Single solarpanel setup

[Orchidius]

Hi there,

I'm looking into buying the solarpanel system to put on my brand new, shiny stern-arch and like a good boy I've been doing my homework. Between the fact that it's not a conventional home-setup, the very small size of the setup and the furious arguments between the solar companies and people that seem to know it much better (handybob just to name one), I'm afraid I've gotten more then a little confused. What seemed like the best idea to begin with is considered dangerous by some, inefficient by others and I just don't know what to think anymore...

So, I was wondering what your opinion is on the different components and their correlation. Maybe I won't have to buy all new gear then, once it becomes clear I should've consulted with the CF before going with my original idea .

Panel

I don't have room for two panels on the arch, so I want to go with the biggest possible on top of the arch. This seems to be around the 250W marker. Should it truly be necessary, I can always add more to the side, but I'm pretty sure that won't be the case. On the second-hand market there are plenty "new" panels for sale leftover from a job. These are mostly home-setup panels though, and I've read that regular charge-controllers can't deal with the higher voltage. Is this correct? MPPT controllers can handle it I've also read, true or false?

Controller

An MPPT controller seems the most logical choice as far as efficiency is concerned. However, Handybob seems to believe (among others, including the people at bogartengineering) that for small setups, mppt makes no sense. What's your take?

Also, I was planning on buying a charge controller from ebay as there are plenty of affordable ones on there to keep cost down and it's such a small system anyway. What do I stand to lose here? Is the charge controller something prone to breakage? Is much of the efficiency tied up in it?

Cables

Some sources mention that with an mppt controller, you can run smaller gauge wire down from the panel. Others claim this is ********... What wire gauge would you run from the panel to the controller (250W, about 9ft) and from the controller to the batteries (inches)?

Thanks!

[Orchidius]

Bumpp

[Sailmonkey]

What is the panel voltage and your house batt voltage?

If it were me, I'd grab a 250 watt panel rated at 36 ish volts and feed that into a smaller mppt charge controller. Avoid eBay controllers at all costs unless of a known pedigree. Also be sure to check the specs of the controller to be sure input/output voltages are within design range.

[djmarchand]

A 250 watt panel is probably rated for about 35-40V open circuit and at about 30 V at its maximum power point. So to charge 12V batteries you absolutely need an MPPT controller to convert the 30 V panel output to the 13-14V it takes to charge your batteries.

I don't believe in no name Chinese controllers. Buy one made by Morningstar, Blue Sky, Outback, etc. It needs to be rated to handle the input voltage- roughly 40V max and the current to the batteries- roughly 20 amps. Blue Sky makes a Solar Boost 3024i that meets these specs and costs about $250.

To handle the panel's current- about 8 amps with minimal voltage drop, you will need to wire it to the controller with 14 gauge wire. Wire the controller output to the battery with 10 gauge wire.

David

[bgallinger]

djmarchand has the facts right. Just add Gensun to the suggested list of MPPT controllers

Bruce

[Yeti]

Here's my setup as an example for you. Its pretty much right along the lines of what you seem to be doing.

I have a 230 or 235 watt panel on my boat. It does something like just under 30v at just under 8 amps. It's a more or less no name panel from china that I got off of craigslist for $300. Its mounted flat on top of the bimini just behid the boom.

The charge controller is a Sunsaver MPPT 15 amp. Bought online for $200. This contoller is only rated for 200 watts but as the panel is flat mounted in San Diego it will basically NEVER put out its full potential as its basically never directly facing the sun. I called the tech suppourt people at Morningstar about the combination and they said it should be no problem.

The set up has been on my boat for about 2 years now and its been basically trouble free. It keeps 4 golf cart 6v batteries and a group 32 topped and ready to go at all times as well as an Alder Barbour Cold Machine running 24/7. My boat is on a mooring and I am basically never on shore power.

[neptunesjester]

My Midnite Solar Mppt controllers work great

[konakoma]

Originally Posted by Yeti

Here's my setup as an example for you. Its pretty much right along the lines of what you seem to be doing.

I have a 230 or 235 watt panel on my boat. It does something like just under 30v at just under 8 amps. It's a more or less no name panel from china that I got off of craigslist for $300. Its mounted flat on top of the bimini just behid the boom.

The charge controller is a Sunsaver MPPT 15 amp. Bought online for $200. This contoller is only rated for 200 watts but as the panel is flat mounted in San Diego it will basically NEVER put out its full potential as its basically never directly facing the sun. I called the tech suppourt people at Morningstar about the combination and they said it should be no problem.

The set up has been on my boat for about 2 years now and its been basically trouble free. It keeps 4 golf cart 6v batteries and a group 32 topped and ready to go at all times as well as an Alder Barbour Cold Machine running 24/7. My boat is on a mooring and I am basically never on shore power.

Hey Yeti Am installing Kyocera 250W panel on davits, 14 AWG to BlueSky 2512IX MPPT Controller. Have same setup (4-6V deep cycle flooded batteries), divided into 2 house banks, and 2-12V cranking batteries wired in parallel. Primary MPPT output will go to house batteries and auxiliary to cranking. My question is, what wiring schematic did you use from controller to your house bank and Group 32, and with or without diodes? Nothing like hearing from someone with experience with the same installation.

[sailorboy1]

Well I installed a larger 290W higher voltage panel and used a fancy MPPT controller. The larger panel was less expensive per watt than a smaller panel and I also saved on mounting stuff and wiring by using a bigger panel instead of 2 smaller ones. When I did the total project cost estimate the bigger panel was less expensive than the multiple smaller ones even adding in a higher cost controller (that also had more features) to reduce the voltage from 32V to 12.5-14.4V.

[JK n Smitty]

Here is a link to a right up by Maine Sail that might be helpful.

Good luck and fair winds,

Jesse

[Yeti]

Originally Posted by konakoma

Hey Yeti Am installing Kyocera 250W panel on davits, 14 AWG to BlueSky 2512IX MPPT Controller. Have same setup (4-6V deep cycle flooded batteries), divided into 2 house banks, and 2-12V cranking batteries wired in parallel. Primary MPPT output will go to house batteries and auxiliary to cranking. My question is, what wiring schematic did you use from controller to your house bank and Group 32, and with or without diodes? Nothing like hearing from someone with experience with the same installation.

My setup has the 4 6v golf cart batteries as the main bank and one group 32 as the reserve/emergency bank. Each bank has it's own bus bar that all connections are routed to. The charging loads of the alternator and solar system are routed to the main bank bus bar. The shore power charger has leads to both bus bars. Between these two bus bars is an automatic charging relay. I have not placed any diodes in the system as the charge controller has them built in. There is a third bus bar that is the common ground for the boat. Wire sizes used in the solar system were whatever was suggested in the manual of the charge controller.




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