<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>Hi Jay-</div><div>Here is a somewhat dated Engineering Bulletin from Solar World with nice diagrams. <br></div><div><br></div><div>Mark- </div><div>NEC requires transformerless inverters to be handled differently than the ones with transformers.</div><div>Neither DC+ or DC- is grounded, so there no ground fault fuse inside the inverter.<br></div><div>Both DC+ and DC- are fused external to the inverter. </div><div>Both DC+ and DC- are switched by the DC Disconnect.<br></div><div>PV wire is required to better ensure against ground faults since they become so catastrophic.<br></div><div><br></div><div>Don Barch</div><div>Energy Solar</div><div><br>Jay <<a href="mailto:jay.peltz@gmail.com">jay.peltz@gmail.com</a>> wrote:<br>
><br>
</div><div>>Hi Dan<br>
><br>
>Can you provide any documentation on this? <br>
><br>
>Thanks Jay<br>
>Peltz power. </div><div><br></div><div> >"Mark Byington" <<a href="mailto:markb@cobaltpower.com">markb@cobaltpower.com</a>> wrote:<br>
><br>
>"Transformerless inverters need fuses on both DC positive and DC negative<br>
>legs to protect the inverter in case of ground fault."<br>
></div><div>><br>>I could be wrong, but my understanding is that TL inverters are no different<br>
>than transformer type inverters in terms of DC fusing requirements - no fuse<br>
>required for one or two strings in parallel; fuses required on + and - leads<br>
>for 3 or more strings in parallel.<br>
><br>
><br>
>Mark Byington<br>
><br>
>Cobalt Power Systems, Inc</div></span></body></html>