Installing a module optimized solution such as SolarEdge can be a little confusing for the first time, when all your previous experience has been with traditional string inverters. It can also be a liberating experience for PV installers. With a SolarEdge installation a lot of the traditional design steps can be completely eliminated, giving an installer unparalleled flexibility when completing an installation. The SolarEdge system has features that many installers new to the technology are not yet fully aware of, so to help fill in the gaps this is a rough guide to the differences you’ll encounter when installing your first SolarEdge PV system.
We strongly recommend that you should always connect your system to the internet. This is not an essential step for the system to work and your customer will still get all the benefits of shade resistance from the system, however if internet access is available, get it connected. Being online gives you and your customer access to the free SolarEdge monitoring portal, allowing you to monitor the complete system right down to module level. If something is not working as it should, SolarEdge will also be able to troubleshoot the system remotely, vital support, especially for your first few installs. The connection is made using a standard Ethernet cable from the inverter to the householder’s router or connection can be made wirelessly using the Zigbee option. Many installers also use Netgear Ethernet for connection over power line plugs; although this system usually works perfectly well, bear in mind it is not the SolarEdge supported solution.
Choosing the correct optimizer
Most standard 60-cell 250Wp solar PV modules work with theSolarEdge OP250 250W Grid Optimizer. However, higher power modules like the forthcoming LG NeoN or thin film modules such as the Solar Frontier need a different optimizer. Installers can mix and match different optimizers on a system, even on the same string, meaning for example you can have a string of 2 x Hyundai 250s, 2 x LG NeoN 300s, 2 x Solar Frontier 155s, 2 x Kyocera 190s and 2 x UpSolar 245s – ideal for putting together a test rig in your offices.
No maximum string voltage
You don’t need to worry about maximum string voltage and traditional string design. Regardless of the modules panel being used, you always have the same condition. For single phase systems, you must have a minimum of 8 and a maximum of 25 optimizers per string, or a maximum current of 15A per string. For three phase systems you need a minimum of 15 and a maximum of 50 optimizers per string, or again a maximum of 15A per string. You do not need to put modules on different roofs onto different strings, for instance you can have a 16 module system with 6 panels on the east roof, 5 on the south and 5 on the west roof, all on the same string. Be wary of making the mistake (for example on a 14 panel east-west system) of putting 7 modules on each string as this will bring you below the minimum of 8 required.
It is preferable for all 14 panels to be on the same string. For a 16 panel east-west you have the choice, depending on what is more convenient.
Six optimizers must be working for the system to work. Therefore, a design should mean that you should always have at least 6 modules in sufficient sunlight that they are generating something, so in an 8 module system for example, no more than 2 modules can be completely shaded.
Communication between the optimizers and inverters is over DC power line. Therefore there is no need to install any extra communication cables meaning there is no risk of wireless interference.
Positioning the optimizers
Mount all the optimizers in position on the mounting rail before placing and connecting the PV modules. The optimizers can be connected to our standard Alpha rail using a standard Rail to Roof Hook Connection Kit as though it were a module clamp together with an additional washer. Once configured, note the position of the optimizers on the layout. The optimizers have stickers which you can peel off and stick to a layout sheet. There is also an iPhone app available which can scan the bar-codes and record the position. Download the SolarEdge App here. The layout can then be sent to SolarEdge, who upload it onto their monitoring portal allowing you to view see the modules of your system in their correct positions.
Test the string voltage before connecting the inverter
When the optimizers are not connected to the inverter they produce a ‘safe’ 1 V voltage for fire safety allowing you to calculate tell how many optimizers are working. For instance if you have 12 in a string and there is sunlight, then you should measure 12 V on the string. If this is not the case, then there may be a connection error. A bad optimizer does not stop the system from working. The most common fault on a SolarEdge install is a bad connection made between the module and the optimizer. This optimizer will not work but all the other optimizers will continue working, so double check the string voltage matches your number of optimizers.
Complete Inverter/Optimizer pairing in daylight
The pairing will not take place properly in the dark. If for some reason the install has been late, pairing can be done remotely, as long as you have connected the inverter to the internet.
Use a 3G router
If any of your installs do not have internet connection, then buy a 3G router for times when you have to troubleshoot those sites. There are now 3G routers such as Zoom that can connect to the internet through your smartphone, a cost effective way to allow SolarEdge remote access to any problem sites you might have.
The DulasMHH technical team is available to help you with any design questions or on-site issues you might have, call them on +44 (0)1654 700777. We also have direct access to the SolarEdge global technical support line, as well as technical support staff in the UK.