How to install solar panels?

With the rising oil prices, and the ongoing technological advances in the solar panel industry, it becomes real interesting to invest in solar panels. In this article I will guide you from the first steps of choosing which panels and the costs of your own solar energy system, to installation and monitoring your solar panels.

Before you can start searching for the possibilities of a PV system on your roof I will start with some basics.

Theory behind PV-panels: Solar panels use photons (small parts which are travelling with the speed of light and have no mass) which are emitted by the sun to generate electricity. The more photons to hit the panel, the more energy you will produce. This process is called the photo voltaic effect, this is where the name PV comes from.

Panel efficiency: Unfortunately it is not possible to possible to convert all of the suns power to electric energy. Nowadays about 25% can be converted, how higher this efficiency the more electric power you will harvest.

Parts of a PV-system: Off course you need solar panels for a PV system but aside from the panels other equipment is required. A complete PV-system contains multiple components:

Solar panels: The solar panels convert the suns solar energy to electrons which are electrical energy. Most of the time a PV-system contains a string of three solar panel, but it is possible to use up to fifty solar panels in a string in industrial size installations. This depends on the amount of energy you want to deliver.

Mounting: Off course the panels need to be mounted to the roof. There are multiple DIY systems to install the panels on a flat or sloping roof.

Inverter: Because the solar panels produce around 90 Volt this first needs to be converted to your local net voltage. In this process there also is an loss of efficiency of around 5% depending on the type and temperature of your inverter. Make sure the inverter is installed in a cool and dry room.

Cables: Because the solar panels are on the roof and the inverter is hanging inside your house you will need cables to connect them. These cables will also ''use'' some power due to their resistance, the bigger the diameter of the inner cable and the shorter they are less the energy will be lost in the cable. A normal cable with a length of 10 meters will result in a loss of about 0,25%.

Because not everyone is used to using physical quantities I will explain some basics.

Because electric energy is something you can not see it is hard to imagine how it works. To make it a bit simpler I will compare electric power running threw a wire with water threw a river.

Voltage: This gives the difference in potential between two points. So on one side there is a negative load and on the other side a positive. How big the difference between these loads is the higher the voltage. It can be compared with the difference in level in a river. It determines the direction the electricity flows like a difference in height in a river determines the direction it flows.

Current: Current is the amount of elektrons which passes on a certain point. This can be compared with the amount of water which passes in a river.

Resistance: Resistance can be compared to the width of the river. Threw a wide river a lot of water can move fast but threw a small river it is hard to move a lot of water.

Power: With the flowing water in the river a water wheel can be powered. This can be compared with the power an electrical appliance uses. So with a lot of flowing water the wheel will spin fast so there is a lot of water, so a high current will result in a high power. And with a big difference in level the water will flow fast and the wheel will spin fast.The unit for power is Watt.

Watt: Watt is the amount of power per second which is used (Joules per second). For example: a light bulb used 60 Watt which is quite low and a vacuum cleaner uses op to 2500 Watt which is real high.

kWh: Kilowatt Hour is the way the amount of energy you use in a period is measured. It is based on the amount of Watts you use in one hour. So if the vacuum cleaner of 2500 Watts runs for one hour 2500 Wh is used, divided by 1000 because it is in kilo's it is 2,5 kWh.

Wp: Because the amount of power which is produced by a solar system is depending on the amount of sun. The number of watts which are produced are proportional with it. For the maximum amount of power the Watt-peak(Wp) is used.

Two important things which will influence the time until you reach the break even point are the location and angle.

Choosing a location:

There are certain important parameters which will influence the amount of energy solar energy can harvest in a year. Because the ultimate angle and orientation are depending on your location on earth there is no correct angle for everyone. To illustrate I will use Amsterdam in this example. Based on that also the angle of the solar panels on other places on the earth can be calculated.

Shadows:

Because solar panels are much less effective when they are in the shadow of - for example - a tree or a building it is advised to find a spot where there is direct sun light. When the sun is low during the winter the radiation is low so when there are some shadows at that time of year it is not much of a problem. But make sure the panels can make as much use as possible from the strong sumer sun. If it is safe you can sit on the roof and look to the sky to so any possible obstructions.

Solar orientation:

Because Amsterdam is on the northern hemisphere the sun rises in the east and sets in the west. When the sun is at the highest point it is in the south. So you want the panels to be orientated to the south. When you are on the southern hemisphere you want the panels to be orientated to the north.

Angle:

The angle between the sun and the panels should be zero degrees for maximum performance. Because the panels usually are static you need an average for the entire year. Depending on the latitude the angle angle of the solar panels can be determined by using the graph below. There are special installations with a energy efficient engine which will make the solar panels follow the orbit of the sun. This gives a higher return from your panels but normally is another large investment.

The choice of size of your PV system are based on space, local legislation, personal preferences and budget.

Amount of Wp

The number of solar panels you need is depending on the amount of kWh you want produce and that is depending on the amount of Wp. On average the amount of Wp you have is the same as the amount of kWh you will produce in one year. So if you want to produce 1500 kWh you need approximatively 1500 Wp. Solar panels normally are produced with peak wattages between 50 and 250 Wp. For the example is it possible to use six 250 Wp panels.

Space

The first important thing to check if you have got enough space on your roof or garden to install the solar panels. Find this spot with the information on shadows and angle taken in to account. For calculations 125-150 Wp per m² can be used.

Legislation

In some country's there is special legislation on producing your own energy. Always check if there are any subsidy's for solar panels in your country or state.

To calculate your system you can use this Mastervolt system calculator:

http://images.mastervolt.nl/files/mastervoltpvsystemcalculator.xls

Chinese panels

There are a lot of manufacturers of solar panels, all with different quality and prices. In recent years there are a lot of Chinese panels on the market, they are a lot cheaper but this goes at the expense of the quality. So I always recommend to buy solar panels from large manufacturers like Kyocera.

Some final tips when you are going to purchase the system.

Internet

The prices for the complete system are quite high so it is always recommended to look around on the internet and find the lowest prices. Also a lot of advice on which brands or which good combination of inverter and panel can be found.

Inverter

Also the inverter is real important. Always try to find an inverter which is within the Wp of your solar system. Another important tip is when your system is over 600 Wp you need a separate group in the fuse box for only the solar system.

It is possible to install the system yourself or let an installer do it for you. Most of the systems are DIY so you don't need any electrical knowledge. Always take the time to install the system and think twice about all the steps you take. If all is well the system will stay there doing its job for more then 25 years.