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Old 19-04-2019, 11:46   #46
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Re: How Many Watts of Solar?

Just to run your lights, laptop, and microwave you won't need much solar at all.

Maybe one 100 watt panel or smaller through a PWM controller to a couple 12 volt Deep Cycle Batteries in parallel would work fine.

Then you can add as your power requirements increase if they do increase.

Mine have decreased since I have now bought that 12 volt fan.

I also have an autopilot but it uses almost no power at all and it's usually during the day when I'm using it so it's running on solar only usually

You could always ditch that microwave and use your stove or a propane hot plate. Microwaved food isn't too got for you anyway
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Old 19-04-2019, 12:37   #47
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Re: How Many Watts of Solar?

10w per foot of boat per person on board.
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Old 19-04-2019, 13:11   #48
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Re: How Many Watts of Solar?

Microwaves suck a lot of power. If your boat already has propane, use that when you aren't hooked up to shore power.
Someplace in the thread, a poster mentioned turning on their inverter to grind coffee. Go to a second hand store and pick up a couple of old German hand coffee grinders. They last nearly forever and do a great job grinding. Their sound is also far more pleasant than the high pitched whine of electric grinders,
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Old 19-04-2019, 13:32   #49
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Re: How Many Watts of Solar?

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10w per foot of boat per person on board.
There are so many problems with that estimate.
According to your assesment you would need 820 watts solar on my spencer 42
But we did just fine with 200 watts with 2 people onboard. Referigeration and all.
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Old 19-04-2019, 13:36   #50
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Re: How Many Watts of Solar?

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Microwaves suck a lot of power. If your boat already has propane, use that when you aren't hooked up to shore power.
Someplace in the thread, a poster mentioned turning on their inverter to grind coffee. Go to a second hand store and pick up a couple of old German hand coffee grinders. They last nearly forever and do a great job grinding. Their sound is also far more pleasant than the high pitched whine of electric grinders,
I agree with the comments about microwaves
But to be a " power nazi " wrt to simply grinding coffee especially in these days of solar panel efficiency is just a bit over the top .
A better thing would to convert all lights to LEDs to have that power to grind your coffee or even run a rice cooker would be a much better idea imo
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Old 19-04-2019, 14:23   #51
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Re: How Many Watts of Solar?

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Well with 2 and half hours of cruising experience you clearly have more cruising experience than some self professed experts.
Yes that’s waaaaaaaaay up there in real boat time. Moves me firmly beyond the “expects” and into the advanced liar and idiot level.
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Old 19-04-2019, 14:53   #52
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Re: How Many Watts of Solar?

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There are so many problems with that estimate.

According to your assesment you would need 820 watts solar on my spencer 42

But we did just fine with 200 watts with 2 people onboard. Referigeration and all.


I think his estimate is at least as logical as the 20% of purchase price per yr to maintain a boat
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Old 19-04-2019, 15:09   #53
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Re: How Many Watts of Solar?

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I think his estimate is at least as logical as the 20% of purchase price per yr to maintain a boat
There are to many variables in the purchase price of a boat and the cost of maintance that there is also no way to apply a specific formula.
Beyond the basic of watts per amphour of capacity for recharging there are many variables in recharging batteries that several questions need to be answered beyond that basic . Like i posted earlier.
What usage? What location ? Use style like full time cruising or weekend use?
And a rather important variable is battery chemestry.
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Old 19-04-2019, 15:45   #54
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Re: How Many Watts of Solar?

WoW! Holy Crap! I didn't expect so many answers. Thank you all, even those who some here call idiots. I figured out my daily ah at anchor and underway and it looks like 530 Watts is the magic number including 20% added in for underestimating my estimate. Guess I'll install 2-300 Watt panels to be safe.


Thanks again.
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Old 19-04-2019, 15:52   #55
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Re: How Many Watts of Solar?

So ................ 600w

:-)
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Old 19-04-2019, 16:02   #56
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Re: How Many Watts of Solar?

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I agree with the comments about microwaves
But to be a " power nazi " wrt to simply grinding coffee especially in these days of solar panel efficiency is just a bit over the top .
A better thing would to convert all lights to LEDs to have that power to grind your coffee or even run a rice cooker would be a much better idea imo
I wasn't intending my hand coffee grinder recommendation for power nazi purposes. I've just been hand grinding coffee since I was a little kid sitting on my father's lap. That was a really long time ago.
It takes the same amount of time as using an electric grinder. It's far more consistent in getting a good grind (I hate it when a house guest grinds coffee in my electric grinders (none on my boat) and I see a pile of whole beans in my drip basket. Coffee beans that are broken in half or thirds don't please me either.
And - as I said in my first comment- that high pitched electric whine first thing in the morning is unpleasant for me.
Maybe it reminds me of dental procedures.
To each their own, no biggie, I just have my decades old preferences on making a good cuppa coffee.
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Old 19-04-2019, 16:07   #57
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Re: How Many Watts of Solar?

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So ................ 600w

:-)

Yes sir....along with the proper battery setup etc.
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Old 19-04-2019, 16:42   #58
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Re: How Many Watts of Solar?

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The next change will be 6 volt batteries close to 200 ah each. I have two 12 volt 80 ah batteries in parallel now.
Two 235 amp hour 6 volt batteries in series equals one 235 amp hour 12 volt battery.
I have 8 of them. Which gives us four time 235 amp hours. (Not 8 times.)

About 900 amp hours is very good if you have the space for 8 batteries.
I also carry two starting batteries (in parallel) that never do anything except run the engine.
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Old 19-04-2019, 16:49   #59
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Re: How Many Watts of Solar?

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To each their own, no biggie, I just have my decades old preferences on making a good cuppa coffee.
I do carry a hand grinder. But with a big inverter that we almost never use - I grind fresh coffee. I turn on the inverter, grind for 20 seconds, and turn the inverter off. Very little power needed.
It is nice to have the inverter for power tools. But most newer power tools use a battery. I can charge the batteries with a 100 watt cigarette-lighter inverter. So really not much need for the big inverter.
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Old 19-04-2019, 16:51   #60
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Re: How Many Watts of Solar?

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Two 235 amp hour 6 volt batteries in series equals one 235 amp hour 12 volt battery.
I have 8 of them. Which gives us four time 235 amp hours. (Not 8 times.)

About 900 amp hours is very good if you have the space for 8 batteries.
I also carry two starting batteries (in parallel) that never do anything except run the engine.
900ah Fla gives about 450 usable that's good so you need about 900 watts solar to charge that if just solar.
Now switching to Lfp you would need estimated 600 ah capacity at about 25% of the weight . And due to charging acceptance you could likely get by with 400 watts running thru an mppt controller.
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