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How to Install

The Femtogrid Solar System is easy to install as its 4 components are plug&play. It consists of:

Together with PV modules and the PV mounting system the Femtogrid Solar System forms a complete PV system. The installation of the Femtogrid Solar System must be carried out by authorized installers and the installation sequence for the 4 components starts after the mounting has been put in place.

 

Practical notes

1. The installation sequence is described for the installation of the Femtogrid Solar System connected to solar DC input of 2550 Wp. This is the DC input that we recommend to connect to one Inverter 2400. As a result, one Inverter 2400 is used in the installation described below.

2. The Power Optimizer is mounted behind every module used in the PV installation and the Power Optimizers are subsequently connected in parallel to the inverter using the 3 core DC cable 2,5 mm2. The type of solar panel, manufacturer, and aging is allowed to be different for these solar panels connected to the Femtogrid Solar System, as long as:

  • the modules are mono- or polycristalline and
  • the power output of the module<300 Wp and
  • the open circuit voltage of the module @ -20 degrees celsisu<42 V

As our first version of the Power Optimizer is designed for these types of solar panels. Together the solar panels, the Power Optimizers behind the solar panels, the 3 core DC cable and the inverter form the DC side of the installation.

3. Numbering the Power Optimizers on the rooftop, start with the mounting the Power Optimizer behind the solar panel that is mounted most distant from the inverter. This is the first solar panel and is connected to the first Power Optimizer. Continue the logical numbering of the solar panels, when working towards the inverter. This eases the traceability of the solar panels and the Power Optimizers once the installation has been completed. Following this line of reasoning the last solar panel and the last Power Optimizer is the one most nearby the inverter.

4. Let's start the installation with an important safety precaution:

Do not connect the custom length DC cable running from the modules on the rooftop to the inverter placed inside until every solar panel is connected to its Power Optimizer and all Power Optimizers, in turn, are connected in parallel to each other. 

 

The brief how to install

The sequence of the installation of the Femtogrid Solar System is as follows:

  1. Attach the Power Optimizer behind every solar panel.
  2. Mount the 1st solar panel on the rooftop and connect it to the 1st Power Optimizer.
  3. Mount the 2nd solar panel on the rooftop and mount it to the 2nd Power Optimizer. Connect, in turn, the 1st Power Optimizer to the 2nd one.
  4. Mount all other solar panels on the rooftop, connect each solar panel to its Power Optimizer, and connect all Power Optimizers in parallel to its next one.
  5. Connect the custom length DC cable to the last Power Optimizer and pass it through a hole to the inside where the inverter is placed.
  6. Mount the inverter inside and connect the custom length DC cable. All solar panels are now connected in parallel to the inverter and the DC side of the PV system is ready.
  7. Connect the inverter to the mains. Now also the AC side of the PV system is ready.
  8. Power up the PV system.
  9. Mount the Monitoring Box next to the inverter and activate it.
  10. Check the PV system and its power generation on the display of the inverter.
  11. Complete the installationform. The installation of the PV system is now completed.

The in depth installation sequence is presented for each component below.  

 

The in depth how to install

 The in depth installation sequence uses pictures to ease the installation and describes the sequence per component:

 

1. How to mount the Power Optimizer behind the solar panel

The heart of the Femtogrid Solar System is formed by the Power Optimizers that are mounted behind every solar panel. The smart electronics inside the Power Optimizer boost the power generation of the solar panel.

1-1. Consider the mounting of the solar panel: is it portrait or landscape?

1-2. Note that the area demanded at the back of the solar panel for the Power Optimizer is 288 x 342 x 51 mm (WxLxH).

1-3. Take into account where the mounting material will support the solar panel and choose the ideal position for the Power Optimizer.

1-4. Remove any possible dirt of grease with alcohol or naphtha and a soft cloth from the back of the solar panel where the Power Optimizer will be attached.

1-5. Remove the red covers of double sided adhesive tape the at the back of the Power Optimizer.

1-6. Attach the Power Optimizer to the back of the solar panel.

 

 

2. How to connect the Power Optimizers on the rooftop to each other

In order to optimize the total PV installation the Power Optimizers behind every module are connected in parallel to each other. The result is a parallel network which boosts the total power generation of the PV installation. For this installation the 3 core DC cable 2,5 mm2 is used.

 

 

Back side first solar panel and no cables connected
 Back side first solar panel and MC4 cables junction box connected
End Cap first Power Optimizer thumb 2m DC Cable
End Cap and all cables connected on first Power Optimizer Connecting the first Power Optimizer to the next one
8m DC cable Close-up 8m DC cable

 

 

 

2-1. Start with the 1st module. This is the module that is most distant from the inverter.

2-2. Connect the MC4 cables of the 1st module's  junction box to the MC4 connection points of the Power Optimizer: connect the + with the + and, in turn, the - with the -.

2-3. Place the supplied End Cap on the female DC connection point, the 'OUT', of the 1st Power Optimizer. Once this is done, connecting the 1st Power Optimizer to the 2nd is easy and plug & play.

2-4. Use the 1st 3 core DC 2m cable 2,5 mm2 to connect the 1st Power Optimizer to the 2nd one.

2-5. The female DC connector of the 2m DC cable is plugged in the male DC connection point, the 'IN', of the 1st Power Optimizer.

2-6. Continue with the 2nd module and connect its junction box to the 2nd Power Optimizer. Now connect the 1st Power Optimizer to the 2nd Power Optimizer by plugging the male DC connector of the 1st 2m DC cable in the female DC connection point, the 'OUT', of the 2nd Power Optimizer. Module 1 and 2 are now connected in parallel to each other.

2-7. Repeat these steps for all Power Optimizers used in the PV system. For the module most nearby the inverter, the so-called last module, you will end with an open male DC connection point, the 'IN', of the last Power Optimizer. Plug the female DC connector of the custom length 3 core DC cable 2,5 mm2 in this 'IN' connection point of the last Power Optimizer.

2-8. The other cable end of this custom DC cable has no DC connector but is stripped. The 3 wires of the DC cable are clearly visible: red is the +, blue is the - and black is the integrated safety wire and is 0. These 3 symbols (+,-,0) are also displayed on the DC connectors, so connecting the 3 wires of the DC cable to a DC connector is straightforward. Pass this stripped cable end through an existing hole, or drill a hole of 9 mm for the 3 core 2,5 mm2 DC cable. The angle of the custom length DC cable entering the inside determines the exact diameter of the drillhole., to the inside of the house/building where the inverter will be mounted.

 

 

3. How to mount the Inverter 2400 inside

The inverter must be placed indoor.

 

Wall bracket for Inverter 2400
 Close-up 8m DC cable

 

3-1. Mount the wall bracket for the inverter horizontally inside the house/building to a flat surface using two screws. This wall bracket will carry the weight of the inverter (about 38 kg).

3-2. Mount the inverter by hanging it on the wall bracket. Use an extra screw at the bottom of the frame of the inverter to stabilize its position. 

3-3. The stripped custom length 3 core 2,5 mm2 DC cable is now ready to be assembled. 

 

 

4. How to connect the Power Optimizers to the inverter

Now the Power Optimizers are connected to each other also the connection from the modules on the rooftop in parallel to the inverter inside must be made in order to form the 400 Vdc network: the Femtofrid®.

 

Top view female DC connector Connect custom length DC cable to Inverter 2400

 

 

4-1. Assemble a female DC connector to the stripped DC cable end of the custom length 3 core DC cable 2,5 mm2 by connecting the red wire of the DC cable to the + , the blue wire to the -, and the black wire to the 0 of the female DC connector. 

4-2. Connect the assembled female DC connector of the custom length DC cable to the male DC connection point of the Inverter 2400. All the modules and the Power Optimizers are now connected in parallel to the inverter. The whole DC side has now been installed. You can now safely continue with the AC side of the installation.

 

 

5. How to install the AC side

The installation of the AC side of the inverter feeding the solar produced energy to the mains needs to be performed by authorized installers in accordance to the local requirements for low voltage installations applicable for the country in which the PV system is installed. For the Netherlands for example the local requirements are laid down in the NEN1010. The name plate of the Inverter 2400 displays the required information for installers in order to complete the installation on the AC side in line with these local requirements.

 

Connect AC side Inverter 2400 to the mains Top view female AC connector
Side view female AC connector Name plate Inverter 2400

 

 

After the installation has been completed at the DC and AC side the Femtogrid Solar System can now be powered up. Subsequently, the monitoring component can be installed.

 

6. How to install the Monitoring Box

The Monitoring Box is a communication device that sends the data logging of the PV installation to a personal website, the Monitoring Portal. The data logging contains information about the energy yield in kWh and is transmitted to the Monitoring Box by the inverter using a wireless ZigBee interface. All Power Optimizers and the Inverter 2400 are equipped with this ZigBee functionality. 

 

Monitoring Box Monitoring

 

6-1. Drill a hole of ø 5 mm width and 35 mm deep. Do not let the screw sink in completely, as the Monitoring Box will be hung up on the screw. For extra stability a second drillhole can be made 85 mm directly below the first drillhole. Open the left door of the Monitoring Box and use the hole on the right for the second screw. Mount the Monitoring Box vertically and close to the inverter. 

6-2. Next to the left door on the Monitoring Box there are three little pinholes. The two pin holes above each other are two LED's: one green LED and below it one orange LED. The pinhole next to them is the button to test the netwerk. Push the self-test button using a paper clip, and, while pushing, connect the mini USB 5V adapter. Keep pushing the button with the paper clip for 5 seconds.

6-3. Push the button one more time for 0.5-1.0 second to start up the ZigBee netwerk.

The total installation of the PV system has now been completed.

We will describe the installation procedure for the Femtogrid Solar System with one Inverter 2200. As a result, the DC Cable used is 3 core 2,5 mm2.

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