Taking Tumbleweed Off Grid..... Solar Advice

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[Paul Elliott]

I added the wire gauge chart to the Voltage Drop chart. (one of the vast powers of a moderator!)

[mramoo]

One thing that I have not seen in your power usage is a watermaker. When you take your boat to the mooring ball, are you going to tote water to your boat or have a watermaker? Toting 5gal jugs of water can become a real pain.

[Tumbleweed34]

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.

[Tumbleweed34]

mramoo: no plans for a water maker yet. The plan is to motor over to the fuel dock when we need to refill our water tank. We have done a New England winter living on board: YES, hauling 7 five gallon jury cans off water in a dock cart on an icy dock sucks and transporting 5 gallon jury cans in a dink cant be much fun either. Its amazing how long you can stretch 35 gallons when you have to haul every ounce of it!
It may become an option once we start cruising full time but even then we will be coastal cruising, maybe a day or two max between ports. And even then we just have a sink, which doubles as a washdown (hose threads onto faucet) no shower on board.
I was under the impression watermakers were more of a passage making item? Dont get me wrong, Id love to have one, its just not on the list of priorities now.

[newhaul]

We installed the 200 watt kit from windy nation 200 Watt 200W Solar Panel Kit with LCD Solar Controller 12 24V RV Boat Off Grid | eBay
It seems to be doing great for us running full led lights and a 12v refer that draws just about 4 amps on medium high speed.

[barnakiel]

Is there enough space and low enough on a Tartan 34C to keep a 300 Ah battery bank? It is quite some volume and weight (in lead technology).

I think 300W solar on a 300Ah bat bank is pretty mickey mouse (no offense meant).

We have 150W panels on a 100Ah bank and we are those very very very frugal sailors you can read about in the 'it can't be done' threads. I am just about to go 200W panels and mppt way. I would also go lithium if not for the price.

If you do have 300Ah bank and if you do want to seriously use solar as your power source, I would actually double the solar feed.

If you think you do not need so much energy ... then why not cut your bat bank in half?

Not to say there is only one way to skin a cat. Just our one-off, isolated experience.

Have fun building your kit,
b.

[Tumbleweed34]

Originally Posted by newhaul

We installed the 200 watt kit from windy nation 200 Watt 200W Solar Panel Kit with LCD Solar Controller 12 24V RV Boat Off Grid | eBay
It seems to be doing great for us running full led lights and a 12v refer that draws just about 4 amps on medium high speed.

Just checked it out and put it on my watch list on eBay!

[zboss]

I personally believe a good rule of thumb is to have 1.5x watts of solar panels as you do total Ah in your batteries. Assuming you have properly sized your battery bank.

So, 300 Ah's of batteries would mean having 450 watts of solar.

You have to account for multiple days of clouds, winter sun angles, bird crap, dirt, aging wiring, aging batteries, etc... It takes about 20% more energy to charge as you take out to reach parity. You occasionally want to be able to fully charge those batteries as well.

It sucks to be at anchor and always be running out of energy.

We have 560 watts of solar and a 400 watt wind generator for our 600 Ah's of batteries. I wish we could add another 300 of solar.

[newhaul]

Originally Posted by Tumbleweed34

Just checked it out and put it on my watch list on eBay!

One good thing with that unit is the controller will handle expansion to 400 watts in the future.

[Tumbleweed34]

Originally Posted by barnakiel

Is there enough space and low enough on a Tartan 34C to keep a 300 Ah battery bank? It is quite some volume and weight (in lead technology).

I think 300W solar on a 300Ah bat bank is pretty mickey mouse (no offense meant).

We have 150W panels on a 100Ah bank and we are those very very very frugal sailors you can read about in the 'it can't be done' threads. I am just about to go 200W panels and mppt way. I would also go lithium if not for the price.

If you do have 300Ah bank and if you do want to seriously use solar as your power source, I would actually double the solar feed.

If you think you do not need so much energy ... then why not cut your bat bank in half?

Not to say there is only one way to skin a cat. Just our one-off, isolated experience.

Have fun building your kit,
b.

No offense taken, I have the same concerns with fitting the batterys. Its currently configured to hold 2 group 31 house batts and the group 24 starting batt under the port berth. The group 31's are 105 AH each. Im thinking I might be able to move the starting battery to the nav station or the head off the pilot berth (both close proximity to the yanmar) and shoe horn a third group 31 under the berth. I just have to get the measuring and figuring done. All this is roughly centered in the keel area, so the weight will increase by one battery but is fairly well centered and low.

Is it the 1 to 1 ratio of solar watts to ah storage that is mickey mouse?
Is a 1.5 to 1 ratio like yours more efficient?
I was thinking along the lines of: I can fit 300AH of batteries and I can fit 300 watts without covering the boat w panels. Would I be better off with 200AH and 300Watts of solar? Is this an efficiency thing? I dont have room for more panels but I can remove a battery if that some how will be better.

I applaud you for being very very very frugal ( i assume you are referring to power consumption). However, I am not nearly as frugal as you. This is the system I think I need, to run the stuff that I listed... are you running loads similar to what I listed on 100 AH battery? I do have solar powered led lanterns and a bluetooth rechargeable speaker and smaller lipo portable batterys that all charge in the portlights off small portable solar panels and probabably could get rid of a battery. But i dont really want the "camping experience" everyday. So if I cant add more panels whats the worst that happens with 300 solar w 300 AH? Again, not being a antagonistic, just curious? Maybe I have to run the engine occaisionally, or be a little more frugal?

I too would go lipo if not for the cost and would probably be looking at semi rigid panels if not for the cost. (and would probably not have 40+ year old boat if it were not for the cost)

[Tumbleweed34]

Originally Posted by zboss

I personally believe a good rule of thumb is to have 1.5x watts of solar panels as you do total Ah in your batteries. Assuming you have properly sized your battery bank.

So, 300 Ah's of batteries would mean having 450 watts of solar.

You have to account for multiple days of clouds, winter sun angles, bird crap, dirt, aging wiring, aging batteries, etc... It takes about 20% more energy to charge as you take out to reach parity. You occasionally want to be able to fully charge those batteries as well.

It sucks to be at anchor and always be running out of energy.

We have 560 watts of solar and a 400 watt wind generator for our 600 Ah's of batteries. I wish we could add another 300 of solar.

That makes sense... according to the solar calculator chart I need about 300AH, but i was generous with my estimates and the chart added 20%. I might able to reconfigure and figure out how to get 450 watts on there. I suppose 400 would be better than 300 if i cant get to the 450 watts.

[Tumbleweed34]

Originally Posted by newhaul

One good thing with that unit is the controller will handle expansion to 400 watts in the future.

I saw that too. Based on the last few post my "future expansion" may be sooner than anticipated.

[StuM]

Originally Posted by Tumbleweed34

Is it the 1 to 1 ratio of solar watts to ah storage that is mickey mouse?
Is a 1.5 to 1 ratio like yours more efficient?
I was thinking along the lines of: I can fit 300AH of batteries and I can fit 300 watts without covering the boat w panels. Would I be better off with 200AH and 300Watts of solar? Is this an efficiency thing? I dont have room for more panels but I can remove a battery if that some how will be better.

Remember that unless you are using Lithium, only 50% at most of your Ah storage should be considered useable. So you have 300W to maintain 150 Ah of usable power. An estimate of the daily power from 300W under good conditions would be about 125 - 150 Ah per day. So it's marginal if that is your daily usage. A 1.5:1 ratio with 450W of solar would give you up to another 60-75 Ah per day incoming. More importantly it provided additional cover for those cloudy/rainy days when you don't get as many Ah out of those panels.

If you need more that 125-150 Ah on a daily basis, you need to increase both storage and generation capacity.

If you get rid of one battery without changing your daily demands, you will shorten your battery life dramatically by deeper discharging them.

[StuM]

Originally Posted by zboss

I personally believe a good rule of thumb is to have 1.5x watts of solar panels as you do total Ah in your batteries. Assuming you have properly sized your battery bank.

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.