Thanks Everyone for the feedback. I am going to go ahead and reduce my projected yield by an additional 5% and increase the install cost to include a 2kva buck/boost xfmr as an option. If the economics hold up, I have confidence that we can go forward without the xfrm, but we will have it in the wings to address voltage faults if they occur. Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 <http://www.berkeleysolar.com/> www.berkeleysolar.com
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Mark Frye Sent: Monday, February 14, 2011 7:42 PM To: 'RE-wrenches' Subject: [RE-wrenches] Can I handle the voltage drop? Folks, I am working on a proposal. It's a ground mount 300+ feet from the meter. There is an existing, near by run of #2 copper I can tap into. The desired system is relatively large, 64 amps AC max. I have modeled the yield using PV watts hourly data, applying a power loss based on the voltage drop at the varying current. This model shows a 3% loss in annual yield with the #2 copper. Because of the economics of the system, we can absorb this loss. My concern however is that I do not want the inverters to shut down when operating at higher currents. I do not want a high AC line voltage fault due to the voltage drop on the line. At the 64 amps max, the drop would be about 4%. Of course all the manufactures I talk with recommend keeping the drop on the AC below 1.5%. I am looking at using Enphase inverters which spec an AC voltage range up to 264V, or 10% above 240V nominal. What experience have folks had out there? How far can one realistically push the 1.5% limit and still avoid AC voltage faults when there is high voltage drop on the line? My guess is that everything would work out fine, but I stand to loss a huge amount of energy if the inverters are spending all their time faulting and resetting during daily peaks. Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 <http://www.berkeleysolar.com> www.berkeleysolar.com
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