Best Solar Panels for the Buck

[prroots]

We're seriously considering rearranging the orientation of the two 39" X 58" panels such that they are side-by-side with long dimension of panels oriented fore and aft. This would make the combination 78" in the athwartship direction and 58" in the fore and aft direction. The positives are 1) the panels are much less vulnerable when docking and 2) they are better supported in the athwartship direction by the inverted-U mount. The negative are 1) they are more prone to shading from bimini when tilted forward, 2) the tilt lock has to work against more weight (ie, overhang), and 3) they extend the length of the boat. The shading issue will probably force us to raise the panels a bit more. With this orientation, they only overhang the ends of the inverted-U mount by 5-1/2" vs 24-1/2" which seems more reasonable. Comments welcome.
Pete

[SunDevil]

It was posted here or someplace else, but there is a lot of good advice on the effects of shading panels on this website:
The RV Battery Charging Puzzle « HandyBob's Blog

[prroots]

We checked with the local metals outfit for the best type of aluminum to be used in the construction of the frame for solar panels. They recommended aluminum alloy 6463 bright dipped anodized. They said this is what the tuna towers are mostly built from. Has anyone experience with this or other aluminum alloys? With respect to angle it only comes in 2 X 2 X 1/4.
Pete

[endoftheroad]

Seahunter,

Sun Electrics put their name on that panel.
Is it Kyocera?

I have no solar on my boat, and am considering one of these panels.
For charging of ipads and small electronics.

The info on their website is very limited.
Are there sufficient mounting options for this panel?

Thanks

[SV Demeter]

I bought a pair of these and found their prices to be great and customer support excellent. Havent installed panels yet but but construction appears fine.

Solar Panel 100 Watt 12 Volt Polycrystalline Silicon PV

[prroots]

My Morningstar Tristar MPPT 45 controller arrived yesterday. I'm really impressed by its construction and features. It has a maximum PV (input) voltage rating of 150 Volts and maximum PV (input) current of 45 Amps so it's a bit overkill, but should provide great performance. It can handle system (battery) Voltages from 12 to 48. I watched a training video on it at:
http://www.morningstarcorp.com/en/su...cfm?ItemId=444
and it uses a very fast complete sweep of PV IV curve to set maximum power point; pretty sophisticated overall. Competitors do dynamic sweeping which just looks at a limited portion of the IV curve near the current setting. This can miss better power points when the IV curve has bumps in it. This is, of course, a bit of marketing; not sure to what degree it's significant.

My (two 200 Watt) panels have been delayed and won't arrive until Monday. This will give me a bit more time to fine tune the solar mounting. The support frame and tilt lock will be constructed from bright dipped anodized aluminum 6463 and the support structure from type 316 stainless steel.
Pete

[prroots]

Originally Posted by SV Demeter

I bought a pair of these and found their prices to be great and customer support excellent. Havent installed panels yet but but construction appears fine.

Solar Panel 100 Watt 12 Volt Polycrystalline Silicon PV

Thanks. I wish mine were that dimension, but then again I would need four to equal the wattage of my two. Everything on a boat is a compromise
Pete

[Jimbo485]

SunDevil above included a fantastic link to Handy Bob´s Solar Puzzle. It also really opened my eyes. As an engineer I thought I had my system worked out so I sat down and checked it all again using Bob´s advice.

And then promptly spent a full day re-wiring it and tweaking the charge controller.

The two major points I got out of his link was:
1) often our wiring is undersized because this is what the suppliers push on us
2) the bulk and float settings are often too low.

I had bought 630W of panels from Sun Elec in Florida in late 2010 and connected it up with the 340 W already onboard. They sold me 10AWG for 20´ runs between the panels and controller. The funny thing is that at West Marine the current and wire sizing table in the electrical aisle clearly shows that I should be using 4 and 6 AWG wires which I luckily bought at the time and had onboard. Unluckily I followed Sun Elec´s advice and used their 10 AWG wires in 2010.

Anyway I ripped it all out yesterday and replaced the 10AWG from Sun Elec with 6 and 4 AWG from West Marine. Immediate jump in results with over 50 A pumping into the batteries today at 11 am. While I was at it, I calculated that the 4 AWG was heavy enough to handle all the panels in parallel and so changed them all to parallel. The losses are insignificant.

With a total of 970 W of panels and 880 Ah of batteries, I can justify an MPPT controller and will consider it if we need more energy. For now we are fine with a Xantrex 3-stage charge controller. For anyone with less than 500 W, it seems cheaper to just buy another panel rather than an MPPT controller.

So the lesson is to check out what Handy Bob has to say and then recheck your own system.

Thank you to SunDevil for the link!

[prroots]

Originally Posted by Jimbo485

SunDevil above included a fantastic link to Handy Bob´s Solar Puzzle. It also really opened my eyes. As an engineer I thought I had my system worked out so I sat down and checked it all again using Bob´s advice.

And then promptly spent a full day re-wiring it and tweaking the charge controller.

Yes, it's a great link. Luckily I had seen it posted elsewhere (check out post #37 in this same thread by 70AMX) and took his advice to heart. My TriStar MPPT 45 manual recommends keeping the cable losses to < 2%. There are a variety of handy online cable loss calculators as follows:
Voltage Drop Calculator
Voltage Drop Calculator - for single and 3 phase ac systems and dc systems

I kept mine to <1%. Since I have an MPPT controller capable of 150 V input, I will be able to wire my two 200 watt panels in series with the following advantages:

• a. better cloudy day performance
• b. better early morning and late afternoon performance
• c. better performance when randomly shaded
• d. lower cable losses

However, the advantages of wiring in parallel are:

• a. About 1% greater controller conversion efficiency
• b. one panel will continue to output if other one shuts down due to shade on that panel alone

Morningstar tech support suggests that the series advantages outweigh the parallel advantages in the above case especially since one panel should not become shaded to the exclusion of the other.
Pete

[70AMX]

Originally Posted by SunDevil

It was posted here or someplace else, but there is a lot of good advice on the effects of shading panels on this website:
The RV Battery Charging Puzzle « HandyBob's Blog

The research that brought this link to the cruisers forum was mine, there is much solar information available in the RV community....many crossover things like refrigerators, stoves, fans ect are used by both communities and sometimes the RV directed product is cheaper and better made than the product made for the boating industry......and sometimes it will be vice versa.

[prroots]

As a mini-update, my two solar panels have arrived from SolarBlvd. It turns out they are a Photowatt model PW2050-210 panel rated at 210 watts apiece as shown here:
http://www.photowatt.com/documents/p.../PW2050_EN.pdf

Our fabricator is now constructing the aluminum frame. On Monday he is scheduled to weld the stainless steel support structure to our existing dinghy davits. In the meantime, I have completed the installation of our Morningstar TriStar MPPT 45 solar controller. I especially like the RS232 link back to laptop. It allows me to:

1. Monitor or log any combination of many many variables
2. Setup custom profiles
3. Update firmware as required

As a glitch, the PC monitoring software has difficulty connecting to the controller ie, it is intermittent. Morningstar tech support stated that this is not correct and they will send me a free replacement controller and return label for the existing one. Can't beat that for support
Pete

[capn_billl]

200 watts a panel isn't bad.

[prroots]

Can anyone recommend some type of flexible conduit to protect our AWG 8/2 (conductor) wire from the UV? The cable itself is flat and about 5/8" wide. Thanks
Pete

[familycruisers]

Liquitite is avalilable in 1/2, 3/4, 1 at any electric supply and has a multitude of fittings. They are all plastic, so no corrosion worries.

[Patrick_DeepPlaya]

Originally Posted by prroots

Can anyone recommend some type of flexible conduit to protect our AWG 8/2 (conductor) wire from the UV? The cable itself is flat and about 5/8" wide. Thanks
Pete

I am saying its the right thing to do, but my PO installed the solar panels in 1999 and the wires exposed to the elements are just in the standard white insulator. The boat has been in Mexico, the South Pacific, puget sound and now we're back in Mexico. Wire is holding up great.

Just some info for you...

-p