Solar panel is a very green way to make electricity for home, and now it is getting cheaper than ever but sometimes, the number of electricity generated from your solar panels can be disappointing. It depends on panels efficiency and the power output under weather condition and the ways you installed.
So, in this article, I’m very happy to show you how to get the most electricity from your solar panels. Try to follow my guide to get as much electricity as you can – This is a table of content:
- What factors affect the electricity output?
- How to put panels to get the most electricity
- Making array with more than one solar panel to get more power
- How to mount panels to get the best result
Because, the most important thing of making electricity from solar panels is the sun, so we will discuss Sun first.
How about the sun?
The sun not only moves from east to west during the day, it moves north and south with the seasons. The sun is furthest north in June when it rises to the north of due east and sets to the north of due west.
In December it is the furthest south and the sun rises to the south of east and sets to the south of west. On 21 March and 21 September the sun rises exactly in the east and sets exactly in the west. The sun is always at its highest at noon. Its height at noon depends on the time of year and how far the site is from the equator.
When installing solar panels in the tropics, remember that sometimes the sun is in the northern sky and sometimes it is in the southern sky. A location that may be in the sun all day in June may be shaded all day in December.
What factors affect the electricity output?
Effect of solar panels surface?
Just as a large roof collects more water than a small one, the larger the solar panel, the more electricity is produced. If you double the amount of surface covered by panels, the electricity output is doubled.
“The larger the panel, the greater the electricity produced”
Effect of sun’s brightness
The harder it rains, the more water you obtain from a roof. PV panels work the same way with the sun. The more sunlight that falls on the panel, the more electricity is produced. If there is shade on a panel, the electricity output falls greatly.
Effect of panel direction
If you stand in a rainstorm with a strong wind blowing, the side of you facing the wind gets much wetter than the side away from the wind. To get the most electricity from a solar panel, it must be facing the sun.
How to put panels to get the most electricity?
1. Make sure that the brightest sunlight falls on the panel
The brightest sun is where there is no shade. Solar panels lose most of their electricity output when even a small part of the panel is in the shade. It is very important that solar panels are placed where the sun will shine on them from at least 09:00 to 15:00 without any shade at all. Always remember that the sun shifts its position from north to south over the year as well as from east to west during the day.
In the tropics, the sun will be more in the northern sky for the months around June and more in the southern sky for the months around December. So you must pay attention to trees and buildings both to the north and south of the panel and make sure they will not cause shade at any time of year.
2. Make sure that the panel faces the sun
Most electricity will come from the panel when it points directly towards the sun. But because the sun moves across the sky from morning to night, the panel would have to move to always face the sun. This is not practical in most places and the best we can do is to fix the panel facing in the direction where the sun is located when it is brightest.
The sun is brightest at noon. The location of the sun at noon depends on the time of year and how far you are from the equator. The best mounting for a solar panel is with a tilt towards the equator equal to the latitude of the location. Thus a panel located at a site with a latitude of 12 degrees north of the equator should be mounted with a tilt of 12 degrees facing towards the south.
A panel located at a site with a latitude of 18 degrees south of the equator would be best mounted with a tilt of 18 degrees towards the north. A panel mounted on the equator should have a tilt of 5 degrees towards any direction. A small tilt of 5 to 10 degrees is always needed to let the rain wash off any dirt from the panel.
In the tropics when the latitude is less than 15 degrees, you do not have to be highly accurate in pointing the panel towards the equator. At latitudes higher than 15 degrees, the panel needs to be carefully pointed towards the equator to get the best power output.
3. Keep the panel as cool as possible
I have written about this once, in this post: 7 common mistake everyone makes when build solar PV system that solar panels designed to run cool, they don’t like heat.
Because solar panels must be in the bright sun, it is difficult to stop them from getting hot. It helps if solar panels are mounted so that the wind can blow over both the top and bottom of the panels. That means they should not be mounted directly on a roof but at least 0 cm above the roof, so that air can move all around the panels and cool them.
Making an array with more than one solar panel to get more power
Most people want more power than a single solar PV panel can provide. To increase the power available, panels may be joined together. Panels can be connected in two ways: series connections or parallel connections.
1. Series-connected panels
When more voltage is needed than a single panel can provide, additional panels are connected in series. If one panel provides 22.5V, two in series will provide 22.5 + 22.5 or 45 V. Three in series will provide 67.5 V. For every 22.5 V panel connected in series to other 22.5 V panels, the voltage will increase by another 22.5V.
The amount of amperes provided by panels in series is the same as that provided by one panel because the same electricity flows through all the panels, as they are connected in one long line. Each panel increases the electrical pressure but the flow stays the same as with one panel. As power in watts equals volts times amperes, the power increases as panels are added.
Two panels are connected in series by connecting the positive of one panel to the negative of the other. The result is doubled voltage but the same amperage as one panel.
2. Parallel-connected panels
When the voltage from a single panel is the amount needed but there is not enough current, panels can be connected in parallel. If one panel provides 2 A in bright sunlight, two in parallel will provide 2 + 2 or 4 A. For each of these 2 A panels connected in parallel, an extra 2 A will be produced in bright sunlight.
With parallel-connected panels, the voltage remains the same as with one panel but the amperage increases with each additional panel. As power in watts equals volts times amperes, the power increases as panels are added.
Note that for both series- and parallel-connected panels, the power increases as the number of panels is increased. Two panels in parallel produce the same power as two panels in series, but the voltage and amperage are different
Two panels are connected in parallel to connecting terminals of the same polarity. The amperage is doubled but the voltage is the same as one panel.
3. Series-parallel connections
Solar PV systems to power refrigerators and other large appliances often use a 24 V battery instead of a 12 V battery. Some even use 48 V batteries. As solar panels are almost always designed to charge 12 V batteries, two panels have to be connected in series to charge a 24 V battery and four panels have to be connected in series to charge a 48 V battery. Often more amperes are needed than one panel can provide, so panels have to be connected in parallel as well. This combination of series and parallel connections can be extended to as high a voltage as needed by adding more panels in series and as high an amperage as needed by adding more panels in parallel.
There are many different ways of connecting a large number of panels correctly to get the desired voltage and amperage. You can connect panels in series until the voltage is reached then connect more series-connected sets of panels in parallel until the amperage is reached.
You can also connect panels in parallel to get the amperes needed then connect more parallel-connected sets of panels in series to get the desired voltage. Perhaps this should be called a parallel-series connection, but it really does not matter because the final voltage and amperage are the same as in a series-parallel connection.
If you have panels with different characteristics
■ Series connections
If PV panels with different voltage and current (amperage) characteristics are connected in series, their voltages should be totaled just as when identical panels are connected in series. So if one panel that produces 16 V and another that produces 17 V under the same conditions are connected in series, the resulting voltage is 16 + 17 = 33 V.
However, the current available at maximum power will be limited by the panel with the lowest ampere capacity. Series-connecting a panel that by itself can produce 2 A with another that by itself can produce 3A under the same conditions will result in a current of just over 2 A from the two panels. This means that to get the most out of series-connected panels that are not the same, the closer their ampere rating match, the better the performance of the pair will be. As amperes are determined by the size of the cells, panels connected in series work best if the cells on both panels are the same size.
■ Parallel connections
If PV panels with different voltage and current characteristics are connected in parallel, their currents should be totaled just as when identical panels are connected in parallel. So if one panel produces 3 A and the other produces 2 A, the two in parallel will produce 5 A.
However, the voltage available at maximum power from the parallel-connected panels will be limited by the smaller of the two-panel voltages. Parallel-connecting a panel that produces 16 V with one that produces 17V under the same conditions results in a voltage a little greater than that of the 16 V panel. Thus, to get the most out of parallel-connected panels, they should have the same number of cells and produce about the same voltage.
Importance of good panel connections
All electricity from a photovoltaic system comes from the panels. If the connections to the panels are not clean, tight and properly made, some electricity will be lost and the system will not provide as much energy as it should.
Always be particularly careful in making connections at the solar panels. Use only screw terminals and make sure you use lock-washers on the screws so that they cannot loosen over time.
How to mount panels to get the best result
Because solar panels are constantly exposed to wind and weather, it is important that their mounting is secure and resistant to corrosion or loosening.
Mounting panels on a roof is usually cheaper than mounting them on a pole. But if the roof is shaded or facing the wrong way, a pole must be used. Pole mounting provides better cooling for the panels than roof mounting. Cooler is More!
Pole-mounted panels usually have to be placed further from the battery than panels mounted on the roof, so will need larger wires to stop too much power loss through the wiring.
The poles should be tall enough to prevent people from touching the bottom of the panels. Burying the wires is usually better than stringing them overhead, but make sure they are designed for underground use. The panels should be attached with stainless-steel bolts or screws, not nails, which can loosen over time. If the panels are mounted on a pole, it should be set securely in the ground and anchored to a building if possible.
We have 3 basic rules to get the most electricity from your solar panels:
- Rule 1: There should be no shade on the panel between 09:00 and 15:00.
- Rule 2: Tilt the panel at an angle equal to the latitude of the site, though it should never be tilted less than 5 degrees from horizontal. The panel should face north for sites south of the equator and it should face south for sites north of the equator.
- Rule 3: Mount the panel at least 10 cm above other surfaces so air can easily cool the back of the panel.