Wind generator and Solar Panels

[skipgundlach]

Originally Posted by mcarling

Assuming we're talking about a 12V system, 100AH per day is 1200 watt-hours per day. N=1200. 1200 / 2 = 600 watts minimum solar capacity (my recommendation). 2 * 1200 = 2400 watt-hours (or 200AH) minimum LiFePO4 battery capacity (again, my recommendation). Minimum means the minimum I recommend. More is better; less might work fine. Others will be more or less conservative than I am and have different opinions.

Because we already have wind and solar installed, I generally can't be very assured of my actual consumption. However, in calm, dark conditions, with most everything (ghost loads = ~1.7A) other than the refrigerator off, we frequently will average 7A (meaning, if it were 10 hours, 70AH deficit in that time) overnight, or over 160AH would not be uncommon.

We felt privileged to be able to install 4 L16 batteries aboard. I consider that a reasonable level (currently 740AH @20 hours, previous were 880AH).

We rarely let our bank go below 1/3 depleted before firing up the Honda. That happens entirely too often for the Admiral's taste, and my wallet. Our 370W solar is 10 years old; I'm trying to find two mega (~300W or better) panels which will not exceed 42" wide, length unimportant, with ~20% efficiency, to replace those.

We have a HF whip and a KISS wind which, depending on orientation, may shadow somewhat, but even our oldy-moldy panels routinely put out over 10A in cloudy conditions, and 20A isn't uncommon, though it requires our being as far south as possible in the Bahamas.

The KISS continues to do its work; this morning we are in a weather event where it's very up/down, but we're getting 10A most of the time, and, as happened during Friday's weather event, we're pegging our analog ammeter at over 30A fairly frequently. Friday was more consistent, so we had the thermo-cutout phenomenon a couple of times, but on the whole, it just kept on pumping in the amps while the solar was at zero.

That said, anybody got a reference for 300+W solar under 42" wide, that can ship two panels to Vero Beach (one I thought I had nailed only sells pallet load lots)?

Thanks.

[rabbi]

I like water gens, but for the limited usage they get those gens are pretty expensive. Maybe there are cheaper options but the cheapest I found start at 2500 Euro, most are around 3500 Euro


We run one engine for an hour or so on each night passage. 3500 Euro equals the diesel and cost of engine wear&tear associated with maybe 1500-2000 passage nights.


I wonder why there is no "add on" kit to convert existing saildrives into a water gen. With fixed blade props it is free-spinning anyway.

[Maine Sail]

Originally Posted by patprice

My Aussie boat, with the AIR-X only has about 200 AH for house use.
The problem is, the regulator in the AIR-X checks at short time intervals the voltage at the batteries. Being low on AH's the voltage goes up quickly though the batteries are not full. The AIR-X thinks they are and stops charging. Soon after it checks again and the voltage is down. So it starts charging again.
Stop start...stop start...stop start.... sheesh.

Pat
PS I prefer solar.

Wind gens use shunting or on/off regulation. If the batts are quickly hitting the OFF voltage yet they are actually depleted then the batteries are likely sulfated.

[Maine Sail]

Originally Posted by thomwessels

I've had solar + wind gen on my boats for 40 years. No question solar is necessary (and getting cheaper (WINNING!!).
Wind gen is the other necessity. Why not exploit the very thing that we NEED?

What wind gen and solar panels were you using in 1976?

[monte]

Originally Posted by Maine Sail

Wind gens use shunting or on/off regulation. If the batts are quickly hitting the OFF voltage yet they are actually depleted then the batteries are likely sulfated.

Our air X had a little potentiometer? screw on the side to adjust voltage point I think

[Maine Sail]

Originally Posted by monte

Our air X had a little potentiometer? screw on the side to adjust voltage point I think

Yes most have an adjustable OFF / brake/dump voltage and some even have an adjustable ON / cut-in voltage. Wind gen controllers generally work by bringing the batteries to a pre-set voltage limit of say 14.2V then shutting off and letting the battery voltage decay back to a cut-in voltage point. During this off period the wind gen is braked or dumped to a dummy load to slow the blades or stop them entirely.

Once at target voltage, lets call it 14.2V, they either shunt the current to a dump load or short the winding's to brake the rotor.

Once battery voltage has decayed to say 13.2V they turn on again, bring the battery back to 14.2V and shut off..

14.2V OFF > VOLTAGE DECAYS > 13.2V ON > VOLTAGE INCREASES > 14.2V OFF > VOLTAGE DECAYS > 13.2V ON > VOLTAGE INCREASES etc. etc...

Unlike a solar panel or alternator we can't simply PWM a wind gen to a regulated voltage limit or the blades will be RIPPING and the unit can wear prematurely. With a wind gen we need to stop or brake the blades when there is little current demand and this is done via shunt or simple ON/OFF regulation.. Wind gens are great for bulk charging but a pretty poor source for absorption where we want to see a voltage held steady.

[REsCat]

Does anyone have any realtime experience with articulating solar panels/arrays and possible worthwhile benefits gained from doing this?
I talked with some dealers at the boatshows and they generally felt the benefits were minimal for the added complexity and expense and that mounting them flat and away from shading sources was the best approach.

Bob

[monte]

Well I looked at my battery monitor yesterday at around 3pm and wondered why I wasn't seeing the same 50Ah going in from the panels I saw an hour earlier. It was down to around 10Ah. A quick look at the panels showed the sun was down to about a 20 degree angle. 1200W of panels in clear Caribbean skies. If they were tiltable I guess I could have packed in another 60Ah before sunset. Ok some quick guesstimate math.... Flat panels work pretty well from 1000-1500, so 5 hrs X 40Ah = 200Ah/day. If they were tiltable we might increase that to 8 X 40Ah so 320Ah/day. Around a 50% increase. Or 1200Ah flat panels equates to 800Ah tilting panels ( if you could be bothered tilting them ) Shading probably comes into the equation a bit as well, it's likely morning sun would have a lot of rigging shade on tiltable panels so the increase is likely to be closer to 30%
Just guessyguessy figures so don't shoot me.

[REsCat]

Thanks for that Monte, I guess one key operative factor as you have pointed out is being dedicated to tilt them on a frequent basis to try and gain that optimum angle and does it become a nuisance distraction from other things you are or should be doing?

Bob

[StuM]

Originally Posted by monte

Well I looked at my battery monitor yesterday at around 3pm and wondered why I wasn't seeing the same 50Ah going in from the panels I saw an hour earlier. It was down to around 10Ah.

Maybe because you were at a higher SOC and the batteries were not absorbing at the higher rate?

A quick look at the panels showed the sun was down to about a 20 degree angle.

1200W of panels in clear Caribbean skies.

In the Caribbean, basic geography and mathematics says that the 80% reduction in output wasn't because of lower sun angle.

For horizontal panels, insolation is roughly proportional to the sine of the sun's elevation. ("roughly" because of the attenuation by the increased thickness of atmosphere that the radiation has to pass through at lower elevations)

Even at the very north of the Caribbean at 22°N today, the sun is over 30° at 3pm. At 2pm, it is at just over 40°. At peak it is at 47°

That would be giving you the following percentages of maximum (sun overhead) output
Noon: 47° 74%
2pm: 40° 64%
3pm 30° 50%

So at 3pm you would be getting 78% of what you were getting at 2pm

In the middle of the Caribbean at 15°N, the figures are better:

Noon: 54° 80%
2pm: 47° 74%
3pm 37° 60%

So at 3pm you would be getting 81% of what you were getting at 2pm

If they were tiltable I guess I could have packed in another 60Ah before sunset. Ok some quick guesstimate math.... Flat panels work pretty well from 1000-1500, so 5 hrs X 40Ah = 200Ah/day. If they were tiltable we might increase that to 8 X 40Ah so 320Ah/day. Around a 50% increase. Or 1200Ah flat panels equates to 800Ah tilting panels ( if you could be bothered tilting them ) Shading probably comes into the equation a bit as well, it's likely morning sun would have a lot of rigging shade on tiltable panels so the increase is likely to be closer to 30%
Just guessyguessy figures so don't shoot me.

1200W @14.4V = 83A
I will assume the worst case and that you are at 22°N.
That means the best you could expect would be:

83 *.74 = 61A at noon
83 * .64 = 53A at 2pm
83 * .5 = 41.5A at 3pm

So the drop to 10A wasn't because of the sun/panel angle, I'd guess that your batteries were fairly full by then and only accepting 10 of the available 40A (or maybe you had some heavy loads drawing power)

While tilting panels will give you some gain, it will be nowhere near 30%

(I suppose I could knock up a spreadsheet to calculate it but I can't really be bothered, too many variables throughout the year)

[smj]

Originally Posted by skipgundlach

Because we already have wind and solar installed, I generally can't be very assured of my actual consumption. However, in calm, dark conditions, with most everything (ghost loads = ~1.7A) other than the refrigerator off, we frequently will average 7A (meaning, if it were 10 hours, 70AH deficit in that time) overnight, or over 160AH would not be uncommon.



We felt privileged to be able to install 4 L16 batteries aboard. I consider that a reasonable level (currently 740AH @20 hours, previous were 880AH).



We rarely let our bank go below 1/3 depleted before firing up the Honda. That happens entirely too often for the Admiral's taste, and my wallet. Our 370W solar is 10 years old; I'm trying to find two mega (~300W or better) panels which will not exceed 42" wide, length unimportant, with ~20% efficiency, to replace those.



We have a HF whip and a KISS wind which, depending on orientation, may shadow somewhat, but even our oldy-moldy panels routinely put out over 10A in cloudy conditions, and 20A isn't uncommon, though it requires our being as far south as possible in the Bahamas.



The KISS continues to do its work; this morning we are in a weather event where it's very up/down, but we're getting 10A most of the time, and, as happened during Friday's weather event, we're pegging our analog ammeter at over 30A fairly frequently. Friday was more consistent, so we had the thermo-cutout phenomenon a couple of times, but on the whole, it just kept on pumping in the amps while the solar was at zero.



That said, anybody got a reference for 300+W solar under 42" wide, that can ship two panels to Vero Beach (one I thought I had nailed only sells pallet load lots)?



Thanks.

I've got a friend in the Keys that deals with Sunpower solar panels. I believe the 400 and 425 watt panels are just under 42" wide. Send me a pm and I will send you his contact info.


Sent from my iPad using Cruisers Sailing Forum

[skipgundlach]

Originally Posted by smj

I've got a friend in the Keys that deals with Sunpower solar panels. I believe the 400 and 425 watt panels are just under 42" wide. Send me a pm and I will send you his contact info.


Sent from my iPad using Cruisers Sailing Forum

skipgundlach@gmail.com, and thanks!

[mcarling]

Originally Posted by REsCat

Does anyone have any realtime experience with articulating solar panels/arrays and possible worthwhile benefits gained from doing this?

I've thought about tilting panels a lot and made various calculations in the context of a solar powered boat, such as Sun21 or Planet Solar. In my opinion, tilting panels are not worth the trouble.

[rabbi]

Originally Posted by mcarling

I've thought about tilting panels a lot and made various calculations in the context of a solar powered boat, such as Sun21 or Planet Solar. In my opinion, tilting panels are not worth the trouble.

If one has space left I think its easier and often cheaper to use that space for additional panels instead of inventing some often flimsy or costly tilting mechanism.

I had a tilting mechnism in mylast boat and frankly never used it much. At the end I don't consider adjusting solar panels that much fun compared to say having a drink, playing with the kids on the beach, snorkeling, etc.

[skipgundlach]

Originally Posted by smj

I've got a friend in the Keys that deals with Sunpower solar panels. I believe the 400 and 425 watt panels are just under 42" wide. Send me a pm and I will send you his contact info.


Sent from my iPad using Cruisers Sailing Forum

BTW I went looking; their 400/425W panels do not claim salt test; their 300 series does...

Thanks for the lead; inquiry out to a Vero supplier, too, JIC.