Hello David, The minimum temperature rating for grid-tied inverters is dependent on the manufacturer's specifications. It's a choice they make as a part of the product design and certification.
The manufacturer must specify the coldest temperature as a part of their UL1741 certification effort, and that's the coldest to which it will be tested and verified as operational by the UL certification laboratory (NRTL). Will it operate below the min temperature spec? It might. But then again, it's not verified to do so. Some bad things can happen if the components don't handle cold very well, and power is applied (such as actual failure of parts.) Quality electrolytic capacitors are generally rated to -40C (which also happens to be -40F). Film caps are often rated for temperatures below -40C, but at -40C, other components such as microprocessor clock crystals and many integrated circuits will fail to operate, so the point of film caps being rated for colder temperatures than electrolytic caps is moot. Note this is "fail to operate", not "fail". Cold-temperature components rated to -55C *could* be used in inverter construction, but parts of this type add cost (sometimes considerably) to the finished product price. By the way .. to your point of cold temperature specs not appearing in writing ... Our PVAC Modules *are* rated to operate at -40C, and have been tested to that temperature by the UL test lab. This rating is stated in writing in our brochures as well as the PVAC Module Installation Manual/User's Guide. Dan --- On Sun, 1/15/12, Dave Palumbo <d...@independentpowerllc.com> wrote: > From: Dave Palumbo <d...@independentpowerllc.com> > Subject: Re: [RE-wrenches] Electrolytic Caps vs. Thin Film Caps > To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org> > Date: Sunday, January 15, 2012, 7:32 AM > Dan, > > Any worries with inverters located out in 30 below zero > temps with either Electrolytic Caps or Film Capacitors? > It's very cold here this AM (minus twenty something F) > and it makes me wonder about all the inverters, both > micro's and string, outside in cold weather areas. We've > been told in the past by SMA, Fronius and Solectria that > we should be good down to 40 below, although this is > typically not found in their technical documents in > print. > > David Palumbo > Independent Power LLC > 462 Solar Way Drive > Hyde Park, VT 05655 > www.independentpowerllc.com > NABCEP Certified PV Installer > Vermont Solar Partner > 24 Years Experience, (802) 888-7194 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
