Solar cell material costs will always play a dominant role in manufacturers' budgets and strategies, but selecting the optimal array of equipment – whether for metallization or diffusion or module tabbing and stringing – should not be overlooked for its part in providing high throughput, lower costs and solid factory uptime.
What are the essential considerations for upgrading or replacing manufacturing equipment? First, the major solar equipment suppliers agree that overall machine efficiency and performance – and the resulting contribution to boosting throughput – will factor heavily into any decision.
These concerns, however, must be balanced with other, often individualized goals.
‘Throughput involves a cost calculation,’ says Rob de Jong, area sales manager at Tempress Systems. Customers must assess which types of equipment can best handle an increased speed or workload, because in many situations, increasing throughput will also multiply risks and liabilities if that piece of equipment encounters problems.
‘Targeting higher throughput on certain equipment is not always cost-effective, because prices of equipment rise, and the cost of ownership for the tool becomes a different story,’ de Jong cautions. Tempress' product offerings include a range of wafer-per-hour rates to accommodate individual needs.
Solar cell manufacturers will likely first wish to replace the equipment in their lines with the lowest yield or lowest throughput, says Patrick Hofer-Noser, CEO at 3S Industries.
Jan-Paul van Maaren, vice president of marketing at BTU International, adds that although criteria for line upgrades strongly depend on the individual manufacturer, the overall aim of the upgrade – increasing cell efficiency or lowering manufacturing cost per watt – will determine which areas of the process need to be changed.
In addition, machines that consume massive amounts of energy or consumables and can be replaced by energy-conserving models will make strong candidates for replacement, according to Ernst Epple, director of sales and service at Lotus Systems GmbH.
‘Costs for energy and supplies will increase,’ he notes, and replacement equipment makes sense, as long as it meets existing process requirements without requiring excessive maintenance.
Cost of ownership has become an increasingly important consideration during the pre-purchase analysis process, as well. The equipment vendors are quick to point out that a lower-priced option is often not the most suitable long-term choice.
‘Although costs of acquisition might be considered high, it is not so significant compared to the total cost of ownership of the complete business,’ says Xabier Herrarte, international sales manager at Mondragon Assembly. ‘Once a line is put into production, the cost of not being able to produce due to stoppage of the line – in addition to cell breakage – is much more significant than the acquisition cost.’
‘How many dollars you spend up front is fact; how much you get in return is promise,’ remarks Pete Kostic, director of sales and marketing at Komax Systems. He recommends considering the performance profile of a machine holistically – taking into account not only price, but also breakage rates, yields, spare-part availability and uptime.
Customers should also evaluate the post-sale accessibility and dependability of their prospective equipment suppliers. In particular, ‘Manufacturers should consider selecting suppliers with local support infrastructure to ensure rapid response times, process engineers to support tool installations, suppliers with a history of technical innovation and a strong financial position,’ says van Maaren.
The manufacturing steps at all points of solar cell and module production, of course, tend toward a higher degree of automation these days. But, in general, ‘The larger the company is, the more megawatts per square meter they will want to produce,’ Kostic notes. ‘That means they will want a more compact production line – fully automated and with traceability.’
‘When increasing production volume, it may make sense to automate manual processes to reduce the risk of operator failure,’ adds 3S' Hofer-Noser. The company provides customer assistance in calculating the return on investment at various automation levels for manufacturers considering a turnkey production line.
Similarly, Kostic says that Komax's tabber and stringer, while available with full automation, also feature a range of operator options that allow for different levels of human involvement.
For production equipment addressing certain process steps, however, this type of flexibility may be obsolete. Tempress Systems' de Jong reports that the company's tube-diffusion product, which features full cassette-to-cassette automation, requires only initial conveyor loading and late-stage wafer placement.
‘There are hardly any customers anymore who will buy this equipment without automation,’ he observes.