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Surprise!

So Bob, . . .

I'm curious to know if you spread those cardboard mock ups around, and if there was any deck left to walk on, after you did? Wouldn't you rather stack sails with all that deck space?

For $1300, I'd be tempted to put a nine foot (above deck) spar in your mizzen hole, with a modest wind generator on top, and have a similar wattage but, night and day, overcast, or not.
 
I did and there's enough available real estate, but at least one panel would be partially shaded at any given time. I wouldn't use the old 42 watt panel, since one of the big ones would fit across the dodger in its place. Another panel could lay across the seahood, one could lay flat on the afterdeck and there's enough space elsewhere to move one or two around to avoid shading from the sails.

But you know, the spar is a great idea. Maybe I could find a taller one and have a mizzen - I always wanted a yawl!
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Hey Bob, I was going over Surprise's updated energy budget. It looks like you've got about 48 hours before you NEED to charge. I think if you were willing to put up with running the engine every day until you got into the sun, you could probably go with two of the solar panels and one regulator, plus Jackie's. Once you're in the sun, two of those panels should almost keep up with you.
 
Hi Rob,

I tweaked it a bit more, getting rid of the small panel and cutting down the alternator output to what I think I'll actually see. I'd rather use the space on the dodger for one of the new, big panels. And unless the batteries are really flat the alternator output drops rapidly, so 40A seems more realistic as an average. This latest budget shows charging every 24 hours and is more in line with what you originally predicted.

Greg N suggested SunPower's 110W panels that are rated at 18.8 volts* (and 5.9A each). My understanding is that the MPPT controllers convert excess voltage into additional current, so the 110W panels could be more efficient. So maybe three 110W panels that are less likely to be shaded, instead of four 160W monsters, and charge every day instead of every other day. What do you think?

* Edit: I just checked, and the 160W Renogy panels you suggested are rated even higher @ 19.1 volts. Hmm, now I'm confused...
 

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I have to replace my batteries this year and I was thinking of going with the carbon foam. I've read that you don't want to charge them at more than 14.4 volts. is this true. I have found that with the MPPT controller I have it will charge my lead acid at more than that. Do you set up the controller differently with the carbon foam?
 
Hey Bob, I'm chuckling at your confusion because it's a confusing subject. Here is a little online calculator that may help: http://www.ohmslawcalculator.com/ohms-law-calculator For solar panels, there really is no rating convention. For example, 100-watt panels are popular. Manufacturers can easily "rate" a panel as 100W by adjusting the voltage it's rated at. If all panels were rated correctly (in my mind that would be 14.1V) then you could easily tell the output. So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.

I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
 
Steevee said:
I have to replace my batteries this year and I was thinking of going with the carbon foam. I've read that you don't want to charge them at more than 14.4 volts. is this true. I have found that with the MPPT controller I have it will charge my lead acid at more than that. Do you set up the controller differently with the carbon foam?
Click to expand...

Yes. 14.4 volts is what they want. The Victron controllers should allow me to change the settings. The "Smart" version includes Bluetooth so you can do that from your phone. Jackie's version can accept a Bluetooth dongle so you can at least see what the controller is doing. I haven't bought anything yet and will investigate all this before I do.
 
robtryon said:
Hey Bob, I'm chuckling at your confusion because it's a confusing subject. Here is a little online calculator that may help: http://www.ohmslawcalculator.com/ohms-law-calculator For solar panels, there really is no rating convention. For example, 100-watt panels are popular. Manufacturers can easily "rate" a panel as 100W by adjusting the voltage it's rated at. If all panels were rated correctly (in my mind that would be 14.1V) then you could easily tell the output. So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.

I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
Click to expand...

This reminded me of my post about the sizes of toilet paper rolls.

Since the SunPower panels are a foot shorter, they open up more options on deck. But yes, they're more money per watt.
 
I do apologize for not reading through all of the 26 other pages....but I was just wondering if you were a big fan of Gomer Pyle and just wanted to hear the call to your boat over VHF..."Surprise, Surprise, Surprise..."

Bob lives 3 doors down from me, so he can beat me personally, the rest of you don't need to get po'd.
 
Power is power. The controller takes the voltage and converts it to an acceptable voltage for the battery. It doesn’t matter if it’s 22 volts or 17 volts. The 100watt panels in your example all produce 100 watts of energy. The controller is the key.
robtryon said:
Hey Bob, I'm chuckling at your confusion because it's a confusing subject. Here is a little online calculator that may help: http://www.ohmslawcalculator.com/ohms-law-calculator For solar panels, there really is no rating convention. For example, 100-watt panels are popular. Manufacturers can easily "rate" a panel as 100W by adjusting the voltage it's rated at. If all panels were rated correctly (in my mind that would be 14.1V) then you could easily tell the output. So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.

I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
Click to expand...
 
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I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
Click to expand...
I know of several returns on the Ronogy panels..... but at least I think they will be around to warranty their products. Unless the physical sizes are a factor there are few reason to buy anything but the Sunpower branded panel. 110w (not the 100 as it's voltage is lower) for <$250 from Amazon or others but you still need a backing. 7amps output using an MTTP.
 
So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.
Click to expand...
Hmmm..... its the opposite with an MTTP controller. You need the higher voltage since the controller is really a DC-DC converter. Same amps, more voltage = more power.
 
No no no
P=iv
If the voltage is higher, then the amps are lower, and vice versa.
solosailor said:
Hmmm..... its the opposite with an MTTP controller. You need the higher voltage since the controller is really a DC-DC converter. Same amps, more voltage = more power.
Click to expand...
 
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That looks like a good article, neighbor - I'll read it carefully.

I already have the batteries so that's decided. The 110W SunPower panels and 160W Renogy panels are almost identical voltage but the 110W panels give me more placement options - and I'll probably go with three vs. four. Rob and I are currently (pun intended?) working on properly setting the new alternator regulator to optimally charge the new house bank. Then I'll re-focus on the solar charging.

Solo, I plan to move the panels around on deck for optimal sun exposure, using ties to lash them down. There's enough deck area to avoid stepping on them. Do I still need backing in that case?

At the end of the day these posts will hopefully be helpful to those reading this thread.
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Yes, the panels are way to flex to even move carefully with no wind and at a minimum should have the twin wall polycarbonate backing.

The 100W & 110W Sunpower panel are both rated at 5.9A @ 17.1V & 18.8V respectively so multiplying those you get 100&110W. However when using, for example the Victron MPPT controller, you need 5V delta to even start charging.... that 1.6V delta in panel output makes a big difference in actual output.
 
I'm reading this exchange re: solar panels and controllers with interest. I'd love to see a $$$ / amps generated comparison.
 
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