Growatt 5000MTL test
The original test report for the Growatt 5000MTL was published in PHOTON International this summer (see PI 7/2012, p. 98). Aft er a few initial problems due to a defect, this transformerless, single-phase device with a nominal DC capacity of 5.2 kW delivered a perfectly acceptable performance. Its PHOTON effi ciency of 96.2 percent for medium irradiation translated into a »B«, and when weighted for high irradiation, its 96.8 percent was enough to earn it an »A.« However, even before the test report appeared (the test itself was carried out at the start of the year), Growatt implemented a substantial improvement. Th e 5000MTL has been equipped with new fi rmware since February 2012. According to the manufacturer, the hardware has not been modifi ed, and PHOTON Lab was also unable to identify any changes. A device with the new operating soft ware, S.2.1, underwent testing again (another soft ware for the display, S.1.8, remained unchanged), and this time a double »A« emerged: 96.8 percent for medium irradiation and 97.1 percent for high irradiation.
A multi-tracker device like the 5000MTL can be run in several diff erent operating modes: with the MPP trackers under symmetric or asymmetric load, or with the trackers connected in parallel. Th e inverter is, however, only graded according to symmetric load. The most important factor in its improvement is that the development of the conversion effi ciency is signifi cantly more harmonious under the new fi rmware, and above all the interplay of the two Growatt has considerably improved its two-tracker device, the 5000MTL, by deploying new fi rmware. Romana Brentgens / photon-pictures.com trackers has improved. Th e MPPT adjustment effi ciency is, apart from a few barely perceptible exceptions, consistently above 99 percent. A slight improvement can also be observed under asymmetric load. Th e older fi rmware did not give any cause for criticism when the trackers were connected in parallel. Th ere is also one small change to the MPP voltage range specifi ed by the manufacturer, which now spans 250 to 540 V instead of 250 to 550 V. Th e distance to the maximum DC voltage of 600 V is therefore still far too small, and, even with crystalline modules, only the MPP voltage range of up to around 475 V can be utilized without limitations.