How much solar panel power is enough?

[s/v Jedi]

Originally Posted by Bash

I disagree. If those three panels are not enough to achieve energy independence, then what you really need to do is invest in getting your consumption down. Easy to do with such things as LED lightbulbs. And this will require much less investment than building an arch and acquiring two more panels.

Honestly, 750 watts is a lot of power. And you've got a huge battery bank by most cruisers' standards. You'll be able to survive back-to-back cloudy days in the Caribbean without any problem. And, if once per year the batteries need a bit of a boost, you can always run the engine for an hour or two.

You think so?! You would tell somebody to stop playing rock music, watching big screen movies and have the computer running to download those 24h/day, instead of buying another panel?

The other guy might not be roughing it as much

[hellosailor]

"This presents starboard panels to the rising sun while shading port panels. "

Nick, it sounds like you've got the panels hanging down outside the lifelines, or in some other configuration that you forgot to mention actually cuts the effective size of your array in half?

They are not all simply flat and level?


Bash, you know, it might be time to drop the L-bomb. You know, replace the lead acid batteries with Lithium, and put 4x the capacity in the same space, so all those sunny days can be stored up and the batteries will never need to deep cycle, and even when they do, they'll last forever. (Glibly ignoring all the other question$ about lithium.)

[Bash]

Originally Posted by s/v Jedi

You think so?! You would tell somebody to stop playing rock music, watching big screen movies and have the computer running to download those 24h/day, instead of buying another panel?

The other guy might not be roughing it as much

I don't mind a bit of rock, as long as he's playing it on an acoustic guitar.

(And he should realize that everyone is roughing it a bit in comparison to s/v Jedi, which I understand is a converted battlestar complete with a functioning holodeck.)

[Bash]

Originally Posted by hellosailor

Bash, you know, it might be time to drop the L-bomb. You know, replace the lead acid batteries with Lithium, and put 4x the capacity in the same space, so all those sunny days can be stored up and the batteries will never need to deep cycle, and even when they do, they'll last forever. (Glibly ignoring all the other question$ about lithium.)

Good thinking. I understand that Boeing is selling off some slightly used Lithium banks, cheap.

[s/v Jedi]

Originally Posted by hellosailor

Nick, it sounds like you've got the panels hanging down outside the lifelines

Yes, I'm the kind of guy who would do that

You could just ask what I mean when you don't understand what I write

[s/v Jedi]

Originally Posted by Bash

I don't mind a bit of rock, as long as he's playing it on an acoustic guitar.

(And he should realize that everyone is roughing it a bit in comparison to s/v Jedi, which I understand is a converted battlestar complete with a functioning holodeck.)

Oh.. has that boatman guy been talking?

But really it isn't so bad but yes we got a lot of sound & vision aboard, among other things

[roetter]

Originally Posted by noelex 77

You would be better to adjust the rebulk voltage.
With an appropriate setting it cause the controller to initiate another bulk phase if the batteries become discharged.
The default setting on the Outback is very low (6v) which effectively disables this feature.

Thanks. I will look into that.

[barnakiel]

It all depends how grey your grey day is.

I noticed huge differences between a sunny and an overcast day (we have a RT dedicated solar amp monitor in line). Thick overcast virtually nulls solar output.

b.

[s/v Jedi]

Originally Posted by barnakiel

It all depends how grey your grey day is.

I noticed huge differences between a sunny and an overcast day (we have a RT dedicated solar amp monitor in line). Thick overcast virtually nulls solar output.

b.

Ah yes, I need to add to my figures above that we are in the tropics

[Sabbatical II]

I tried to calculate all the numbers and get the solar right before we built our current boat which we launched in July 2012. When that was too hard and too inconclusive, I just got out Nigel Calders' Boat Electrical system book and we did exactly as he suggests. My aim was to build a 12v boat and be totally solar dependent without needing to run the engine or have a generator of any kind or needing an inverter for AC power. I think we've achieved that thanks to Calder's book. We have only 320w of solar mounted on a stern arch. We have a 660ah house battery bank. All lights are LED and all other electronics are the latest in low draw modern appliances. The lowest I have seen the bank drop to has been 530ah and this was after 3 consecutive cloudy days with no sun. We don't worry about leaving lights on because with all LEDs, power usage is so small that it doesn't make any difference. We leave the fridge on 24/7 and even at the marina I do not connect the AC power. I have a $30 Dick Smith (think Walmart) inverter that plugs into a 12v socket to charge my laptop every few days. The biggest advantage of having a good electrical system is that I don't have to be harping on about "please turn that light off" all the time. Wives(1) and visitors don't have to reprogram from their shoreside thinking. Running as a 12v boat also saves a lot of complication and I've yet to see it's downside.

[S/V Alchemy]

Originally Posted by s/v Jedi

Here are the numbers for the Caribbean as observed aboard Jedi:

- 660W solar array
- Outback MPPT controller
- 6x Trojan L16 batteries in 12V config for 1,200Ah

- 24h statistics as recorded by the controller:

Sunny day: 2.5kWh
Overcast day: 1.2kWh

This changes month to month too. You can find tables that show radiation for each month of the year for each area in the world.

cheers,
Nick.

That is phemenonally close to what I'm installing this summer.

I suspect we both require ice cubes.

[Bash]

Originally Posted by S/V Alchemy

I suspect we both require ice cubes.

Yep. Ice cubes and one of those constant-flow water slides off the roof.

[hellosailor]

Bash, Boeing has no plans to sell off their incendiary devices. Armor plate, separated cells, titanium vent tubes....I think they've hired the Mad Bavarian Engineers from BMW.

But seriously, there's that other incredibly long thread about LiFePO4 cells, a variant that supposedly are more faithful than Lassie and totally immune to, ah, unexpected behavior. Why Boeing prefers not to use them...and why no "brand name" vendor is making them, these are of course interesting questions.

Kinda like "Wilbur, that thing will never get off the ground!"

[bene505]

Just as a side note on some boat work I'm doing that is related to this thread... During the day, I'm going to put extra available power into the freezer compressor, with a second thermostat set at a lower temperature. The goal is to never have the freezer run at night. That eliminates a lot of battery draw-down.

Snug fitting foam blocks inside the freezer decrease the internal (cavernous) space and increase insulation on all walls and top. The holding plate is big. I may add a container or two of non-toxic antifreeze diluted accurately to freeze at the lower temperature.

Regards,
Brad