Challenges with Solar on boats

[newhaul]

Originally Posted by socaldmax

If you did that, you'd be wasting your time, money, and valuable space on your boat. Why waste time bolting down 3 100w panels when you can simply bolt down 1 300w panel?

As I tell customers, I don't even pick up the drill for panels smaller than 200w.

Based on the prices at my distributor, 100w panels cost $65 (65cents/watt), his 280w panels are the big bargain at $86 ea (30.7 cents/watt), the 230w panels are $72 (31.3 cents/watt) and the 320w panels come in 3rd at $119 ea (37.2 cents/watt.) Why pay more for less? Another nice side benefit is I can use a cheap 20A controller connected to each 320w or 280w panel and get 20A or close to it at peak summer hrs and not worry about series connected panel shading or even shading losses in parallel from the loss of MPPT efficiency. Large panel efficiency and one controller per panel gives max MPPT harvest.

Finally, the 100w panels are quite often less efficient than the 300w panels, so not only do they take up a lot more space, they produce less power per sq ft, which is a bad thing on a boat. You want the most efficient use of your limited space.

Max then there are there are those of us that only need 100 watts to maintain our systems so I install lots of systems using 2 100 watt panels and a cheap 30 amp pwm controller ( I get the p30l programable pwm unit for $20 USD).

[john61ct]

Originally Posted by Mike OReilly

Funny you should ask. We are into our third crappy day of rain and little wind here. Batteries are really taking a beating. So yes, if we don’t get a good solar/wind boost today we’ll have to either run the engine (big diesel or small generator), or turn off the fridge.

And for bank longevity this would be done well before hitting 50% SoC.

Ideally in the morning, to a high enough SoC so that the solar will get the bank to 100% (not 95, not 98) Full.

A good battery SoC monitor really helps.

WRT controller innovation, more SCs with monitoring functionality built-in would be great.

Bogart SC-2030+Trimetric, WhizBang, any others out there?

[IOPSailor]

In a solar and wind gen set up, each using a separate controller... Solar producing 8 amps and wind producing 5 amps. And the batteries are accepting a charge. Will I get 13 amps? Or will I only get 8 amps because the solar is suppling the higher amperage?

[john61ct]

No Amps available are additive.

But the bank's SoC will determine what actually gets absorbed.

Ideally voltage transition setpoints and hold-absorb settings will match.

[IOPSailor]

Originally Posted by john61ct

No Amps available are additive.

But the bank's SoC will determine what actually gets absorbed.

Ideally voltage transition setpoints and hold-absorb settings will match.

Thanks. I'd been told the opposite so was considering a dual controller if I add a wind gen.

[Mike OReilly]

Originally Posted by IOPSailor

Thanks. I'd been told the opposite so was considering a dual controller if I add a wind gen.

Definitely additive. I tried running with the single controller last season running both solar and wind through it. Turned out not so great. The controller was designed to run the mill but also accepted solar. It operated with a simple voltage or amp cutoff. Not good for getting the batteries topped right up.

This season I installed a victron mppt for the solar. So far the results have been impressive.

[john61ct]

Yes I would love to hear of a quality controller that handled both wind and solar concurrently **well**.

I'm sure it would be costly, but just to know such a beast even exists would be useful.

[Mike OReilly]

Someone like Mainsail would know, but what I learned through last season's trial and tribulations is that wind is great for bulk charging, but not so great for absorption and float. Not sure if all windmill controllers are the same, but mine didn't manage the solar well.

BTW Ken, I did break down and run my little gasoline generator for a couple hours today. Cloud and rain for three days now, and the prospects for tomorrow are no better so it's Yamaha amps for now.

[Kenomac]

Originally Posted by Mike OReilly

Someone like Mainsail would know, but what I learned through last season's trial and tribulations is that wind is great for bulk charging, but not so great for absorption and float. Not sure if all windmill controllers are the same, but mine didn't manage the solar well.

BTW Ken, I did break down and run my little gasoline generator for a couple hours today. Cloud and rain for three days now, and the prospects for tomorrow are no better so it's Yamaha amps for now.

Well here's what I did to solve the same issue... Instead of remaining where I was with the weather looking even worse for tomorrow (rain and 30 knot winds), I pulled up the anchor and moved the boat to sunshine 29 miles away, to what has to be one of the nicest achorages I've ever been to.

Mike, come on over to Europe where we have winter followed by six months of glorious and continuous sunshine. Plus the food's better and the beer much cheaper.... and all of it's imported!

[Mike OReilly]

Originally Posted by Kenomac

...Mike, come on over to Europe where we have winter followed by six months of glorious and continuous sunshine. Plus the food's better and the beer much cheaper.... and all of it's imported!

Sounds wonderful, but where are the icebergs, brisk winds, zero crowds and long, deep fiords to explore? [emoji6]. We might get there some day. Who knows... Ireland looks interesting to me.

[LoudMusic]

Originally Posted by socaldmax

If you did that, you'd be wasting your time, money, and valuable space on your boat. Why waste time bolting down 3 100w panels when you can simply bolt down 1 300w panel?

As I tell customers, I don't even pick up the drill for panels smaller than 200w.

Based on the prices at my distributor, 100w panels cost $65 (65cents/watt), his 280w panels are the big bargain at $86 ea (30.7 cents/watt), the 230w panels are $72 (31.3 cents/watt) and the 320w panels come in 3rd at $119 ea (37.2 cents/watt.) Why pay more for less? Another nice side benefit is I can use a cheap 20A controller connected to each 320w or 280w panel and get 20A or close to it at peak summer hrs and not worry about series connected panel shading or even shading losses in parallel from the loss of MPPT efficiency. Large panel efficiency and one controller per panel gives max MPPT harvest.

Finally, the 100w panels are quite often less efficient than the 300w panels, so not only do they take up a lot more space, they produce less power per sq ft, which is a bad thing on a boat. You want the most efficient use of your limited space.

What if I didn't care that it costs more and was focused on getting the most possible power production at all times? Frankly the difference between $86 and $195 is irrelevant, if the $86 solution produces 0% of its capacity when the $195 solution produces 33% or 66% due to shading.

Also, if there is a failure in the system the production goes down in a smaller percentage.

The costs have gotten so low that I don't think discussing price is even worth the time. To me it's about getting as much reliable power production as possible into the space available.

[mitiempo]

Originally Posted by john61ct

Yes I would love to hear of a quality controller that handled both wind and solar concurrently **well**.

I'm sure it would be costly, but just to know such a beast even exists would be useful.

It does exist.

MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels

[socaldmax]

Originally Posted by LoudMusic

What if I didn't care that it costs more and was focused on getting the most possible power production at all times? Frankly the difference between $86 and $195 is irrelevant, if the $86 solution produces 0% of its capacity when the $195 solution produces 33% or 66% due to shading.

Also, if there is a failure in the system the production goes down in a smaller percentage.

The costs have gotten so low that I don't think discussing price is even worth the time. To me it's about getting as much reliable power production as possible into the space available.

You have free will, you can install whatever you want. However, installing any panels where you know it's going to get shaded is pretty much a waste of time, money and energy, regardless of size. I'm not going to bother with every possible scenario in terms of size of shade, percentage of 300w panel vs percentage of 3 100w panels shaded, etc.

The first rule of installing panels is to not mount them in shade. Since one only gets power from unshaded panels, I still feel that it's more advantageous to install a larger, more efficient panel.

In the event of panel failure, yes, if you only have a single 300w panel and it fails, you're down to zero power, but in that case you're going to replace it as soon as possible, so it's only a temp. setback.

The final answer is don't install any panels in a shaded area.

[john61ct]

Originally Posted by mitiempo

It does exist.

MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels

Nice, thanks, love the WBjr combo idea.

[LoudMusic]

Originally Posted by socaldmax

You have free will, you can install whatever you want. However, installing any panels where you know it's going to get shaded is pretty much a waste of time, money and energy, regardless of size. I'm not going to bother with every possible scenario in terms of size of shade, percentage of 300w panel vs percentage of 3 100w panels shaded, etc.

The first rule of installing panels is to not mount them in shade. Since one only gets power from unshaded panels, I still feel that it's more advantageous to install a larger, more efficient panel.

In the event of panel failure, yes, if you only have a single 300w panel and it fails, you're down to zero power, but in that case you're going to replace it as soon as possible, so it's only a temp. setback.

The final answer is don't install any panels in a shaded area.

Well that I can agree with

But it's a sailboat, so some shading is inevitable.