Can I get the SOLERGY label for a solar thermal collector that doesn’t have an OG-100 certification?

No. OG-100 certification is required for the SOLERGY label in North America since the performance data from that program is used to determine the ratings on the label. The same is true for the SOLERGY label in the EU, where Solar Keymark certification is required. Technical performance ratings and certification are central to the SOLERGY label program.