Solar Energy

Solar Energy FAQs



Are we collecting the data from all the schools?

The electricity generation data from the solar panels installed in Schoolgen schools is collected by a device call the "hot-e box" and sent to the Schoolgen website via the world wide web.

Each Schoolgen school can see the electricity that is being generated by their solar panels on a daily, weekly, monthly and yearly basis on the Schoolgen website here.

The diagram below shows how this system works.

Technical Diagram: How Schoolgen solar data collection works.

How does the solar panel absorb sunlight?

A solar module actually absorbs Photons that are carried in sunlight or solar radiation.

These photons hit the solar module and are absorbed by a special Semiconducting material called Silicon (Si).

The photons that have been absorbed then crash into Atoms and knock the negatively charged Electrons loose from the atoms. At the same time positive charges or Holes are created. These holes actually flow in the opposite direction to the negatively charged electrons.

This allows the electrons to flow through the silicon semiconductor, which produces electricity.

How long do the solar panels last?

Solar panels are made to last a very long time. They are guaranteed to generate power for 20 - 25 years.

In general solar panels are expected to last 30 to 40 years!

How advanced is PV technology?

Photovoltaic's, or PV is cutting edge technology.

Every year there is lot of research done on solar power to help make it bigger, better, cheaper and stronger!

The idea of solar power (or more correctly the theory behind it) was introduced in the 1800's.

It took until the 1940's and 50's with advancements in semiconductor process to enable PV to become a commercial reality.

Since then it has gone from mainly being used in space to being used in many, many applications from powering schools to assisting remote communities to generate power - using glass panels on the exterior walls of high rise building as well as smaller items such as watches, calculators and even milkshake machines!

It is fair to say we are only half way there!

What is the future for solar panels?

The sky is still the limit when it comes to the future of solar panels.

Advances in photovoltaic technology are happening all the time. Some of these are very small advancements but they do help increase the performance of the solar panels and most importantly also reduce the cost.

One day in the not too distant future nearly every house and building will have some form of solar power.

Does it matter what the weather conditions are like?

Yes. Solar panels work best under direct sun. So on a nice sunny day the solar power system will definitely produce more power!

What are the environmental impacts of using solar panels?

During Manufacture

PV manufacturing is energy intensive, resulting in emissions that accompany the use of standard grid electricity. Emissions from manufacture differ for the same PV panel according to the energy mix that is used for generating electricity in that particular location.

It generally takes between one and six years for a PV system to generate the amount of energy equal to that used in production.

Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel based electricity generation technologies.

For further information about then environmental effects of photovoltaics please email info@schoolgen.co.nz.

During Operation

Solar panels do not produce any fumes, gases or noise when they are operating so they do not present any environmental impact while they work.

As there are no pollutants and no moving parts (none that you can see anyway!) Solar panels are not dangerous to birds or other animals in the environment and they are not harmful to people.

Keep in mind that solar panels are made to generate electricity. The solar panels are made to be VERY safe however, electricity can be dangerous so never touch a solar panel without an adult around!

What can you do with 2kW of power?

The power consumption of a device is equal to the length of time it is on, times the power it draws - e.g. a television that is rated at 100W is left on for 4 hours it will consume 400 Watt / hours. Here is a list of some common household appliances and how much power they use.

  • 1500 Watts - Microwave Oven
  • 1500 Watts - Toaster
  • 140 - 300 Watts - Desktop Computer + 17" Screen
  • 45 Watts - Laptop Computer
  • 60 - 100 Watts - Incandescent Lightbulbs
  • 18 Watts - Compact Fluroescent Lightbulbs

So the 2kW of power generated by the solar panels is a useful amount of power.

  • That's about 15 computers all at once
  • Or 15 42-inch LCD TV'S!

The solar power system is made to deliver a continuous amount of power when the sun shines.

Every time we generate 2kW of energy for one hour we are producing 2kWh.

What is a solar panel made up of?

Photovoltaic modules are made up of the following components:

  • Silicon made in to Solar Cells
  • Special light absorption coating
  • Solar Glass
  • Plastic (or glass) backing material
  • Electrical connection cable
  • Metal Aluminium frame

These are assembled in a special process to get a solar Module or panel as follows:

Silicon (Si) is refined in a special process to create a special Semiconductor material (like computers chips) called Solar Grade Silicon.

This is melted down and formed into solar Wafers.

The wafers are then put through a special wash to give them special layers (P and N doped layers) then a special light absorption layer. This gives the cells the blue colour.

Then electrical contacts are applied to the wafer to allow the flow of electrons. We now have a solar cell.

At this point every cell is tested under a special light know as a flasher or artificial sun. The flasher powers up the cell as though it was exposed to intense sunlight and lets the scientists make sure every cell is ready to go to work.

Once tested, several cells are then connected electrically to form Strings of cells. This is what determines the power of the solar module.

The electrical connections of each string of cells are then all joined to two points known as the POSITIVE (+) and NEGATIVE (-) Poles.

The strings of cells are now placed on special highly transparent Glass (low iron - high Transmisivity/ low reflectance glass).

A protective backing is then applied. This may be another layer of glass or more commonly a special plastic type layer called Tedlar.

A special box to keep the electrical connection point is glued in place over the positive and negative connection points. This keeps the solar module and electrical connection points all waterproof and is called the Junction Box.

Finally, a strong Metal Frame is fixed around the outside of the module to give it strength and to make it easier to mount. This is typically made from aluminium as it is both strong and light.

Now we have a complete solar module!

This is then run through a tough testing process to check electrical performance and ensure it is waterproof.

Ready to use for 40 years!

What is the difference between photovoltaic's and solar hot water systems?

Photovoltaics use the photons in solar radiation to excite Electrons to create Electric power.

This simply means they use the LIGHT in the solar radiation.

Solar thermal collectors that we use in solar water heating use HEAT generated by the solar radiation to heat water.

Solar thermal collectors use the "Greenhouse Effect" by placing a special layer of absorption material under a glass cover. The glass allows the visible and ultraviolet spectrum light (High frequency or Short wave light) in solar radiation through, however it does not allow the reflected lower frequency infrared radiation (Long wave light) to escape, so it is absorbed. Once the heat is absorbed it may be moved in the water or fluid from one place to another such as from the collector on the roof into a water cylinder.

Where is the best place to locate the panels and why?

Every morning the sun rises in the east and moves over our heads, through the northern sky to the west where it sets each night.

This means that (in the southern hemisphere where New Zealand is located) north facing gets the most sun of the day in summer and winter.

Because the NORTH get the most sun we face the solar panels NORTH to catch as much sun light (or sun light hours) as we can on any given day.

What are the costs of a solar panel? Is it cheaper than normal electricity?

Solar panels are not cheap to buy.

Imagine if you go to the shop and buy one bottle of milk.

Now imagine if that one bottle of milk never needed replacing. Every time you left it in the fridge for 4 hrs and opened the fridge there it was. Full to the top with nice fresh milk!

Now think what if it was the best milk you could get. The bottle is filled with not only the freshest milk but it comes form the happiest cows. Even better we never need to throw away the bottle because it is never empty! That's saving a lot of plastic!

A solar power system is similar to the bottle of milk.

When you install a solar power system there are very little on going costs (usually none). This means you are then getting FREE electricity! Imagine that you don't pay for the electricity generated by solar power systems for many many years!

Even better the electricity generated by a solar power system is kind on our environment and kind on our planet.

So like the bottle of never ending milk we have no waste and pollution, only clean fresh power.

When we produce "normal" power or power for the national power grid - it is generated to make sure we can make it affordable for everyone. Sometimes this means we need to use what is the cheapest source of fuel to get the power we need, or to make sure there is enough power to go around.

This means we sometimes must use fuels that produce emissions or pollutants but it also means we have cheaper power.

Solar power is clean and green but it also more expensive than normal mains power.

Can you use the solar energy at night?

Solar energy systems only generate their energy when the sun shines.

At night, when the sun goes down the solar power system will rest waiting for the next day's sun.

When the sun comes up it starts work again.

If we want to use power at night that has been generated during the day by the sun we need to store this energy somewhere. Kind of like storing water when it rains in a tank or bucket for when we need it.

We can store this energy generated from the solar panels in BATTERIES.

That means when the sun is not shining we can still use power we have stored during the day.

Batteries are not used in the PV systems in the Schoolgen programme so the panels only work during the day.

Does the energy output change when it is a cloudy day?

Yes. On a cloudy day the output of a solar system is less than a bright sunny day, however the system will still generate some power.

Have a look at one of the Schoolgen school's daily electricity generation data reports here and compare with the weather for that area and see what difference the weather makes!

Can you put them on your house?

Yes. Solar panels are used in all kinds of places.

They can be used on almost ANYTHING like houses, bus stops, camper vans, boats, signs, lights, billboards, parking meters and even high-rise buildings!

In the future many buildings will have solar power for electricity and heating.

Keep an eye out for solar panels on top of speed warning signs by your school. They are there!

Are solar panels enough to save the planet?

Every day we get enough energy from the sun to power what the whole earth uses in an entire year!

It would be possible to power the earth from the sun but we need to do a LOT MORE to help us save the earth.

First we need to make the most of what we have already and make sure we use it wisely.

If we all start with some simple steps we can go a long way to helping save our planet.

Some things you can do around your home and school to help save the planet are:

Think twice and reduce your power consumption - If you turn something on remember to turn it off when you're done. It is much easier to save power than it is to generate more power.

Use the same shopping bags when you go shopping. This will help to reduce the amount of plastic waste we all produce.

Think about using items with less packaging and buy things that have recyclable packages. When you have finished using it, recycle it!

Don't forget: Reduce, reuse and recycle.

That's the most important first step for us all to take to help save our special planet.

Can the electricity generated by the solar panels be stored?

Yes. If you think of rain and then imagine you catch rain in a bucket while it is raining.

One day when there is no rain you can go to your bucket and use the rain (water) you have stored for things like a drinking or washing your hands.

The power we get from solar or wind can also be stored. The difference is the type of bucket we use to store this energy is a little bit different! We call these BATTERIES.

Batteries are able to hold the power (like the water in our bucket) so we can use it when we need it for things like lights or computers or anything else that need power.

That means when the sun is not shining or the wind is not blowing we can still use power we have stored during the day.

How does the electricity get from the panels to the National Grid?

Solar panels generate in DC or Direct Current.

DC or Direct Current looks like this: =

However, the National Grid and most things plugged into it (like your school and your house and your parents work) use AC or Alternating Current.

AC or Alternating Current looks like this: AC Current

So First thing we need to do is convert this DC Current into AC Current.

To do this we use a special type of converter called an INVERTER.

The inverter takes the DC from the solar panels and converts it to AC for use in the home, school or for EXPORT to the national grid.

An inverter looks something like this:

Bayswater Inverter

Inverter Diagram

AND just when you thought that was special

The inverter also "looks" at the national gird and takes a record of what the power on the grid is dong. This means the inverter can then make sure it delivers the exact same power as what the grid needs.

If you really must know what actually happens is the inverter measures the VOLTAGE and FREQUENCY of the grid and then SYNCRONISES with this to make sure it delivers the exact same VOLTAGE and FREQUENCY as the grid.

SO: We have converted the DC from the Solar modules into the AC we use, and the inverter also made sure its matches the grid.

NOW: When the sun shines the inverter will supply AC power where it is needed.

If we do not generate enough power from the solar power system then we simply get our power from the grid. Just like we do now. This simply mixes with the solar power we have generated so we can reduce how much power we bring in from the grid.

This is called IMPORTING.

Will the PV system installed in Schoolgen schools be exporting electricity to the National Grid.

The PV system that is installed in Schoolgen schools can generate a total capacity of 2kW.

When the PV system was designed for the Schoolgen programme it was assumed that the PV system would never be in a position of generating more electricity than a school would be using at any given point in time (excess electricity).

Therefore Schoolgen schools do not have an import/export meter installed. (Import/Export meters tell us how much electricity is being used (import) and how much electricity is being sent out to the grid (export)).

Where are the panels made?

Solar panels are made in many countries around the world.

A company called Schott Solar in Germany makes the solar panels we install on schools.

We use these panels because the process for their manufacture requires very little energy; they are made to catch lots of sun and to last a long time.

That's important to us because we don't want the solar panels to cost the earth and we also want to be able to see them working hard, long after you have left school.

How is the electricity generated by the panels used within the school?

The energy produced by the solar panels is introduced to the school distribution network as and when it is produced. Given that this is generated inside the schools distributed AC network it is used prior to and in conjunction with any "imported" energy.