Thursday, February 14, 2019

Day 37 - Modest Solar Expansion

I guess Needles was the place to be. At least when this screen capture was done. Actually, it has been raining on and off since late last night. Enough for there to be puddles in the sand of the campsite. I think that Bridget may have here hands full dragging a couple of unwilling dogs around the campground. The National Weather Service has been putting out a flash flood warnings for the area.

I’ve made plans to return home for several days next month. This is to meet the State of Alaska retirement system requirement to not be out of state for more than either 89 or 90 days. I’m not sure which it is. Plus, I needed to get taxes done and a few other things. By late afternoon, the steady, light rain had ended but it was still kind of dreary.The cooler daytime temperatures meant the furnace ran more and not much solar. Though, surprisingly, we were still getting 5 amps around noon.

I’ve been looking at a solar web site called Continuous Resources, LLC, that was one of the exhibitors at the Quartzsite RV show. At the time, I was looking only at Renogy 100 watt panels to match the ones that we already have installed on the RV. But, it really doesn’t matter as long as the panel is 12 volts. This is their 180 watt, nominally 12-volt panels with an Isc of 9.87 amps and a voltage of Vmpp of 18.95 volts. The price for these panels is about $20 more than the 100-watt Renogy panels which have an Isc of 5.75 amps. That seems like a good deal to me. BTW, this is where they get their 180-watt rating. 9.87 x 18.95 = 187 watts. For our system, 14.8 x 9.87 = 146 watts. Still a good deal.

Their mounting brackets are a bit more expensive than the Renogy brackets but they do tilt. The tilting feature is important as I plan to install this panel on the passenger side of the roof and it will be over the combiner box. With the ability to tilt the panel, I will still have access to the box. At least, I'm pretty sure that the panel will fit in that spot. I'll go up on the roof and take some measurements when it's not raining. I've ordered one panel and associated installation pieces. With this addition, our maximum charge current will be around 33 amps. I'm thinking that this will allow us to run the refrigerator off of the inverter while traveling, especially on sunny days.  

6 comments:

  1. Hi Richard,
    Interested in your comments about the requirement not to be out of state for more than 90 days. Does this adversely affect your superannuation payout? There's a similar scheme in NZ.

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    1. Both Bridget and I retired from the state of AK and if you maintain residency and not be out of the state for 90 days at a time, they bump your pension by 10% to account for the higher cost of living in Alaska.

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  2. Are PV panels wired in series, been a while since I thinking about that but memory says if one panel is shaded in a series wiring plan the other's output is diminished. How are you dealing with that?

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    1. They could be. If you had either a higher voltage system or use an MPPT charge controller, the panels could be wired in series. And if they are wired in series, a shadow on one panel will pretty knock out most of the output from all of the panels in that string. When they are parallel, only the output of the partially shaded panel suffers. I remember reading that even 10% shading will pretty much kill the output from a panel. I don’t know if the addition of blocking diodes within the panel partially addresses that or not.

      All of my panels are wired in parallel. Currently two 100 watt panels to each 10 AWG cable pair into the combiner box on the roof. When the new panel is installed, I am planning on 3x100 watt on one cable pair and the new 180 and the other 100 watt panel on the second pair. I don’t have the tools to add another weather-tight cable entry into the combiner box so this is an easy, short-term solution.

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  3. Sounds like you are doing a great job planning to meet Alaska's time requirements, and using it to complete taxes is a bonus! Preparing to do taxes shortly too...fun, fun! L

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    1. I hate doing taxes. That may be today’s task while dry camping behind the museum.

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