The speed at which manufacturers are introducing changes from one product generation to the next is accelerating – currently, formats are scarcely available for more than a few months before another revised product is launched. But occasionally new module dimensions also bring new problems, be it in handling, plant design or logistics. Ever-shorter product cycles and hastily launched record-breaking modules with capacities of 500, 600 or even 700 W are not always welcomed with open arms, especially by those who have to work with them.
In recent weeks, module prices have stabilized at a high level across almost all technologies, but availability to fill short-term demand remains poor overall. At present, almost no modules are available on the market for below € 0.20/W, even for larger projects. New deliveries of significant quantities from Asia are expected in the April-to-June timeframe, but even those are likely to be in the high-efficiency sector and thus in the high-end price range. So far, none of the manufacturers have signaled that prices will come down significantly in the second half of the year – on the contrary. The high cost of raw materials continues to put pressure on module prices. Many prefer not to commit to any more binding prices to avoid another train wreck like at the beginning of this year when they could only honor their agreed contract prices by foregoing any profit. Delivery volumes to Europe were quickly capped as the focus shifted to more lucrative markets. Now, some players are waiting to see how domestic demand in China will shape up before writing delivery schedules and price lists.
In Europe, it will be interesting to see whether the current high demand for modules, driven primarily by the German market with up to 500 MW per month, will slow after the latest FIT deadline. The transition period runs until March 31, 2021, by which time rooftop systems of up to 750 kW must be operational to qualify for the full feed-in tariff. Demand from April onwards will largely depend on how quickly the players adapt to the new conditions and whether the small-scale sector in Germany, which is already booming, can compensate for the loss of installation volume in the medium-scale segment.
Over the past 12 months, PV panels have become increasingly larger and heavier thanks to larger wafer dimensions reaching the market. In my view, there is one main reason driving this: to make production more efficient, and thus less expensive. Especially in times of scarce resource and high raw material prices, this seems the only way for manufacturers to make a profit without their cell and module prices rising excessively. But for planners, installers and dealers, this creates new, sometimes intractable challenges.
A larger cell area also invariably entails a higher output amperage. Although the monocrystalline cells are first cut in half or even smaller, operating currents of 12, 13 or even 18 amps, as with Trina's latest Vertex module, are no longer a rarity. This confronts plant designers with the task of finding a way to connect strings that is compatible with the intended inverter, if this is possible at all. Often, new modules have such a high maximum current that two parallel strings can no longer be connected to a single input, which makes efficient utilization of the inverter difficult because the system voltage limits the length of the strings.
In addition to design difficulties, handling modules that exceed the 2m² limit is more difficult. Neither their size nor their weight allow single-person handling while adhering to occupational health and safety measures. Products for ground mounted applications, which recently have reached power ratings north of 550 W, leave mechanical handling as the only option. With glass areas of between 2.5 and 3 m² and weights exceeding 30 kg per module – even up to 40 kg for glass-glass modules. These products can only be safely installed with a suction lifter and robotic arm – provided there is no strong wind, mind you.
From a dealer's point of view, a topic that has also received far too little attention is packing density and pallet weight. Increasing the glass area invariably increases the unit weight, especially in the case of glass-glass modules. At the same time, however, the frames are thinner – in the worst case, at the expense of stability. Manufacturers want to save costs and pack more and more power into a box or container. But a pallet containing 31 modules at 32 kilograms, including all packing material, weighs in at more than 1,000 kilograms. Freight forwarders like to apply surcharges to such loads, which makes transport even more expensive. Usually these ton-heavy module crates are stacked two high in the truck or shipping container, and then have to be unloaded and moved to a temporary storage facility – or even worse, to a construction site. This is no longer possible with a pallet truck, hydraulic lift or other lighter equipment; heavy equipment must be available.
What is going to be the ideal solar panel format?
Rooftop modules should be optimized for handling even more so than products intended for ground-mounted systems to ensure trouble-free installation, ideally by a single person. A module area of 2m² should be the upper limit in any case, which is true with the current cell efficiencies for module types up to 400 W. If we move from the flat roof to the pitched roof segment, especially for small systems, aspects such as aesthetics and service life come into play. Black framed modules, or even glass-glass modules are a good choice. Since an individual weight of 25 kg should not be exceeded, the modules may have an output of up to 350 watts. For the smaller roofs on detached or terraced housing, even smaller panels in the classic 48 or 54-cell format – for example, measuring 1.5 x 1 meters at 300 W – are an attractive option. This is because, as module formats get larger, the limited clamping area of large-format panels makes it increasingly difficult to design a structurally sound substructure.
The ideal ground-mount module may well be somewhat larger. For ease of processing, however, 2.5m² and 30 kg should be the upper limit – a format of 2.3 x 1.1 meters and 550 W, for instance – at least for a mostly manual installation. On the shipping side, packing densities of 24 to 26 modules per pallet have a long and proven track record. The modules can also be transported upright – on a euro pallet or an industrial pallet, for instance. This enables efficient loading of containers, but the individual weight should be kept below 900 kg. An option to remove individual modules without the package collapsing rounds off my wish list.
I reached these recommendations on the basis of the above-mentioned installation and handling criteria, all of which seem important to me. In the hopes of stimulating a long overdue discussion on these issues, I explicitly welcome other opinions.
Overview of the price points by technology in March 2021 including the changes over the previous month (as of March 15, 2021):