Best solar panels for the buck

[prroots]

Originally Posted by bljones

heater hose.

Thanks, interesting! Wonder if it comes with 5/8-3/4" ID?
Pete

[mdbee]

I was wondering a couple of things. I spoke to a couple of "marine" wire suppliers. They weren't much help in identifying a "UV resistant" wire. One did say to use black, since it was more resistant because of the color. (most "marine" duplex wire seem to be white. I remember on one of your posts, you gave some "alphabet" codes to look for but most of the on-line sites don't seem to list all of the specs. What / where do you suggest looking? Looking for 12g duplex.

Another issue on solar panels. On a smaller 20w - 40w panel, what type of connector do you recommend to connect the panel to the boat's system? I want to be able to remove the panel when needed. A few years ago, I used a "2-wire trailer connector" type from an old, dead flexible charger. It works great, with no corrosion issues but wondered what are other options.

Thanks!

[aeventyr60]

I used the Anchor brand duplex in White, it mostly runs under the panel, but has been outside for 14 years with no apparent degradation. On another wire run from the radar arch, where the wire is exposed, I used a flexible plastic cover to help in the fight against UV. This material lasted about 5 years, I just re wrapped the wire this week, it was getting brittle and starting to break. This all in the topics.

A ring terminal will work well, heat shrinked of course. I have a single run from the panel to the solar controller. No breaks in the wire.

[prroots]

Originally Posted by aeventyr60

I used the Anchor brand duplex in White, it mostly runs under the panel, but has been outside for 14 years with no apparent degradation. On another wire run from the radar arch, where the wire is exposed, I used a flexible plastic cover to help in the fight against UV. This material lasted about 5 years, I just re wrapped the wire this week, it was getting brittle and starting to break. This all in the topics.

A ring terminal will work well, heat shrinked of course. I have a single run from the panel to the solar controller. No breaks in the wire.

Thanks. I just picked up a very thin wall, white plastic bilge pump hose with the ideal ID for my 8AWG/duplex wire (flat 5/8"wide). It's white and very flexible. I'll be happy if it also lasts for 5 years
Pete

[prroots]

After redoing my wiring to make it easy to switch back and forth between parallel and series we finally have a clear sky for awhile. Here is a graph showing the power in both conditions. The lowest curve is array voltage which shows whether we're in series or parallel mode. One anomaly is that input power is lower than output power while in parallel mode; I'm guessing that this must be due to errors in the shunt resistors. We see that the spread between input and output power increases while in series mode which verifies that controller efficiency decreases with higher Voltage. Of course, we also have greater line loss while in parallel mode. Since the output power is what matters, we see hardly any difference between the two configurations. Note: there was no shading at the time on either panel.

Since the output power seems to be unchanged in either mode, the conclusion I draw is that the loss of controller efficiency at higher voltages associated with series mode is almost exactly offset by the increased line loss in parallel mode. Our controller is providing all the results you see The boat is oriented so there is no shading on either panel. Once I complete these tests I will be investigating the effects on shading. That could get interesting; stay tuned
Pete

[aeventyr60]

How are you getting that data? I suppose your controller has a usb connection with some kind of data gathering device and or program on your computer?

[prroots]

Originally Posted by aeventyr60

How are you getting that data? I suppose your controller has a usb connection with some kind of data gathering device and or program on your computer?

Our Morningside TriStar MPPT 45 includes a built-in data acquisition system with 31 different variables that may be captured in real-time; pretty amazing: A free PC program is available to capture, record, and graph any variable(s) of interest. It's based upon an RS-232 interface.
Pete

[prroots]

Originally Posted by prroots

Our Morningside TriStar MPPT 45 includes a built-in data acquisition system with 31 different variables that may be captured in real-time; pretty amazing: A free PC program is available to capture, record, and graph any variable(s) of interest. It's based upon an RS-232 interface.
Pete

For those interested here are the 31 variables that may be collected:
Pete

[prroots]

I think I've come up with a test method that might allow me to more accurately compare series and parallel modes of operation. At intervals of approximately 30 minutes I switch back and forth between parallel and series. On these occasions, I record the collected Ah (one of the variables output by my controller) and time of reading. I then calculate average Amps during the interval by dividing the Ah accumulated over the interval by time in hours. This method will smooth out the erratic changes in output caused by cloud cover. Hopefully, the effects of cloud coverage and effect of boat orientation on shading will average out between series and parallel over the course of a day to make the comparison meaningful. I have attached a spreadsheet showing the results for an afternoon with heavy shading. The results are calculated in two different ways, but it does show that parallel outperforms series by at least 40% under the conditions encountered.

As an aside, I've discovered that when the wind comes from the prevailing direction just South of East, I get significant shading most of the day on the port side panel from the wind generator and its mast. What makes it particularly nasty is that the shading cuts across all 3 substrings. Despite that, I do not believe that any substring is being bypassed. I base that opinion on the fact that the array Voltage is 50-55 Volts while in series mode (see the attached graph). This suggests that both panels are contributing to the output. I wonder if the loss in solar power is compensated by the output from wind generator? I think not, however, the wind generator does create output on occasions when there is no solar to speak of. Knowing what I know now, I'm not sure if I would have installed the wind generator?
Pete

[Boatsmith]

Sun Electronics has very good prices on panels