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Old 01-12-2015, 18:53   #1
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Taking Tumbleweed Off Grid..... Solar Advice

Hello Cruisers Forum! I've been reading this site for a couple years and finally signed up today.
So a little background: My girlfriend and I have been full time liveaboards in New England for the last 15 months on our Tartan 34, Tumbleweed. We are and will be in a slip w shore power through the 2015/2016 winter and going to a mooring ball in the spring of 2016.

So we have a few short, cold, dark months to get our solar up and running.

We dont think our power demands are that much...
Existing:
all interior lighting and nav lights replaced w LED
dometic 110/12v cooler/fridge
laptop for entertainment (We have a 19" flat screen tv mounted in the boat but figure that wont be used on the hook)
(2) 12v bilge pumps
(1) water pressure pump
(3) 12v usb sockets for charging phones, cameras, flashlights etc
fixed mount vhf

To be installed spring/summer 2016:
garmin 741xs chartplotter
garmin hd radar
garmin wind n water instruments
12 volt lewmar windlass

No autopilot, Monitor windvane

No macerator, head converted to C-Head composting toilet

Engine acts as water heater when needed or just heat water on propane stove so no power consumption there....

The plan on paper is 300 amp hour house bank with 300 watts of solar with 40 AMP MPPT charge controller. (AGM Batterys, not sure if were going 3 12v or 4 6v, we will do the 6v's series/parralel to 12v if they will fit)

Starting battery for Yanmar will be on its own 25 to 50 watt panel

just a thought, correct me if this is dumb: Windlass battery mounted forward (near windlass) with its own 25 to 50 watt panel. I thought it would be good to have a much shorter wire run (voltage drop) and given the windlass isnt used daily the panel should keep the battery topped off....

Just a couple of added notes: we are liveaboards now and plan to be cruising fulltime within 18 months. So for 2016 we really just need the solar array and battery banks to be able to run the dometic 50 quart fridge, interior lighting and charge phones, laptop and gadgets. we plan to have a 1500 watt inverter for the rare occasion we need to run 110v. (occasional bag o popcorn in the 700 watt microwave or charge power tools ect). We are not super concerned with the power consumption of the electronics as they will only really be used when underway (when nothing else but the refer will be running)

Are we way off course with a system of this size? Too Small

Any other ideas for being self sustained on a mooring ball not related to solar is more than welcomed as well!

The 18 month countdown to quitting the jobs, selling the cars and heading south starts now!
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Old 01-12-2015, 18:58   #2
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Your solar sounds like plenty to me. We've got a similar setup with 1/2 of your solar and it keeps up with our demands. We also have a 200 watt wind gen that only occasionally pulls it's weight.

I wouldn't bother with a windlass battery, just buy the cable, run it to the bow and forget about it.


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Old 01-12-2015, 20:03   #3
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Thanks Sailmonkey. Is your charge controller standard or MPPT? Ive heard mixed things on both for use in smaller arrays. Any thoughts?
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Old 01-12-2015, 20:18   #4
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Re: Taking Tumbleweed Off Grid..... Solar Advice

https://svsmitty.wordpress.com/ (search for solar)

https://handybobsolar.wordpress.com/
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Old 01-12-2015, 21:07   #5
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Ours is a PWM controller, the dead simple reliable 20 amp version sunguard. We might gain a little from mppt but at the size of our array I don't see the cost benefit.


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Old 01-12-2015, 21:59   #6
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Re: Taking Tumbleweed Off Grid..... Solar Advice

I bought a Rogue 20A MPPT for $225 and it's $45 converter which connects to a laptop to view system logs as desired. Not a very complex or expensive system and has worked well for me so far. I thnk Rogue also sells a 30A controller.

I have 250W w/ 410A bank of Trojan 185s.

Why have a panel/controller setup just for the starter battery and not just a battery switch between the 2 banks? Redundancy?
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Old 01-12-2015, 23:47   #7
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Re: Taking Tumbleweed Off Grid..... Solar Advice

We run our spencer with a 400 ah bank and 200 watts solar array thru a pwm controller. Personally if I were you I would go at least 400 ah on the house bank think 4 days heavy fog/ heavy clouds and rain need power to carry thru that without running the mains to charge 300 watts solar is plenty imo
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Old 02-12-2015, 05:11   #8
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Greetings and welcome aboard the CF, Tumbleweed.
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Old 02-12-2015, 08:05   #9
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Re: Taking Tumbleweed Off Grid..... Solar Advice

The windlass can consume huge amounts of amps when running so any cable supplying it from the battery bank towards the back of the boat may have to be too large to make it worth doing both in terms of cost and weight. With a dedicated battery for the windlass, although a separate solar panel will work, the energy it generates will be wasted once the battery is again full. A good compromise would be to have the solar panel as part of your house bank charging system and use an automatic Voltage Sensitive Relay (VSR) connecting the house bank to the windlass battery. The VSR will need a cable connecting the two batteries but it will only need to be of sufficient size to accept the charging amps instead of the huge consumption of the windlass amps. The VSR will then recharge the windlass battery whenever there is extra voltage on the system.

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Old 02-12-2015, 08:46   #10
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Why AGM?
I went AGM due to sizing constraints, GC batteries are too tall to fit, but unless you can fully recharge AGM's regularly, they will be a liability and cost way more than GC batteries, that are a lot more tolerant of partial SOC cycling, or are at least much cheaper to replace.
I'd spend less on a bigger bank of GC's if I could, my belief is a bigger bank which is discharged to less of total capacity will last much longer, and you have a reserve if you need it.
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Old 02-12-2015, 08:52   #11
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Re: Taking Tumbleweed Off Grid..... Solar Advice

I'd guess his windlass is about 1,000 W max? If so I believe 2 ga wire will cover it easily. Just have to determine the length of run and cost of wire. Some boats may not like the weight of a battery or two being way up there in the bow also. I ran 2 Ga wire for my 1200 W windlass and it has been fine so far, cost of wire vs cost of battery etc. was a wash plus I should never have to replace the wire, the battery I would.
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Old 02-12-2015, 09:13   #12
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Will you have a refrigerator? If not, your 300W solar panels should keep up with the usage you have listed, even at your northern location. If there will be a refrigerator, my (fairly typical) 12V unit draws about 5A when running, or perhaps 40Ah / day in cooler climates. You might just get by.

I agree that any extra solar panels should feed your house bank. Either run heavy wires to the windlass (as I have, and it works fine), or smaller wires and an echocharge feeding a dedicated windlass battery,

By the way, The VSR mentioned by Privilege won't limit the charging current, so you still have to use fairly heavy wires for safety -- they will still be carrying a significant amount of current when the windlass is operating. You can tolerate more voltage drop with it though (so the wires can be smaller than you would otherwise need), since the local battery is there.
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Old 02-12-2015, 10:17   #13
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Hi. I also think that your 300 watt array sounds like a lot but it does depend on where you want to go and at what time of year. I have found that a small wind turbine is a great supplement as it works when the sun is elsewhere. It also works at night.

I think you do need 150-250 watts of solar but just as importantly importantly you need to decide on the type of panel and how you are going to mount it. The choice is of course between rigid aluminium panels (the least expensive), semiflexible (good on bimini top and sprayhoods) and marine modules (expensive but totally reliable).
This Sunworks downloadable solar energy guide is very helpful: www.sunworks.co.uk.

Happy sailing!
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Old 02-12-2015, 10:36   #14
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Both Paul and Pilot raise fair points. There is no wrong method here. Use the following chart as a guide; you can afford a 10% voltage drop on a windlass. You will need to know the rough draw of your anchor windlass and the distance to your battery bank. You can then refer to the chart and work out what gauge cable you will need. Once you have that, you will be in a better position to decide what's best for your set-up.


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Old 02-12-2015, 10:48   #15
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Re: Taking Tumbleweed Off Grid..... Solar Advice

That chart is missing the gauge of wire, I bet the colors correspond to that?

Blue Seas has an excellent app for Apple that will calculate most anything, wire size, fuses, etc.
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