Another small boat solar question

[mait]

Hello guys,

I have read many threads on the topic and the more I read the more confused i become.

At this very moment I have one 40 or 50W panel with 5A PWM controller, all installed on the cabin top by PO.

There is enough space on the cabin top to upgrade to 100W. And some time later another 100W on the sprayhood top.

My question is - would it be better to add 2 smaller panels 50W + 50W side by side or one 100W panel? I am considering rigid aluminium frame panels. One of the panels (or part of panel if speaking about 100W unit) would get shaded by the mainsail etc time to time.

Next upgrade phase would be adding flexible panel(s) to Sprayhood top. Also the same choice 1x100W or 2x50W. And the same shading problems.

Which route would you take and why?
What controller you would recommend for the setup considering upgrade in two phases?
How would you connect panels in phase A and phase B?

a pic of current panel placement

[john61ct]

The Victron SmartSolar line is my default reco, 75/15 maybe $120.

If two panels are going to be shaded at the same time, could go serial.

If shaded at different times go parallel, but IMO it's also worth going 1:1 with another SC.

If you want to carry a spare anyway, or buy from a source with a good returns policy, easy enough to test yourself for the more efficient option.

[thinwater]

The problem with flex panels on the hood is that they are not made to flex repeatedly. They use the same cells as rigid panels an so require rigid support. The result is MANY stories of short life. Read the fine print in the instructions (look for the Solbian manual on-line).



You would actually be better off with the flex panels on the deck and rigid on the hood. Ironic, isn't it?

[john61ct]

Yes, the flex part is to allow installation on gently curved surfaced.

They still must be perfectly rigid, no flexing once installed in use.

There also must be heat-dissipating material backing the cells, ideally aluminum sheeting with airflow the other side.

Without such ideal mounting, might only average 1-2 years use.

Even with it might only get 5.

Rigid framed often lasts 20. But they're uglier, and heavy.

[mait]

Thanks, already received some good advice.
Coming back to phase A of the upgrade. 100W on cabin top.

Would you recommend 2*50W panels over 1*100W?
One 50W panel left of the centerline and the other to the right.

Victron MPPT would like to recieve higher voltage from panels. In my part of world we have not much direct sunlight.
Would it be better to connect the panels in series to ensure high enough voltage for the SC to start as early as possible? Or connect the panels parallel to avoid loss from shading one side panel by the boom? Maybe Victron MPPT is not the best in that case?

[Pete7]

I would keep it simple and stick with one 100w with the Victron 15/75 John mentioned which will give 5AH in good conditions. If you later decide to add another to the spray hood, the Victron will still be able to cope. Add the USB dongle and you can see what charge they are producing. Note, the very latest ones may have this built in.

Rapidly going off flexible panels, we have one which will be replaced with a rigid panel when it fails and it will.

Pete

[thomm225]

If you don't get a lot of direct sunlight you may want to make it so you can adjust your panels.

In the early morning with my 65 watt panel and 20 watt panel in fixed positions, I get anywhere from 2-5 watts

When I aim that at the rising Sun and retie them, I get 20-40 watts

I have a Victron 75/15 MPPT Controller. A 65 watt panel tied on top of my Aft Lazarette Locker Lid, and two 20 watt panels all rigid not mounted. These are in parallel. (one 20 watt and the 65 watt panel) One is currently on the cabin roof between the hand railing and the sliding hatch

I just received a Renogy 50 Watt Panel plus 10' extension last week that I haven't used yet. It has the MC4 connectors

[Pete7]

Originally Posted by thomm225

If you don't get a lot of direct sunlight you may want to make it so you can adjust your panels.

In the early morning with my 65 watt panel and 20 watt panel in fixed positions, I get anywhere from 2-5 watts

When I aim that at the rising Sun and retie them, I get 20-40 watts

Reminds me we had a suitcase 60w panel (actually 2 x 30w together) until I dropped it, which was used in habour or at anchor and wandered around the deck to face the sun. It was very efficient and well worth moving it several times a day. this might be a better option over a flexible panel on the sprayhood.

[john61ct]

The folding "blanket" style packs seem pretty robust, Australia's excellent consumer protection laws would lead me to start by looking to see what their caravanning forums recommend.