Solar Insolation

Peak Sun Hours

Peak Sun Hours, Source: www.pveducation.org

In the course of designing an off-grid solar street lighting system, you’re often faced with an initial challenge of factoring the Peak Sun Hours of your location to experience maximum energy from your solar PV system.

If you’re not a PV technical personnel, understanding the peak sun hours and factoring it could be a difficult task.

But,

Not to worry, in this post we’ve made the process as simple as possible for you to understand and apply the same to your PV installation.

To start,

Let us take a clear look at the term itself.

What is Peak Sun Hours?

In simple terms,

Peak Sun Hours is the number of hours in a day when the Sun is at its maximum radiation.

The value of PSH varies per location, this is due to some certain factors that will be discussed shortly.

Before then, let’s break down the technicalities; because there’s more to the definition.

Average radiation from the sun measured on the surface of the earth during a clear day or noon is about 1000W/m2. (This value is standard for all PV tests & measurements.)

The number of hours in a day that a location experiences this value of radiation is called Peak Sun Hours.

1 Sun Hour is equivalent to 1000 W/m2 of the sun’s radiation collected in 1 hour.

3 Sun Hours is equivalent to 1000 W/m2 of the sun’s radiation collected in 3 hours.

The unit of measurement is therefore kWh/m2. It is also expressed as kWh/m2 day, this refers to the total Peak Sun Hours in a day.

As stated earlier,

Based on your location, there are couple of factors that affect the value of the Peak Sun Hours.

What are they?

Factors that Affect the Peak Sun Hours of a Location?

It is important to note that your PV module has no effect on the Peak Sun Hours, rather, the factors are more environmental.

The 3 major environmental factors that affect the Peak Sun Hours include:

1.   Position relative to the Sun:

Regions of the world that are closer to the equator have more intense radiation from the sun compared to those further away from the equator. The Peak Sun Hours is more in those regions closer to the equator.

Therefore, if you’re installing a solar power system in these regions, you’d have more energy produced from the solar PV system and vice versa.

2. Cloudiness

The presence of clouds in the atmosphere diffuse the solar radiation, thereby reducing the Peak Sun Hours. The cloudiness of a location is more of a daily factor; where rainy or cloudy days have less PSH, and clear days have more PSH.

3. Climatic Seasons

During some seasons, PSH is bound to reduce based on the sun’s position on those times. For instance, there’s more Peak Sun hours during summer seasons compared to winter seasons.

Knowing the PSH of your location is very important when installing a solar PV system. This would allow you to estimate the energy the PV system can produce maximally.

To estimate the energy your PV can produce, follow the simple steps below.

How to calculate the Energy produced by your solar system using Peak Sun Hours.

In 2 simple steps, you’re done.

Firstly, determine the power rating of your solar PV system.

Then you multiply the value by the PSH of your location. This gives you the estimate of the total daily energy that can be produced by your solar PV system.

For example,

Suppose I install a solar PV system of 5 m2 in California, where the PSH is 5.5 kWh/m2, the total energy the system can produce daily is

5 (m2) × 5.5 (kWh/m2 day) = 27.5 (kWh)

The higher the PSH, the greater the energy produced from a solar PV system.

What if your location has a low PSH, what do you do?

How to improve your solar PV energy production for low Peak Sun Hours Areas.

Even during cloudy days, your solar panel would still produce power only that it would be about 25-40% less than the expected. To minimize this, the following can be adopted:

  • Use solar modules made for low PSH regions, they are usually designed with greater efficiency.
  • Use a sun tracking solar panel.
  • Tilt the angle of PV module to effectively capture the sun’s radiation based on your location. This is the most popular solution used for areas with low PSH. Depending on your location, the angle optimum angle is calculated relative to the latitude, which now determines the angle the PV modules will be tilted.

You might need the service of a technical personnel on this method.

To round up, we’d share a couple of online resources that would help you to determine the PSH of your location.

Available Online resources to know the peak sun hours for my location.

For locations in America, these resources can be very helpful to determine PSH of your location

For locations in Europe and Asia, the link below would help in making several solar calculations, including the optimum tilt angle for your location.

For locations in Australia, this document would give adequate information to the PSH values of your location.

Other helpful resources for other cities can be found in the link below. You can also check this link to help in estimating the optimum tilt angle for your PV module.