Any experts on solar to provide an update of things.

Kermit · Jul 8, 2014

I have a 5-watt solid panel connected directly to each of my 2 batteries. Keeps them charged quite nicely. I attach them with alligator clips and put them on the sliding hatch during the week and stow them while sailing.

Maine Sail · Jul 8, 2014

jbinbi said:
I have searched but not found anything new on solar panels and systems for charging, yet there has been lots of new developments in panels and pricing in the last few years.

I am wondering if there are any experts on this forum that would provide a tutorial update on say if it is worth it to use the new inexpensive roll up panels for trickle charging during the week, what type of panels give the most bang for the buck for installed panels, when you need what type of charger etc.

Would be lots of work to get a great tutorial done and I would think these things are best done during the winter when you are not enjoying being on the water, but it would be fantastic information that I bet lots of us would really benefit from.

So anyone who can contribute, even piece meal, it would be much appreciated!

Installing A Small Marine Solar System

Joe · Jul 8, 2014

jbinbi said:
I will hold my tongue. As I stated, I did search. I have lots of links that are old. i have found nothing new. I said a tutorial would be great, I do this for people in my field, I said I realize it is as labor of love and also said anything piecemeal would be great as well.

As a EE myself, the best advice I can give you is that you are charging too little for your time. Forums are for sharing advice.

You're good in my book... good topic... carry on.

trainmanjess · Jul 8, 2014

hello all

I have 2 - 30 watt solar panels and a controller on my Kittiwake 23 sailboat... it keeps my battery bank (2) fully charged at all times... it also allows me to use lights, radio, and fridge during the day without depleating my battery bank...

on my Morgan 35' sailboat, have 2 - 120 watt solar panels and a controller... this keeps my battery bank (4) fully charged and allows me to use a lot of electricity during the day if needed, and at night I go into concervatude mode but still have enough electricity...

I have been looking at wind generators... I found this type from japan that the blades are all vertical (straight up)... it is suppose to be much more efficient that the propeller types...

sincerely
Jess

CharlzO · Jul 8, 2014

Just from what I've pieced together myself, comes as follows...

The first thing to consider, is usage. How large is your house bank, how much do you anticipate using and for how long. For example, if it's a weekender boat, how much do you think you'll draw off the bank that will need to be replenished. If you are using 20 amps, and you only need to charge that over a 5 day stretch before the next trip, it will mean a small enough panel to do so.

To go along with that, how do you anticipate the panel's usage? Will it be used during the entire week / off-sailing time to top off the batteries, or will you only be able to hook it up for a particular time or day(s)? That will obviously go along with determining the size of the panel.

Without knowing those, it's difficult to say the best options. If memory serves, the flexible panels aren't quite as efficient as a rigid, but are getting up there and are a very popular option, especially if the mounting options are more limited.

Maine Sail's tutorial is much better for the details than I could explain, and well worth the read. There are countless options and models out there, and many are paired as a kit with a charger as well.

I have an inexpensive Renogy Solar 100w kit which came with a controller, and is mounted on the stern rail. It definitely is more than enough for what I currently use. It might not be the most efficient, but the price makes it a very good value (to me, other people may not see it the same, and that's ok too). Plus, it also gives my electronics room to grow. I currently run a chartplotter and VHF full-time while cruising, a 12v phone charger part time, and have just recently added a 24" LED smart TV that is supposed to be relatively low-draw set paired with a small inverter to run it. I sail every weekend, the TV has only been used one night so far as I just got it on Friday night, and the solar has no problems topping the batteries off within a few hours of good sunlight.

It all comes down to the current and/or expected usage, I suppose.

Chief RA · Jul 9, 2014

Sorry jbinbi, and other members. Chief

Bill Roosa · Jul 9, 2014

Well to do any real evaluation YOU need to do the standard electrical production-storage-usage drill. Start with usage and define ALL your loads while on battery power, how long/often/duration that load will be..... and convert them into Ah. Any place you can lower the loads is money well spent. Also look at "producing while you consume" opportunities. For instance I use a holding plate for the reefer and freezer and only run the units when the sun is shining (and the solar are producing). this helps avoid the losses from storing (in and out) the energy in the batteries. Once you have the loads reduced as much as practical you can begin to balance the production-storage side of the energy budget. Start with what you have storage wise and see how much/often production will be needed to meet your "worst case" sailing pattern. a couple of lessons learned, there is no wind in that snug harbor completely protected from the wind, the solar does not work so hot either as there are lots of trees to shade the panels till late morning and they they show up again in early afternoon.
I believe the spreadsheet that does a lot of the heavy lifting is still in the archives somewhere but have not been there lately to check. If you need a copy email me and I'll shoot one out to you.

Bill Roosa · Jul 9, 2014

and on a related note, would there be interest in a pole mounted solar panel that automajicaly tracks the sun. I'm working on one with about 144 watts (12 amps) that will track the sun when it is up and then safe itself during darkness. This would (I'm hoping) also work while sailing and healing-tacking but I don't know if the motors I'm using are up to slew rates that high. also don't know the energy consumed in that mode and wither it would be worth it. I do know that it is worth it, energy wise, when you are at anchor as my back of the envelope calculations show a 45-50 increase in collection over a flat panel.

justsomeguy · Jul 9, 2014

Bill Roosa said:
and on a related note, would there be interest in a pole mounted solar panel that automajicaly tracks the sun. I'm working on one with about 144 watts (12 amps) that will track the sun when it is up and then safe itself during darkness. This would (I'm hoping) also work while sailing and healing-tacking but I don't know if the motors I'm using are up to slew rates that high. also don't know the energy consumed in that mode and wither it would be worth it. I do know that it is worth it, energy wise, when you are at anchor as my back of the envelope calculations show a 45-50 increase in collection over a flat panel.

I'd like to see your prototype(s) when you get around to it.

trainmanjess · Jul 9, 2014

hello all

Bill - I would like to see it when you have it finished... I am very interested in it too

sincerely
Jess

seadaddler · Jul 9, 2014

Solar stik

They do make a solar stick on a pole that does what you are trying to do but not auto no $$$$ motors but does easy turn and fold at angles by hand.
Java had one installed to his 356 stern so maybe he will jump in.
Nick

Bill Roosa · Jul 9, 2014

seadaddler
that was my initial motivation. and that flat mounted panels are a serious, but practical, limitation.
But I don't want to hyjack the thread so if youall have any interest just email me on the site

Maine Sail · Jul 9, 2014

Bill Roosa said:
and on a related note, would there be interest in a pole mounted solar panel that automajicaly tracks the sun. I'm working on one with about 144 watts (12 amps) that will track the sun when it is up and then safe itself during darkness. This would (I'm hoping) also work while sailing and healing-tacking but I don't know if the motors I'm using are up to slew rates that high. also don't know the energy consumed in that mode and wither it would be worth it. I do know that it is worth it, energy wise, when you are at anchor as my back of the envelope calculations show a 45-50 increase in collection over a flat panel.

Bill,

If your back of the napkin formulas can prove to beat the results below by 45-50% please bring it!!:dance:I would love to see 68Ah's out of a 140W panel in Maine!!

Seems that this would be exceeding reality but I am always open to be proven wrong..

This test was a direct head to head I did for a solar company. Both panels were identical Kyocera 140W polycrystalline laid perfectly flat in an area with no shade, like they would be on a boat..

Each panel was placed flat & side by side the other and both got as identical treatment from mother nature. All wires to and from controller were identical length gauge and all terminated with the identical tools to aircraft specification. To eliminate any discrepancies the panels were swapped to their respective controllers each morning.

Data capturing was cleared and re-set each morning and screen captures were used to document progress. This testing was conducted over a week in early May 2014 in Maine. Each day's performance was different due to weather but the flat panels produced quite remarkable results and the MPPT handily beat the pants off PWM each day. On this day it was a 19.6% gain over PWM by 5:23 PM.

Identical 140W Kyocera Panels - Only Difference Is The Controller

MPPT = 45.12 Ah's by 5:23 PM
PWM = 37.73 Ah's by 5:23 PM

AD1 = Battery Terminal Voltage
AD7: AMPS 1 = Genasun MPPT Controller
AD8: AMPS 2 = Morninstart ProStar 15 PWM Controller
AD13: Cumulative Daily Ah's Returned To Bank (Genasun MPPT)
AD14: Cumulative Daily Ah's Returned To Bank (Morningstar PWM)

Battery Bank = 400Ah LiFePO4

Bill Roosa · Jul 9, 2014

Well MS I would note that at dawn and dusk the angle of the panel to the sun is 0. At local noon it is 90-latitude or 50is for most of us in the US.
The "angle factor" is the cosine(pane-sun angle) so.....
at dawn and dusk
cos(90-0)= 0 That would be 0*the max panel output.
at local noon cos(90-lat)= cos(90-40)=.64
That would mean that at the best case the max you will get at latitude 40 degrees is 64% panel output. At all other times the output would be even less.
64% is 45% less than 100% so I would make the assertion that (at 40 degrees latitude) you could get an immediate 45% improvement at lest by aiming the pane at the sun so the sun-panel angel is 90 degrees all the time. If you do the intigration over an entire day of sun-panel angles you get anywhere from 45-65% improvement depending on the time of year.
It has nothing to do with the panel size or the type of charge controller is has to do with capturing more sun.

Bill Roosa · Jul 9, 2014

and if you want to test this just glue a toothpick to the panel edge and tilt the panel till the toothpick shadow disappears. The compare the outputs between flat on the ground and aimed at the sun.
The solar stick guy demonstrated this when I met him at the Pentagon technology day. It is pretty dramatic!

Maine Sail · Jul 10, 2014

Bill Roosa said:
If you do the intigration over an entire day of sun-panel angles you get anywhere from 45-65% improvement depending on the time of year.
It has nothing to do with the panel size or the type of charge controller is has to do with capturing more sun.

But we can't forget temperature of the panel. It does play a huge roll, especially with MPPT controllers. Angling at the sun will yield a hotter panel so those temp increases would need to be factored in, which is extremely difficult to track. With cool panels I can easily see the 30% gains the MPPT makers claim, but as the panels heat up the average gains I see up were are 15% - 20%..

We also can't forget the tracking motors and their consumption and anchored and moored boats move constantly. In order to make this a reliable product in the marine environment will make it very, very costly to sell to the end user.

I know Brian & Steph of Solar Stik and have talked with them about automated tracking on numerous occasions. They would do it if it could be a worthwhile venture but the tracking chews into efficiencies and gets extremely costly to make "marine proof".... The product would be extremely expensive to both make and sell into the marine market...

I have Solar Stiks out there on cruising boats. It is expensive, but very robust and extremely well executed. The limitation is the 100W and owner forgetfulness. I have one customer who routinely forgets to lay his panels back flat when he leaves the boat and this KILLS his 100W performance while on the mooring. Brian and Steph have apparently moved to land based markets, including military applications, because the marine market apparently can't drive the business alone.

Last week I installed 250W of solar on a bimini for less than 1/4 of what it would cost to do a Solar Stik with 100W. No matter how much the owner moves the Solar Stik he won't beat the two 250W flat mounted panels. Everything is a compromise and, in general, boaters want the most bang for the buck. More flat mounted panels will cost less.....

This is no diffent than MPPT vs. PWM. More watts will cost less than going to MPPT. When you run out of real estate then MPPT makes more sense unless you need the programing features of an MPPT that is not often avaible in a PWM..

As I said, I would LOVE to see this work but it must be ROBUST, RELIABLE, CORROSION RESISTANT, LIGHTWEIGHT and able to withstand storms at sea and winds over 60 knots. If you can do that at a price where you can makes some money and you actually sell some then BRING IT ON!!! I will probably be your biggest customer....

Bill Roosa · Jul 10, 2014

I would agree that if you collect more sun you are going to get a hotter panel. That does not dramatically change the rather large (45%) increase in output you get from aiming at the sun all day though.

Maine Sail · Jul 10, 2014

Bill Roosa said:
I would agree that if you collect more sun you are going to get a hotter panel. That does not dramatically change the rather large (45%) increase in output you get from aiming at the sun all day though.

I really don't know how you quantify that without actually measuring and tracking the temps and outputs of flat vs. aimed panels? We know only what sun angles do, not what the temp increases may alter.

Take for example the Kyocera 140W panel which I install a boat load of. This panel only has a Pmax of 140W at 25C/77F. At 45C/113F Pmax quickly turns it into a 101W panel.

Ipmax goes from 7.91A at 77F to 6.33A at 113F.. As panel temp go up these numbers drop more.. We are lucky on boats to have more air cooling than on roofs but I still see an measure panels from 110F to over 130F...