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Old 04-10-2013, 13:16   #31
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Re: Solar Panels

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Originally Posted by scoobert View Post
a few things here.
first, who owns a VCR?
second, laptops can use over 150watts, when being used.
my personal laptop uses about 250watts at full load.
fridge is not mentioned, and uses the most power.
I agree with you about the VCR and fridge, but the laptop numbers are very high.
A typical older generation 15 inch laptop will use about 3.2-4 A on average, say
45w. A notebook about 1.2A or 15w a tablet about 0.5A or about 6w.
These figures are for a DC to DC converter if you use an inverter expect 20-30% more.
Some of the old processors were very power inefficient but 150-250w is way more than most users will see as an average.
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Old 04-10-2013, 15:25   #32
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So why would having 1,000W of solar be a bad thing? I see a lot of people say it's not necessary, but if it takes care of the fridge/freezer and everything else...?

And wouldn't you still get roughly 500W on a cloudy day?

...what's the problem?
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Old 04-10-2013, 15:51   #33
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Re: Solar Panels

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Originally Posted by noelex 77 View Post
I agree with you about the VCR and fridge, but the laptop numbers are very high.
A typical older generation 15 inch laptop will use about 3.2-4 A on average, say
45w. A notebook about 1.2A or 15w a tablet about 0.5A or about 6w.
These figures are for a DC to DC converter if you use an inverter expect 20-30% more.
Some of the old processors were very power inefficient but 150-250w is way more than most users will see as an average.
I would agree that my laptop is the biggest user on my boat. I'm looking towards a tablet for the advantage of low power draw and to act as a chart plotter. Two birds with one stone, so to speak. I took great care in the insulation process of my fridge. 1" of Areogel with 3-4"s of pour foam around that. It runs 5-6 minutes and off for 25 minutes. The refer is something you can control through proper insulation. The laptop however
I have 300 watts of panels, whose sun angles I can adjust. I have a 400 watt inverter and not too many toys. With the 300 watts and the fact I seem to motor a little everyday, I keep up quite well. I'll be in Mx in a few weeks which has flucky winds at best, so I suspect more motoring
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Old 04-10-2013, 16:24   #34
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Originally Posted by MBLittle View Post
So why would having 1,000W of solar be a bad thing? I see a lot of people say it's not necessary, but if it takes care of the fridge/freezer and everything else...?

And wouldn't you still get roughly 500W on a cloudy day?

...what's the problem?
No problem. In fact, if you have the deck real estate to have enough panels, you should put more on. It is cheaper to add more panels than swap a PWM for an MPPT.

We have 970 W of panels, no generator, 880 Ah of batteries to get us thru the cloudy days and only a PWM controller for one third of the panels. The rest are in parallel connected direct to the battery bank with breaker switches in the cockpit.

Right now it is 8:20 am, 30 A pumping in and in a couple of hours I will switch off one bank of panels. Maybe a second bank will be turned off later. It feels like turning off a nuclear plant from the national grid. You need to be alert though and have a battery voltage reading at least in the cockpit or you will cook the batteries one day.

It has worked fine for us for 3 years of live aboard but I would not recommend it for everyone.
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Old 04-10-2013, 16:35   #35
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Lots of panels also means you buy cheap inefficient fridge and freezers instead of throwing money at expensive marine stuff. Excess panels leads on to $ savings in other areas of your boat.
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Old 04-10-2013, 17:03   #36
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Re: Solar Panels

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Originally Posted by MBLittle View Post
So why would having 1,000W of solar be a bad thing? I see a lot of people say it's not necessary, but if it takes care of the fridge/freezer and everything else...?

And wouldn't you still get roughly 500W on a cloudy day?

...what's the problem?
It's not 'a bad thing' at all and a 'lot of people' also think shopping at K-Mart buys quality.

Provision for redundancy and the inevitable shading losses, no need to be a minimalist in your everyday life unless you so choose. Leave that to the frontiersman wannabees.

Why should you limit your computer or other electronic device usage if you don't have to? Play computer games, watch DVDs, word process, collate and edit photos etc without equipment imposed limits.

Use at least 24v [pref.higher V + MPPT] panels and add a 24v heater element to your hot water tank for when batts are full, run a watermaker etc.

There are plenty of uses for electricity on board if you have it, aren't there?

If one can't fit or doesn't want all that power, their choice, if one can fit the panels/system and wants that power, their CHOICE!

Some do not have that choice due to size or budget. Some choose a minimalist philosophy. I'm not one of the latter for sure.

You choose what's best for you, the more power the more options.

Cheers,
Mac
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Old 04-10-2013, 19:03   #37
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Re: Solar Panels

Thank you to all of you who responded and thanks for refraining from condescending discussions. We will go with more than less because increasing the size is relatively inexpensive and cheaper to do now as opposed to later. I gather the MPPT technology is superior than the legacy chargers so will also install one of these. I was amazed at the price difference online vice in store for these panels.

Again thanks for all the advice and education.
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Old 12-10-2013, 09:43   #38
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Re: Solar Panels

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4x50w will give a bit more output on a boat than 1x200w for the reasons mentioned, but 4x50w is generally physically larger than a single 200w panel because of panel framing etc. The high efficiency panels increase the gap further and are only available in large high wattage panels.
On one website I found Kyocera 250w at 30-36v for about $275. The same site has Solartech 85w 18-25v for $200/ea, so I could get 3. Or 65w 18-25v also $200/ea. Clearly the price per watt goes down with the bigger single panels, so the question is, is there any good reason to go with more smaller rather than 1 larger?
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Old 12-10-2013, 10:10   #39
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Re: Solar Panels

With more panels adding up to the same wattage the output tends to be slightly greater, but the difference is small. As you have noted more small panels tends to be more expensive (but make sure you factor in delivery costs large panels often have a high delivery cost due to a glass surcharge). Multiple small panels are also physically larger.
Large panels tend to be higher voltage so you have to use a MPPT controller.

In general despite all the pro and cons what physically fits the desired location with the most number of watts in the easiest any cheapest way tends to be the dominating factor. Cost is changing rapidly and varies considerably in different locations so it is difficult to give general advice.

Always go for more watts if you have a choice.
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Old 12-10-2013, 10:29   #40
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Re: Solar Panels

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I've read through a number of these threads, how many watts solar, how big a house bank, etc. My take away is usually the same.

You can estimate your energy consumption all you want, but at the end of the day space limitations and cost are the factors that will ultimately govern what people end up with.

One of these days I'll have to figure out how to set up a poll, would be very interested to see what most people have set up on a forty footer. Somehow I imagine most people end up with very similar set-ups on similar sized boats, but I could be wrong.
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Old 12-10-2013, 19:21   #41
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Re: Solar Panels

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Originally Posted by Empty Pockets View Post
On one website I found Kyocera 250w at 30-36v for about $275. The same site has Solartech 85w 18-25v for $200/ea, so I could get 3. Or 65w 18-25v also $200/ea. Clearly the price per watt goes down with the bigger single panels, so the question is, is there any good reason to go with more smaller rather than 1 larger?
Flexibilty? Currently I have two panels hanging to keep my batteries charged while I'm away from the boat traveling. My other two are stowed below. Smaller panels are easier for me to handle and stow. If one of my panels break or fail, I have three more that work. Mine are mounted so I can tilt and move them independently. That was my logic based on the size and configuration of my boat.

BTW, I walk the docks and look, take pics, and talk to other sailors before a project. I usually get at least one free beer out of the strolls.
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Old 14-11-2013, 13:13   #42
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Re: Solar Panels

I have head two Kyocera 135W panels with a single BlueSky 2000 MPPT on my Yankee 30' for over three years. On a cool sunny afternoons, I have seen them pumping 18.2A into my batteries. I have cruised the Med for two seasons and when on rare occasion I had to run the engine to charge my batteries, it was because of the darn TPPL AGMs. Sorry about whining, but the two larger of the four lasted about a month. After that they wouldn't keep or take charge. (when I returned to Florida, I got two brand new ones under warranty, one of them failed again since). Anyway, I've been following the LiFePO4 enthusiasts here on the cruisers forum and plan on going LIFePO4 next. Hence solar related question:
If I added one or two smaller solar panels, say 80W size, should I sell the BlueSky2000 and buy three or four smaller MPPTs (capable of being set up for the LiFePO4 bats) so each panel has it's own regulator, which I hope would mitigate some of the problems with shading. Anyone knows of suitable, modern, cheap MPPT for 140W source panels?

Stan
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