What makes PV, power electronics and solar batteries more efficient and more intelligent? Lior Handelsman of SolarEdge analyses the trends
Innovation drives the PV markets worldwide, innovation is your prime business. Which trends do you see in solar power technology, especially concerning energy storage?
Lior Handelsman: First of all I think that there is a lot of technical innovation needed to get in streamline with other energy sources. Storage systems for solar power have a central meaning. Everybody drives lithium technology but I am not sure whether this will be the final decision. If you want to be successful in a commercial way don’t bet on a certain technology. But of course in the lithium batteries there is a lot of potential. As we have seen last summer when Tesla announced the new Powerwall battery. The real news was the price.
SolarEdge is system partner of Tesla. How close is this cooperation for new solar batteries?
We are not exclusively bound with Tesla. Non-exclusive relations are better. We will open our StorEdge system for other battery suppliers. But this will take some time, maybe it will happen next year or two.
Your business are the module level yield optimizers. How many of those power optimizers has SolarEdge already sold until today?
In Q3 2015 we crossed the frontier of eight million optimizers. Every three month we produce another 1.5 million.
And how many inverters do you make per year?
Per day around 2.400 inverters leave the factories of our contract suppliers. In the first nine months of 2015 we shipped 196.000 inverters.
Which are the most important markets for SolarEdge?
Our main market is the U.S.. But we are strong in Europe and Australia, too. Generally speaking, in Europe we are growing despite the shrinking PV market. But I hope that the European PV market will recover soon and grow again. We are expanding our team there. Take UK for example. All of our customers in UK are now reacting to the cut of the feed-in tariffs, with self-consumption and storage systems. All the knowledge that was developed in Germany is now pouring into the UK market. And also partially into Italy and France. Other interesting markets in Europe are the Netherlands, Denmark, Poland and Sweden.
Why don’t you build micro inverters? Wouldn’t it be logic to make this step and integrate AC-conversion into the module level optimizers?
It seems to be logical only at first glance. AC-conversion and grid connection are the expensive parts of the inverter. The system costs would rise dramatically if you make this for every single module including high voltage components for 400 volts, magnetics and cooling. It is better and less expensive to leave the AC-technology in the inverter and only operate the power optimizers on module level. You can easily operate the MPP tracking on module level, also the safety functions in case of fire and the monitoring. If the power optimizers are not connected to the inverters they only provide one volt. So it is very easy to find out how many modules are in the string for the inverter. 24 Modules mean 24 volts (DC).
So you go ahead with a shared system of DC power optimizers and specialized inverters?
Of course, we do. Because for our customers it all comes down to Levelized Cost of Energy (LCOE), first of all in commercial and industrial installations. Our power optimizers have an efficiency of 99 per cent. Only one per cent will be transformed into heat. With micro inverters you can reach 96.5 per cent efficiency. The heat load will be 3.5 times higher. Most modules are mounted on rooftops. It is almost impossible to reduce the heat, because the modules themselves run hot. It is easier to cool the inverter which is installed in a shady place.
You mentioned the LCOE, the costs for each kilowatt hour of solar power. How are the costs influenced by the system configuration?
Our power optimizers convert the module voltage into a standard DC-voltage level. The MPP tracking is an integrated function. That means that you can plan and install the module strings very easily. Up to 50 modules can form a string, much more than in traditional systems with modules and string inverters. You are independent from mismatch trouble and length of the strings. A standard inverter can just operate 22 or 23 modules. We can connect 50 modules in one string. We work with 1.000 volt technology but get the yield like a 1.500 volt system. The demand for DC cables with a SolarEdge inverter is much less than for a traditional string inverter system. Copper cables are not cheap. The bigger the installation is, the more decisive the cabling is for LCOE. We reduce the DC cable demand by almost half.
What is coming next out of your labs?
Our new fourth generation power optimizer will contain just one ASIC-Chip. The circuit board is very small, there are no active parts any more. This will be a great step in our road map for technology. The recently announced HD-Wave inverters will reduce the system costs furthermore. The low voltage Mosfets have much less switching losses than the IGBT. Normally the IGBT switch with 16 to 20 kilohertz, the Mosfets with some hundred. Therefore the sine wave is almost ideal. We can use smaller magnetics to clear the sine wave for the grid, the power density of the inverter increases. We can build the devices much smaller. A HD-Wave technology inverter for six kilowatt has a weight of only 9.5 Kilogram. For us it is a clear strategy: We win the markets with innovation and value technology. We can’t stop it. Then we have no stand against price pressure in the industry. (HS)
Did you enjoy reading the interview “What makes PV, power electronics and solar batteries more efficient and more intelligent? Lior Handelsman of SolarEdge analyses the trends”? Also, discover, what Dr Matthias Vetter of Fraunhofer ISE or Santiago Senn, director of LG Chem Europe on pv Europe had to say about innovation in storage systems, markets and distribution and which opportunities Andreas Piepenbrink, the CEO at E3/DC sees for the energy storage market.