I just brought online 36 panels on a steeply sloped TwoFaced Rail. 18 east facing and 18 west facing. The old PV on that meter is about 8 years old and consists of 41 panels. Enphase monitoring tells me only 40 of those are currently working. The addition may push my production as high as 19kw. That could overload my 15kva transformer and cause energy loss. My hope is that east and west facing will not much increase my peak power. I plan to add a second parallel TwoFaced Rail with another 36 panels. I'm pretty sure that WILL overload my transformer.
https://photos.app.goo.gl/xmrSwsfX5coUGir49
Older photos from previous post:
https://photos.app.goo.gl/zHSQb55p67wGeCtQ6
The new TwoFaced Rail is now my favorite configuration. I expect them to minimize peak power which has been causing me so much trouble with my small transformers. The rail better securely supports the panels. The negative is that the backs of the panels are nearly inaccessibly so operation can not be easily monitored; that is a big positive on the old one faced rails. I expect that propping up one middle panel will allow me to look at a total of six panels. Something I have yet to try.
7/22/19
Well, I've had occasion to test my maintenance access:
https://photos.app.goo.gl/dEcpFX5yXXrnwrqX6
A panel is propped up with a 5' long board. It does give me good access to 6 panels, inverters, and wiring.
The reason? I got a batch of bad inverters and am having to change them out.
The first rail is performing very well by minimizing mid day peak power and supplying good early and late power.
I now have a second rail installed. Shown in the above photo. Since I observed on the first rail that two joints of pipe will support 38 panels, I will have 38 on the second rail and 36 on the first. The second rail is not yet fully populated due to lack of stock of panels, inverters, and weed block metal roofing.
I'm "pretty sure" a full second rail will max out my transformer capacity like my other two transformers. I'm also "pretty sure" my total energy production on all meters would be quite a bit greater if ALL my panels were east and west facing. I started my PV adventure by installing south facing panels at all three meters. Live and learn.
7/16/19 Stopping Point
I finished populating the 2nd TwoFaced Rail across the road. I was surprised to see no evidence of high voltage shutdowns. We will see what the BlueBonnet report, available tomorrow says; I've had all 36+38 new panels producing since just after sun up. Before the new project, my over production has been about 40kwh/day. Before the 2nd rail was completely producing, it had risen to near 90kwh/day. I predict today's over production will be about 95kwh.
About 2:30pm, after "solar noon" I believe, I measured 14+ amps at 240vac on each of the rails. Individual panel DC currents were 1-2 amps for east facing and 5+ amps for west facing. The total of about 28 amps going into 6 gauge wire on a 50 amp breaker indicates that I have wiring capacity to add a 3rd rail in that area. Transformer capacity is likely another story.
I'm pleased to see that my loop of drop cable strategy seems to work ok. Up to 38 panels feed into a loop of drop cable. Each end of the loop is tied to a 10 gauge that connects to a 20 amp breaker. The 14 amps is a bit too much for the 12 gauge drop cable wire size but, being a loop, it doesn't all go through a single section of the wire.
My next project is not imminent but will likely be reconfiguring some of the south field panels into a TwoFaced Rail.
8/1/19
Up to date costs for these 74 panels:
1) Six joints of $15 pipe, used oil field salvage. $.61/panel
2) Sixty panels delivered to Austin, $3202. $53.37/panel
3) 48 Enphase M215 inverters delivered to Dale, $1566. $32.63/panel
4) 240 drop Enphase cable delivered to Austin, $3350. $13.96/panel
Total for principal components: $100.57
Aside from labor and hauling from Austin, incidentals are
1) About 100-150' of 6 gauge romex plus the about the same length of conduit
2) 1 50 amp breaker, 2 20 amp breakers.
3) A $10-$20 breaker panel.
4) About 30' of 10 gauge romex plus about the same length of conduit.
5) Various wire to hold things together, maybe 100-200'.
6) A few wire nuts.
Total above estimated to be about $500. About $6/panel.
This is marginally below my previous estimate of $110/panel; that estimate did not include the "incidentals". $.45 per rated watt.
Total cost for the 74 panels was about $8140. Rated capacity is 18kw. Observed production has been about 7kw. That production should persist for about 8 hours per day in clear weather. So, hoped for production could reach about 60 kwh/day. Production estimated from Bluebonnet meter reading reports average about 40 kwh/day. Hoped for value of production, at $.06/kwh, maybe $2.40/day. 3392 days for pay back. I'll just hope for 50 kwh/day. The good weather (60kwh/day) payback would be 2261 days. Time MAY tell.
Everything started working when you replaced the inverters? Do you use the Android Enlighten App? It shows a graph of this years power vs last month's power and last years power. It would be interesting to see how the shape of the power curve has changed with the addition of the East-West panels.
ReplyDeleteI've failed to keep track of inverter locations and serial numbers. Bluebonnet gives me a good clue that I have flattened things out some. My "within 50% of peak hours" have been about nine since the first TwoFaced went in. Before, it was 7-8.
ReplyDeleteIn addition, I don't think the Envoy has picked up the new inverters yet. May never since old inverters are within about 50' of the Envoy and new inverters have to go all the way to main panel and back. An estimated 300 feet.
The Envoy at the pool has been good about seeing inverters, though. That Envoy no longer has internet access. I haven't yet tried to figure out why.