First foray into Solar. Advice needed

Jabs

Jabs

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I am just about to fit two solar panels to keep my 540 amp hours of domestic batteries charged, both when sailing and when moored.

I am going to add one panel, probably 150 or 200watts, each side of the boat pivoted on the guardrail. Mono or Poly.

It is likely that one side will be dominant, that is, catching more rays! When the boat is unattended, I will leave them both horizontal.

I have it in mind to use a MPPT regulator for each panel, feeding the bank of batteries.

The boat is in a sunny climate and is alone for weeks at a time.



Thanks to all for any (constructive) comments.

Tony
 
You seem to have it well covered. Definitely MPPT rather than PWM. Not sure why you might want 2 x MPPT controllers. I have one 40A Epever Tracer controlling both 240W panels. I'd get the larger panels. No idea of difference between mono and poly. Dont forget fuses in the right places. Got my system from Bimble in September.
 
Two controllers because one panel will dominate in the morning and the other in the afternoon??

Or am I missing something?

Thanks

Tony
 
Jabs said:
I am just about to fit two solar panels to keep my 540 amp hours of domestic batteries charged, both when sailing and when moored.

I am going to add one panel, probably 150 or 200watts, each side of the boat pivoted on the guardrail. Mono or Poly.
Click to expand...

A hijack/additional related question to the forum if I may as I'm considering something similar having moved away from the concept of fixing panels to the deck.

I'm not keen on the idea of extending the pushpit forward extensively to provide a solid rail to hang panels off. Looking at narrow, semi-flexible 50W panels, hanging them off the upper guardrail with some kind of telescopic strut to angle them looks viable. Wouldn't appear to add more windage than dodgers. Is anyone doing this? And are you sticking the semi-flexible panels to some kind of backing (aluminium/plastic)? photos?
 
The design of the panel attachment is a work in progress. I intend to use the guardrails, not rigid tube.
I anticipate the panels either being rigid and hung from the top rail, extending out as appropriate. I wonder about using the wheels used to keep sails off shrouds to support the panel?

Flex panels on a plastic backing could be good.

Also considered flex panels in an ally frame.

Any other ideas welcomed.

Tony
 
macd said:
Two controllers would only be a benefit if the panels were wired in series...in which case they wouldn't be wired in series:ambivalence:
A single controller (whether MPPT or PWM) will be perfectly happy if they're wired in parallel.
Click to expand...

I don't understand that at all!

Surely connecting two panels with one dominant is like connecting two batteries, one partly discharged???

Can someone help me out here?

Tony
 
Just a thought on solar panels generally. We are considering the need for a bit more power but struggle to find suitable mounting sites. We think we may purchase 2 more panels which we can store safely below decks ( against a bulkhead) without compromising anything.
They will come out when moored without shore power as we would have more sites available when not sailing.
 
macd said:
Two controllers would only be a benefit if the panels were wired in series...in which case they wouldn't be wired in series:ambivalence:
A single controller (whether MPPT or PWM) will be perfectly happy if they're wired in parallel.
Click to expand...

Parallel or serial? As I understand it the MMPT controllers are more efficient wired in series with the higher voltage. But that does not take into account shading, which will affect both panels output in serial but only one in parallel. Typically at least one panel will have a strip of shadow across it much of the time.
That came from the Bardon expert on the SBS stand.

Things to note also
Make sure the wiring is properly sized so that you do not get a loss of voltage (or a fire!)
Check where shade is least (and assume ayacht alongside will cast shade.)

I have mounted mie 2 x 85 watts on my quarter guard rails - plenty of space on an oceanlord as its a centre cockpit - I get 8-9 amps at the controller and going into the batteries in the best conditions. My Panels will lower INSIDE| the guard rails so wont foul other boats. I do hate going stern too to find the sunpanels of a yacht sticking out and asking to be bust - its the last thing you want to worry about when berthing in wind.

Jags - if you PM me with your email address I will look out some pics of how it works.
 
Chris_Robb said:
Parallel or serial? As I understand it the MMPT controllers are more efficient wired in series with the higher voltage. But that does not take into account shading, which will affect both panels output in serial but only one in parallel. Typically at least one panel will have a strip of shadow across it much of the time.
Click to expand...

Exactly so, Chris.

We have 4 x 85W panels, currently wired in series on a stern arch (so a nominal 80V). Although they generally deliver the power you'd expect from their rating, inevitably one or two often suffer some shading from the backstay. When I get round to it, I'll wire them as parallel/serial pairs. (So 170W at 40V each). In the meantime, they usually deliver more power than we need, which is why it's not at the top of the list.

And note to Jabs: one controller, whichever configuration we adopt.
 
I have 2x100W panels on a simple single tube arch over the stern of my centre cockpit Moody. Panels are mounted on NOA fixings so they can rotate fore and aft according to sun position. Installed early last year they are wired in series and feed into a Victron MPPT controller with a capacity of 100v and 30A so plenty or room to expand. In Greece they keep my 475AH domestic bank well up to charge, usually in float mode during the morning.
My understanding there is no benefit to 2 controllers when they are wired in series. I have vague plans to increase battery bank size and install a 3rd 100W panel but not really needed at this time so only a vague plan. My set up typically delivers 12 - 16A to the battery bank for much of the day if I adjust panel angle a couple of times during the day
 
As others have probably said, definitely use one MPPT controller and that will provide you with the maximum output. If you use two controllers in any configuration you will spend more money and get poorer performance. :(

Whether to use parallel or series is more complicated. If, in general, neither panel is shaded any of the time, then definitely wire the panels in series and buy a controller which can cope with the combined voltage, probably around 45V. The current will not be a problem.

If, in general, at any given time one of the panels has some shade across it and not just a shadow of a halyard but something more solid perhaps covering 10% of the panel or more, then wire the panels in parallel ensuring that that the controller can cope with the combined maximum current for those more unusual occasions when both panels are in full sun.

When I bought my 4 panels I bought enough connectors to be able to try every configuration and when I installed them I left enough spare panel to controller cable to allow me to experiment with both 2P in series with 2P and 2S in parallel with 2S. It's then easy to switch things around if you get it wrong first time .... which is what I did. :o

Richard
 
RichardS is correct - I did much the same, having two 420W on an arch and another on the deck all wired to a single Outback controller. I can select between the panels or run them together.
 
I have two 60 W mounted on a solid extension to me pushpit, they are solid framed panels, hang down from the top of the panels, so are level with the new extentded 25 mm tube. I have two gas struts to lift them horizontal with cords into jammers so they can be set at any angle between horizontal and vertical, they are both connected through a mppt controller seem to keep my 330 AH fully charged. I plan to put the same setup on the other side, all I need now are batteries that hold their charge, mine are 5 years old now and are quickly discharged. I will post some pictures of my setup when I find them. https://www.dropbox.com/s/fb2zrgz52uz3pux/IMG_0696.JPG?dl=0 https://www.dropbox.com/s/hkmoa1fbh2wo7n9/IMG_0706.JPG?dl=0 these are two pictures of my solar panels
Mi,e
 
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macd said:
Before we debate that, you're going to have to explain how you can realistically wire them in series with a controller apiece.
Click to expand...

Maybe my poor use of words!
What I was trying to say is there is no benefit of 2 controllers if the panels are wired in series. I'm not sure why there would be any benefit of 2 controllers anyway but wiring the panels in series means the voltage output rises to the point of the controller starting to put out a charge to the batteries more quickly. I'm pretty sure you know more about this than me anyway but was trying to reinforce the message to OP.
 
rich said:
Why flexible panels, if you are then going to make them ridged?
Click to expand...

semi-flexible are thin and relatively light. A look at the photonics universe site shows their rigid 50W panels as 4.2Kg whereas the semi--flexibles are 1.3. I don't fancy hanging rigid panels off the guard rails although maybe I shouldn't worry about it.

Chris_Robb has a similar boat to me but has an extended pushpit with steel tubes. It's a nice set-up (I've seen the pictures :-) but I was wondering whether semi-flexibles might be an alternative to getting the pushpit steelwork extended which I'd prefer to avoid if I can.
 
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