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Old 02-12-2015, 23:32   #31
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Re: Taking Tumbleweed Off Grid..... Solar Advice

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Originally Posted by StuM View Post
An even better rule of thumb is to have 1.5 x watts of solar panels as your daily demand in Ah.

Then size your battery bank to be at least twice your daily demand. I have 800 Watts solar and 1000Ah of storage. The advantage of that is the 800 Watts meets my daily demand and my batteries rarely, if ever, get close to the dreaded 50% discharged even with inclement weather.
I can't argue with that... I wish we had room for another 2 x 150 watt panels but they won't fit. People can make fun of my boat all they want but I want that power! The solar is much more reliable for daily charging than the wind but we are out of space.

So far, the 1.5 rule overall has worked for us but I can definitely see how you could effectively use your formula as well.

The 450 watts of solar would get the poster about 187 Ah a day but the 300 is kinda skimpy at only 125 daily Ah, which isn't even 50% of his bank. And that is here in Florida. I have heard that solar can be cut in half about 40 degrees latitude.

http://docs.engineeringtoolbox.com/d...gram-0degN.png

BTW, if the poster is wondering were these figures come from... the varying "rule of thumb" is to expect about 5 hours of usable power producing light a day from the sun. You get more if you adjust your panels all day and you do capture some at both ends, but 5 or 6 hours is the usual. Its better to be pessimistic and plan for winter sun angles, thus 5 hours vs. 6 hours.
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Old 03-12-2015, 00:08   #32
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Re: Taking Tumbleweed Off Grid..... Solar Advice

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Originally Posted by Tumbleweed34 View Post
Wow, lots of good info here!

The excel solar calculator is awesome! Thanks for that.

Voltage drop chart, Thank you.

As far as refridgeration, we have a dometic cf-50 (kinda looks like a gray cooler). Its AC/DC, it draws .7 amps AC and 7 amps DC (I just looked that info up, ouch!), however it doesnt run that often. If i had to guess I'd say it runs on average 10 minutes an hour, maybe 15 minutes an hour in the summer. So about 42 AH a day in summer. (maybe a Yeti cooler and a block of ice a week could be a viable alternative)

My reason for wanting dedicated panels and batteries for engine and windlass is primarily redundancy and simplicity. I guess I could run the windlass and engine off one battery (just start the engine before I use the windlass so I get the benefit of the altenator). With that said there have been some good points made here about Automatic Charge Relays.
May have to rethink the whole dedicated panels scenario... I'd rather change my mind a few times BEFORE I spend the money.

Why AGM's?
1)I may have to get creative in how they are mounted due to space constraints. AGMs dont spill and can be mounted in any orientation
2)I live on the boat full time and I sleep in the berth that houses the batteries underneath it. The fact that they dont off gas anything will help me sleep better (pun intended). The thought of hydrogen off gassing inches from my sleeping head creeps me out, even if its me just being paranoid.

I'm starting to buy stuff now and will be starting the install on days over 40 degrees thru Jan Feb and March. I'm sure I'll have

Has anyone used the Renogy brand panels on Amazon? The price seems right and the reviews are good, I'd just like to hear if anyone here has any real world feedback. Or has anybody recently bought a different brand of affordable solar panels they would recommend?
Sorry if my response is a bit all over the place...

Thanks for the insight so far, you guys are the best.
I think you are underestimating the fridge consumption. I would guess it will run at least half the time in the south. As well when sailing you will have almost all the loads you do at anchor plus chart plotter and any other nav item to power.

Simplicity? 3 solar systems is not simple!

I would run cables to the windlass from the house bank. All charging should go direct to the house bank. The ACR (VSR) shown will take care of the start battery.

I would also question Agm batteries. Twice the cost, shorter life than flooded very likely, and a lot fussier in charging, especially if you cannot plugging into shorepower regularly. I would either ventilate the under berth battery area to the outside - pretty easy actually - or try and re-locate to the cockpit locker possibly.

Good info on Agm batteries here:
http://forums.sailboatowners.com/ind...choice.124973/

4 GC 6 volt batteries in series/parallel will give you 440 AH or more and is a good cruising bank.

Solar - install as much as you can without it getting in the way. MPPT controllers will give you more from your panels. MPPT vs. PWM Controllers Photo Gallery by Compass Marine How To at pbase.com

Buy a name brand controller - BlueSky, Victron, Morningstar, or Midnite for example.

As far as Renogy panels - Renogy 100w flex panels | SailboatOwners.com Forums
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Old 03-12-2015, 15:51   #33
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Battery type/capacity and how much solar power seem to be generating almost as much fun as anchoring and varnishing!

For ten years we have had solar on our boat. During that time we have cut our consumption from 175 to 75 amp hours per 24 hour cycle.

Nigel Calder has a nice section in his Mech and Elect Handbook that outlines how to determine your daily usage. It's a good place to start.

We have a keel cooled fridge (the Frigoboat unit), all LED lighting, changed the laptop to a SSD (and the current laptop draws <65watts while on and charging). We watch video on our 15.6" laptop screens, which double as chartplotters. They plug into the stereo easily. We have stayed with foot pump water, use an AIS unit in our VHF, no radar.
We use the 36 cell panels (a pair of Kyocera 85watt) into a Blue Sky MPPT controller. I think the new version (3000i) has a second output on the controller. They charge four (2 pairs) of Lifeline group 31 AGM batteries.
We can go at least a week in the Pacific NW winter without hitting 12.2 volts. During the summer we have plenty of power. In warm water (75-80) and hot air (90+) on the east coast, we topped out at about 90-100 amps per day due to the fridge (16-20 aH cool to 36-40aH in hot weather) and extra fans.

The AGM batteries on our boat replaced gels that lasted 9.5 years. We went with these batteries because they will take the full output of our alternator (12si rebuilt to 108amps), which is limited by our regulator to about 80 amps, until almost fully charged. I was very pleased to find that this matched the Lifeline claim, but was disputed by many people I know in the industry. I checked this with a meter a couple of times. But we don't really need to rely on that because of our usage.

In winter we go into deficit by about 25 amp hours per day. Our battery banks total 420, with 210 above the 50% level. We actually see an average of 50+ amps per day from our solar.

If we added radar we would need more. To do that we would need some sort of arch on the stern for the extra panels. Then I'd probably put up three 145-150 watt panels. The arch costs as much as the radar!

During our examination of electrical components we found some interesting things. Our old propane solenoid drew 500ma, our new one 250ma. The MPPT controller we use is not the most sophisticated one, but it uses a fraction of the power my first choice (an Outback unit). The electrical system is really just that, an interconnected whole. If we add radar (or a watermaker) we would then need more panels (and mounting system), a new controller, some new wiring $$$$$$$

I am in the industry, helped scores of people with similar systems, and have found there is no one solution. The balance of use and power generation is different for everyone. That said, a well thought out reduction of demand, and a good solar installation makes things much better!
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Old 04-12-2015, 17:26   #34
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Re: Taking Tumbleweed Off Grid..... Solar Advice

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Originally Posted by Quickbeam View Post
Battery type/capacity and how much solar power seem to be generating almost as much fun as anchoring and varnishing!

For ten years we have had solar on our boat. During that time we have cut our consumption from 175 to 75 amp hours per 24 hour cycle.

Nigel Calder has a nice section in his Mech and Elect Handbook that outlines how to determine your daily usage. It's a good place to start.

We have a keel cooled fridge (the Frigoboat unit), all LED lighting, changed the laptop to a SSD (and the current laptop draws <65watts while on and charging). We watch video on our 15.6" laptop screens, which double as chartplotters. They plug into the stereo easily. We have stayed with foot pump water, use an AIS unit in our VHF, no radar.
We use the 36 cell panels (a pair of Kyocera 85watt) into a Blue Sky MPPT controller. I think the new version (3000i) has a second output on the controller. They charge four (2 pairs) of Lifeline group 31 AGM batteries.
We can go at least a week in the Pacific NW winter without hitting 12.2 volts. During the summer we have plenty of power. In warm water (75-80) and hot air (90+) on the east coast, we topped out at about 90-100 amps per day due to the fridge (16-20 aH cool to 36-40aH in hot weather) and extra fans.

The AGM batteries on our boat replaced gels that lasted 9.5 years. We went with these batteries because they will take the full output of our alternator (12si rebuilt to 108amps), which is limited by our regulator to about 80 amps, until almost fully charged. I was very pleased to find that this matched the Lifeline claim, but was disputed by many people I know in the industry. I checked this with a meter a couple of times. But we don't really need to rely on that because of our usage.

In winter we go into deficit by about 25 amp hours per day. Our battery banks total 420, with 210 above the 50% level. We actually see an average of 50+ amps per day from our solar.

If we added radar we would need more. To do that we would need some sort of arch on the stern for the extra panels. Then I'd probably put up three 145-150 watt panels. The arch costs as much as the radar!

During our examination of electrical components we found some interesting things. Our old propane solenoid drew 500ma, our new one 250ma. The MPPT controller we use is not the most sophisticated one, but it uses a fraction of the power my first choice (an Outback unit). The electrical system is really just that, an interconnected whole. If we add radar (or a watermaker) we would then need more panels (and mounting system), a new controller, some new wiring $$$$$$$

I am in the industry, helped scores of people with similar systems, and have found there is no one solution. The balance of use and power generation is different for everyone. That said, a well thought out reduction of demand, and a good solar installation makes things much better!
Thanks Quickbeam. Really good idea seeing what stuff draws and seeing what the new stuff draws as you replace/upgrade equipment. i'm going to start doing that.
I really had my heart set on radar but I'm thinking now that it might not feasible unless I give up the refer unless...

Furuno has a 15" wireless wifi radar that displays to an ipad. The dome uses much less power (25W) vs Garmin (33.5W) and Raymarines (40W) 18" domes. Just sucks that it only displays to iOS and wont talk to a nmea network. Another concern is viewing an iPad in direct sun, but i guess ifs its bright n sunny I wouldnt need the radar!

Navico has 3g/4g at only 18W but I dont love the user interface of the Simrad/B&G/Lowrance stuff. Might just have to look at the Zues2 again and see if I can learn to like it.

Thanks everybody for your input so far! I will post updates as I start to buy/install items (and hit stumbling blocks) along the way!
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Old 06-12-2015, 01:41   #35
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Re: Taking Tumbleweed Off Grid..... Solar Advice

Take a look at "Firefly Oasis" carbon foam batteries. I think worth every penny.
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Old 06-12-2015, 13:35   #36
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Re: Taking Tumbleweed Off Grid..... Solar Advice

The Firefly batteries look interesting. I did notice the comparison graphs listed "A B C" brands, not actual battery brands and models. That always makes me sit back and think.
Darrell and Nigel seem to be giving some real close attention to the long term use of these batteries. It will be interesting to see how they stand up. Bruce may have latched on to a nice item for us that don't like to live on the bleeding edge of new technology.
The websites do make a good point that AGM batteries are not equal. If you are considering AGM batteries, look carefully at the specifications for the size you are going to use.
Our boat happens to use the group 31 batteries. The brand we use lets us pour at least 80 amps into each bank (2 group 31 - 210aH each bank) until at least 95% charged. This is better than most, and there are variations even within a single brand. We could increase the output of our alternator to 108 amps, but are limited by a single belt. I don't like cleaning belt dust off every few hours. We also usually are fully charged from our solar panels anyway.
Again, thanks for the lead on the Firefly batteries.
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Old 06-12-2015, 17:15   #37
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Re: Taking Tumbleweed Off Grid..... Solar Advice

If the firefly batteries came in a range of sizes and capacities they would be more appealing. As it stands now, they do not let me (and I imagine many others) capitalize on available space, which drastically reduces their usefulness.
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Old 07-12-2015, 13:23   #38
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Re: Taking Tumbleweed Off Grid..... Solar Advice

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Take a look at "Firefly Oasis" carbon foam batteries. I think worth every penny.
Looks like promising technology but $1700 for 4 batterys with just over 400AH...

A: $1700 is almost 2/3 of my solar project budget
B: 4 Group 31s just wont fit where I need them to
C: If $$ wasnt an obstacle I'd probably go LiPo/Lithium ion

I can get (4) 6V Deep Cycle Flooded Marine Battery, 230 Amp Hours, Group GC2 for about about $500 total. I wanted to go AGM but the flooded batteries will fit upright in their spot and the area has active ventilation via a solar nicro/marinco vent. So that will put me at a 460AH battery bank.
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Old 07-12-2015, 13:46   #39
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Re: Taking Tumbleweed Off Grid..... Solar Advice

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Originally Posted by StuM View Post
An even better rule of thumb is to have 1.5 x watts of solar panels as your daily demand in Ah.

Then size your battery bank to be at least twice your daily demand. I have 800 Watts solar and 1000Ah of storage. The advantage of that is the 800 Watts meets my daily demand and my batteries rarely, if ever, get close to the dreaded 50% discharged even with inclement weather.
Thanks Stu & Zboss

I am not quite at 1.5X AH to Watts but the plan now is alot closer to those ratios than my initial proposal of 300AH battery and 300Watts solar. The new plan is 460AH and 640 watts solar, much closer to the ratios above.
3x 160W panels on a hard bimini and 1 160W panel on hard dodger
(both the dodger and the bimini are part of this project as well and dont exist yet)

thanks again to all for the info/insight
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Old 07-12-2015, 14:23   #40
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Re: Taking Tumbleweed Off Grid..... Solar Advice

I would forget the windlass battery,just run wire,a bit expensive initially but it is 'fit and forget' Maybe a Balmar Smart Gauge would be a good idea. The 4 EGC2 house bank and a Echo charge to the dedicated engine battery sounds like a good plan. [same as I have !!] Usually when you are hauling the anchor,the engine is on so its not much of a factor.
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Old 07-12-2015, 14:25   #41
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Re: Taking Tumbleweed Off Grid..... Solar Advice

We have a 315Ah battery bank with 560w solar. Standard controllers, no MPPT

We have a dometic fridge, LED lighting, an onboard PC running 24/7, typical instruments and charge plenty of mobile devices / toys every day. We do not use a laptop or TV but only tablets.
On normal sunny days we run the watermaker for a 4-8 hours but it's a small unit drawing around 5A.
We have enough surplus energy that we use a230v breadmaker every other day.

I never checked daily consumption but the night consumption is typically around 30-40Ah for a 10-11hr darkness period. It mostly depends on the fridge (ambient temperature, how much beer has been refilled, etc).

The battery bank is big enough to bring us through the night. Solar recharges the bank by noon on normal days. With days of rain or fog the batteries are at least partly recharged by sunset. The worst day so far ended with 22Ah deficit, buy that was without watermaker and bread maker of course.
That small battery bank should serve us about a week in bad weather.

In case we ever have to recharge using the engine we have added a b2b charge controller to minimize engine time.
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