Solar Panel Mounting on Bimini

[tartansail]

Originally Posted by noelex 77

The voltage increase is not normally needed. Even under low light solar panels will still produce lots of volts just no amps. It is possible sometimes when some cells are under shade to get more power by boosting voltage, but in practice the panels will be all be at different voltages.

So voltage boosting is only used under very specific circumstances such as tring to use a 12v panel in a 24v system.

Solbian have manged to produce some very efficient panels. It's cheaper (and possibly more efficient) for them to use the same cell in different panel sizes. This means the smaller panels have fewer large cells instead of the conventional approach of leaving the number of cells constant and decreasing the size of the cells for a smaller panel.
Because the small panels have fewer than 36cells the voltage needs to be boosted. There are very few solar controllers that will do this. Gensun make one of these.

The effeciency loss in the controler in boosting the voltage needs to be traded against the improved effeciency of the panel. They can, if enough panels are available be hooked up in series, but this does introduce some new advantages and drawbacks.
The low voltage panels with a controller boosting the voltage are a new and insteresting development I have not personally used them and it would need some controlled tests to match the output against "conventional panels". At the end of day features like light weight and flexibility are probably more important than a small difference in effeciency.
They are unfortunatly very expensive at the moment.

The only caution I would suggest is if using a low voltage panel that the output may be a bit less once the voltage boosting has taken place.

If using conventional voltage panels the parasitic losses of driving a controller that will boost voltage are likely to outweigh the rare occasions where the voltage boost is helpful.

Many thanks! I appreciate your knowledge and your straightforward responses.

Once the weather warms up, I'll have an opportunity to give some feedback on the Solbian panels and the Genasun controllers. I agree with you that the panels are pricey. However, for installations like mine -- 2 X 125 watts on the bimini -- the price difference starts to shrink if you include the costs of the frame and, in some situations, modifications to the bimini itself. The opportunity costs when the admiral made her opinion known about the extra framing eliminated any residual cost difference.

[CAELESTIS]

Originally Posted by noelex 77

The Sunpower panels are some of the most efficient, but they are unusual. They active some of this efficiency by polarising the surface of the solar cells. To do this they require a positive grounding system which is not practical on a yacht. The sun power information is here:
http://www.ftp.tognews.com/GoogleFil...owerPanels.pdf
There was some discussion on CF here about this:

http://www.cruisersforum.com/forums/...ing-90082.html

These are the only panels that do this. So having said its very simple, I guess there are some traps.

Sun power do make some slightly less efficient panels that are suitable for negative grounding.
There is a representative that has posted on CF who will be able advise you much better on what sunpower panels need possitive grounding.

If you get the sunpower panels that do not require positive grounding your plan sounds great.

The data sheet says they DO NOT require positive grounding.http://www.sunpowercorp.co.uk/cs/Sat...&ssbinary=true

Noelex, would the E19 245w panel work for a 24v house bank with a MPPT controller? For the same footprint these would produce 20w/panel more than the Sanyo.

[familycruisers]

I'm getting 2 of these. http://www.motechsolar.com/en/doc/mo...lear3BB_A4.pdf
Any opinions on the motechs?

[noelex 77]

Originally Posted by CAELESTIS

The data sheet says they DO NOT require positive grounding

It is confusing. I believe there are 2 different types of sunpower panels. Some require the positive grounding and others do not.
Unfortunatly the big market is for terrestrial , manly domestic, instalations. Panel manufactures want to keep their installers happy and are sometimes reticent to release basic information that would help amateurs tring to install these panels themselves. They see these panels as only being suitable for professional installation, which is reasonable for large, high voltage array hooked up to grid system, but not the smaller systems we use.

Originally Posted by CAELESTIS

Noelex, would the E19 245w panel work for a 24v house bank with a MPPT controller? For the same footprint these would produce 20w/panel more than the Sanyo.

Yes if the panel will not loose effeciency with negative grounding the voltages etc of the above panel are fine.

[Pelagic]

Searching for “Positive Ground” answers for the Sunpower E20/350 watt, turns out Steve Dashew installed same panels with some ingenious solutions.
SetSail» Blog Archive » Sunpower 320 Solar Panels – Real World Output Data

My problem with Sunpower, is that there are no Retail Partners-Installers in the Philippines and Sunpower will only deal and supply technical answers thru them.

Anyone know a Sunpower Installer who will help a boat owner?

[Pelagic]

Perhaps some of you have already investigated pros and cons of using micro-invertors on a marine installation to isolate individual panels from shading deficiency.

Does this work the same as a MPPT, but installed on each panel?

Micro-Inverters vs. Central Inverters - Energy Informative

[familycruisers]

Work well in grid tie applications. Guess you could then run a charger.

[noelex 77]

Originally Posted by Pelagic

Perhaps some of you have already investigated pros and cons of using micro-invertors on a marine installation to isolate individual panels from shading deficiency.

Does this work the same as a MPPT, but installed on each panel?

Micro-Inverters vs. Central Inverters - Energy Informative

The link is mainly discussing individual inverters for each solar panel. This would not be advantageous on our systems, although there is some discussion of individual MPPT converters which is more applicable.
The concepts and practices from large domestic arrays are not often directly transferable to our much smaller DC based marine solar systems. One problem boat owners face is much of the advice and equipment is designed for these very different domestic systems.

The concept of individual MPPT regulators for each panel is an attractive one. The problem is finding an efficient, accurate tracking, MPPT regulator with low consumption. There were some designs that were developed primarily for the solar car races that may have worked efficiently. They were only available in semi finished form from small back yard companies and sadly they seem no longer available.
The closest commercial regulators are made by Gensun, but my reading of the scant technical information they provide would suggest that this approach would not provide an advantage at present, but this is little more than an educated guess.

[Pelagic]

Thanks Nolex… out of curiosity, what are your thought on the Dashew solution for using the Sunpower E-20 positive ground panels?

http://setsail.com/sunpower-320-sola...d-output-data/

[noelex 77]

Originally Posted by Pelagic

Thanks Nolex… out of curiosity, what are your thought on the Dashew solution for using the Sunpower E-20 positive ground panels?

SetSail» Blog Archive » Sunpower 320 Solar Panels – Real World Output Data

Almost everything the Dashews do is sensible with wonderful, practical engineering. However there are a lot of difficulties electrically isolating systems long term. It can be done, but I don't see it's worth the trouble for the small gain.
Suggesting the Dashews could have done better is a bit like saying God could have made a better world, but if it was me I would have utilised the large spaces such as the Bimini and top deck. I think this would have given a greater output and been less obtrusive.
Only recently has the cost and efficiency of solar, wind and battery reached the stage where it is practical for large boats with high demand electrical systems to consider solar and wind as alternatives to generator output.

A sligly simpler FPB with no generator a large solar array and a couple of D400 wind generators on the back would make a great cruising boat. Make mine a 64 footer, I am not greedy.

[Sumner]

I mentioned this at the beginning of this thread, but if I knew I was going to get substantial shading on one of the panels at times I'd go with something like Blue Sky's IPN-Remote...

http://www.blueskyenergyinc.com/uplo..._datasheet.pdf

....which draws between .25 and 1 watt and then two of their MPPT controllers. The 2512 if the amp load is less than 20-25 amps....

http://www.blueskyenergyinc.com/uplo..._datasheet.pdf

...or the larger 3024. They both have a .3 to 1 watt power consumption. I would think other manufactures probably have something similar.

Since the efficiency of a MPPT controller can be compromised by panels with different voltage I'd think the same would be true if one panel is shaded. With the two controllers both panels would be independently working at their highest efficiency and not be compromised,

Sum

[noelex 77]

Installing two MPPT to control the panels on a boat has some merit. Often port and starboard sides of the boat experience different conditions. Two controllers allows the separate tracking of Vmp.

It does have drawbacks, however. Good solar tracking requires expensive circuitry the top level controllers do this much better than the mid level controllers. It also requires considerable power and two good units can provide a significant drain in self consumption.
Many manufacturers are very sneaky with self consumption information. They quote power consumption of the controllers when in sleep mode, not actively tracking. Those controllers with low power consumption when tracking are often tracking very poorly.
Some "MPPT" simply pause and measure Voc. They then set the Vmp a set number of volts below this (say 3v). This leads to low self consumption, but poor tracking.

There are some controllers with reasonably low consumption and reasonably good tracking, but they are rare. Comparing two of these controllers with a single better controller has not been properly done. The results on average I suspect would be reasonably similar.

Two controllers provide redundancy, but two units does double the risk failure if each cannot handle the full output of the panels. A single controller will often provide better information such as AHrs in etc.
My preferred approach is a single good controller, but there is little objective data to sure this is correct.

[mausgras]

Has anyone thought of, or tried the new flexible panels. They can be simply laid out on the deck when at Anchor then folded up and put away when under sail. You could even tie them together in a raft with some floating noodles and put them on the water.

[Sumner]

Originally Posted by noelex 77

Installing two MPPT to control the panels on a boat has some merit. Often port and starboard sides of the boat experience different conditions. Two controllers allows the separate tracking of Vmp.

It does have drawbacks, however. Good solar tracking requires expensive circuitry the top level controllers do this much better than the mid level controllers. It also requires considerable power and two good units can provide a significant drain in self consumption.
Many manufacturers are very sneaky with self consumption information. They quote power consumption of the controllers when in sleep mode, not actively tracking. Those controllers with low power consumption when tracking are often tracking very poorly.
Some "MPPT" simply pause and measure Voc. They then set the Vmp a set number of volts below this (say 3v). This leads to low self consumption, but poor tracking.

There are some controllers with reasonably low consumption and reasonably good tracking, but they are rare. Comparing two of these controllers with a single better controller has not been properly done. The results on average I suspect would be reasonably similar.

Two controllers provide redundancy, but two units does double the risk failure if each cannot handle the full output of the panels. A single controller will often provide better information such as AHrs in etc.
My preferred approach is a single good controller, but there is little objective data to sure this is correct.

Those are definitly some points to consider and check into with whatever components you are thinking of buying. According to the specs on the Blue Sky controllers it looks like the 2512 (good for 20 to 25 amps depending on panel type) consumes ..

0.30W typical standby 􀁴 1.0W typical charge ON

...that isn't much and the IPN ProRemote ....

Receives communication and power from charge controller via
standard 4-pin telephone cable

...

0.25W Typical • 1.0W Typical with backlight on

... there again not much so worst case is about 3 watts for the two controllers and the remote. The remote...



...also can control the controllers (up to 8) to a greater degree vs. running the controllers in a standalone condition like we are doing. It monitors the total amp usage in and out.

I'm not saying the the Blue Sky controllers are the best or the only ones to consider, but they are recommended by a number of solar sites as ones to consider. I feel in a situation where you know you are going to have shading like the PO is then consider 2 controllers. Don't we go on and on about how much shading will effect the output of an array? You would still get some output from the shaded one and full available output from the one in the sun. I'll bet what this makes up with greater efficiency on the panel in the sun will far offset a couple watts power to run the extra controller and the ProRemote. This was the recommendation to me from a Blue Sky tech rep and makes sense.

If one thinks another brand of controller is better then go for it as you will still get the benefits as long as the controllers can work together.

The chance of having a controller going bad does go up with two, but with two controllers you still have some output vs. one controller and having it go bad. If you spent the extra then one controller could still handle the whole array. In our situation we only run one as we have no substantial shading and the 3024 can handle our 480 watts. If we did have shading and ran two controllers (2 2512's) I'd just run half the array off the working controller and order another one. If we were crossing oceans or going to places where you can't easily obtain replacements then I'd size the controllers so one or the other could handle the whole array.

Lots of options, a number of which will work, just my thoughts and some of this depends on how close you are running the array to the limits of the array. On our Mac with 200 watts the array just barely makes what we need so maybe looking for the very best possible controller makes sense. With the Endeavour and 480 watts we are way over what we need so can afford a less efficient array. Still I'm happy with what the controllers are doing,

Sum

[Pelagic]

Originally Posted by CAELESTIS

The data sheet says they DO NOT require positive grounding.http://www.sunpowercorp.co.uk/cs/Sat...&ssbinary=true

Noelex, would the E19 245w panel work for a 24v house bank with a MPPT controller? For the same footprint these would produce 20w/panel more than the Sanyo.

On the Positive Ground issue, I found this bit of information.

If I can confirm the power rating for the E20 327 with negative ground, that will simplify my decision.


… for 98% of the people that use Grid Tied solar--Positive grounding is just a minor configuration issue on the GT inverter (note: The loss of power occurs only with negative or floating ground systems over maybe 100's of hours of sun. And is "fixed" with something like 10's of hours of positive grounding when exposed to sunlight).

For the people with battery systems--The issues are a bit more complex. Much of the 12 volt stuff out there assumes negative grounding for use in cars and such... So, if you choose to positive ground (like much of the telecom gear), you need to double check everything that they have +/- separate from "earth ground/case ground" connections. Otherwise you do run the risk of making the chassis "hot" with respect to ground (i.e., a car radio connected to a positive grounded solar PV system).

Also, for most PWM solar charge controllers you can ground the panel "-" side and the battery "-" side without issues. But for some of the MPPT charge controllers, they measure current in the negative lead--and if you jumper the panel ground/battery ground around the charge controller, it will not allow it to properly do the MPPT function (cannot accurately measure array current).


Positive Ground vs. Negative Ground Solar Panels???