Solar musings - 4 semi-flexible panels and a good MPPT?

[RO'D]

Hi folks, would welcome your thoughts and comments on the below…
I have a 4 Battery domestic bank, total 510 AH. We generally consume 90 AH per 24 hours at anchor here in Spain. Rigid panels are out as we don’t have an arch.
I’m considering installing 4 x 100W semi flexible panels as we want to reduce / eliminate generator use at anchor. Considering Lensun panels rather than the more premium / expensive offerings like Solera / Sunbeam etc.

Panels would be wired in parallel, with a decent 40a MPPT from the likes of Victron / Bluesky, with a Bluetooth dongle.
Basically go premium with the MMPT and mid range on the panels…as I'm not looking at long term usage.

Panels No.’s 1 & 2 would be permanently fixed forward of the cockpit – port and starboard sides of the coachroof.
No. 3 would generally live on the aft bimini, but would need to be removed from time to time.
Panel no. 4 would be the most mobile, generally in the middle part of the bimini / cockpit tent, but would regularly need to be removed.
Panels 3 &4 going into a 2-1 adaptor coming from a cable gland.
Should I perhaps consider two MMPT’s and split the panels into two modules – fwd and aft?
Anything else I'm missing?
Thanks in advance

 

[Mistroma]

I have 145W (2x40W + 1x65W) rigid panels ahead of the sprayhood. They work well most of the time unless sailing or at anchor in certain places (e.g I Guadiana river where tide causes a 180 deg. direction change). I've had them tied to the grab rails for 10 years and slide them out to the guard-rails in places like the Guadiana. I mostly leave them in place with the boom hauled to one side.

I also have a 100W semi-flexible panel but it isn't used mid-season. I'll probably replace it soon as performance has dropped off. Rigid panels are all working perfectly.

I have 200W (2x100W) rigid panels on an arch. I used to have 2x100W semi-flexible on the bimini but they failed very quickly due to flexing.

I use a PWM regulator for the 145W in front of the sprayhood and a small sep. PWM controller for the 100W panel. The 200W aft panels use a good MPPT regulator.

I think you would have problems using a single regulator because they will be partly shade quite often when ones further aft should be unshaded.

I'd suggest 2-3 smaller panels under the boom, linked in parallel. It will improve performance quite a lot as it's often only one panel in shade.

An MPPT will give better performance on cloudy days and outside the main cruising months. I've actually found very little difference between PWM and MPPT on really sunny days in Greece. The MPPT does charge earlier and later in the day when the sun is low but current produced is pretty low and only a few Ah goes into the batteries.

I was actually surprised to find the output of my really cheap eBay controller was close to the expensive PWM and MPPT ones in mid-summer. I've used it as a spare when working on the other 2 units for a couple of days.

My advice would therefore be to use 2 regulators and smaller linked panels under the boom with larger 100W ones further aft.

I wouldn't replace my rigid deck mounted panels with semi-flexible ones as they are in an area I don't ever walk over. I've been meaning to improve their mountings over the past 10 years but keep putting it off. They've never shown any sign of moving, even in gales or medicanes.

 

[noelex]

Should I perhaps consider two MMPT’s and split the panels into two modules – fwd and aft?

Yes, that would be helpful.
When installing multiple solar panels, especially panels subject to differing amount of shadow, multiple solar controllers will produce a slightly higher yield, as well as adding redundancy, usually for only a small extra cost.

 

[RO'D]

Hi folks, thanks for the replies and my apologies for not coming back sooner.
Here's an update on our installation, hopefully it will be of help to someone.
So, we installed 500W in two separate arrays and MPPTs.
The permanent installation is 300W in 3 number Sunbeam Panels on the coach roof forward of the cockpit. These come to a Victron Smart Solar 100/30. And seem to be doing a great job thus far, providing circa 900W on sunny days, here in the Balerics.
The aft array comprises of two 100W Renorgy panels going to a 100/20 Victron Mppt. We haven't used these much yet but they were all good when in use.
They're designed as mobile installations to go onto the aft bimimi during longer spells at anchor. Currently they're under a bunk..
On an aside - a compliment to Lensun - I had originally placed an order for panels but then it emerged they couldn't ship those sizes for several weeks. At my request they immediately agreed to refund my funds, without quibble.
If anyone would like any further info please let me know, happy to help if I can.

 

[[3889]]

Re Lensun panels, have had two and whilst the panels themselves are robust, the junction box is poorly sealed and allows sea water to corrode the conductors. Be prepared to scrape out the poorly applied mastic and replace with epoxy.

 

[Diana1991]

Hi folks, would welcome your thoughts and comments on the below…
I have a 4 Battery domestic bank, total 510 AH. We generally consume 90 AH per 24 hours at anchor here in Spain. Rigid panels are out as we don’t have an arch.
I’m considering installing 4 x 100W semi flexible panels as we want to reduce / eliminate generator use at anchor. Considering Lensun panels rather than the more premium / expensive offerings like Solera / Sunbeam etc.

Panels would be wired in parallel, with a decent 40a MPPT from the likes of Victron / Bluesky, with a Bluetooth dongle.
Basically go premium with the MMPT and mid range on the panels…as I'm not looking at long term usage.

Panels No.’s 1 & 2 would be permanently fixed forward of the cockpit – port and starboard sides of the coachroof.
No. 3 would generally live on the aft bimini, but would need to be removed from time to time.
Panel no. 4 would be the most mobile, generally in the middle part of the bimini / cockpit tent, but would regularly need to be removed.
Panels 3 &4 going into a 2-1 adaptor coming from a cable gland.
Should I perhaps consider two MMPT’s and split the panels into two modules – fwd and aft?
Anything else I'm missing?
Thanks in advance

I have 500W solar going into the Victron 75/15 controller which is 200W. That way I am getting 200W more of the time and never use fossil fuels to charge my batteries even in December. You can't do this with all controllers.

 

[noelex]

I have 500W solar going into the Victron 75/15 controller which is 200W. That way I am getting 200W more of the time and never use fossil fuels to charge my batteries even in December. You can't do this with all controllers.

Welcome to the forum Diana.

This is a serious overload of the controller (assuming your bank is 12v). It is not good practice. You are failing to harvest a considerable portion of your panels’ output and while the controllers self protection mechanism should limit the current it is not designed to function in this way.

The Victron controllers run quite hot even when kept within their design limits. At least make sure that there is plenty of ventilation available to the controller. Much better would be to buy a second controller and wire this to some of your panels.

Victron advise a maximum solar panel size of 200w for the 75/15 (for a 12v bank). These requirements should be taken seriously.

 

[Koeketiene]

Rigid panels are out as we don’t have an arch.

In my experience, rigid panels perform better than flexible ones.
Not having an arch does not exclude mounting rigid panels.

I have two mounted on the pushpit - one either side.
I find it works well.

As for mppt - I can not recommend Victron enough.

 

[geem]

In my experience, rigid panels perform better than flexible ones.
Not having an arch does not exclude mounting rigid panels.

I have two mounted on the pushpit - one either side.
I find it works well.

As for mppt - I can not recommend Victron enough.

View attachment 134394

Or like this. 180w panels wired in series pairs. A set on each side.