For North Europe / UK - Solar panel to maintain house bank with fridge unit.

[Refueler]

OK ... based on noelex comment about splitting the panels to own controllers ... and wanting folding panels so I can stow away easily ... semi rigid etc.

I have ordered two of these :

100W 18V Solar Panel Kit Foldable Portable Solar Panel With Waterproof MPPT | eBay

I do not believe at 58 x 28cms they can deliver anywhere near 100W each ... but the size is convenient and handy .. Having two and separate controllers may help ....
The other I considered

100W 12V faltbares tragbares solarpanel für Powerstation Wohnmobil Camping | eBay

are 63 x 46cms and more believable for output .. but are not so handy size to stow.

 

[lustyd]

Not wishing to be Debbie Downer, but those (first link) seem to have 8 cells which would put them at about 4V. Even if we assume the tiny strips are individual cells it would only make 16V which isn't sufficient for an MPPT. It might charge a phone.
If we assume that box actually is an MPPT, the connections aren't large enough for 100W with cable long enough to get to the deck without voltage drop.

Second link does look believable and dimensions are slightly larger than my Renogy 100W as you'd expect with the hinges etc.

 

[B27]

Having multiple controllers can mean different things.

You can have an MPPT system to extract the best power from each panel.

Or you can have two battery charge controllers trying to smart charge the same battery.

Your typical 'solar panel controller' is both some sort of converter which may or may not actually be MPPT, and some sort of battery charging regulator.

The cheap chinese controllers are a bit of a joke, they just about do a basic job if used as intended, but they are not all the same.
Could be a bit pot luck if you wire multiple controllers to the same battery?

 

[Refueler]

I have a 'cheapo' chinese PWM controller working on Superanne .... works a treat ... came as a set ...

On Anisette - I swapped out the NAPS NC5 for a cheapo PWM controller as the NC5 only had a couple of LED's to indicate anything ... the cheapo gives me info of voltage etc etc.

 

[Refueler]

I am not expecting miracles with the panels ordered ... if they prove poor - then I have other work for them ... so not wasted.

I'm stuck in the 'space needed' for decent sized panels ... etc.

 

[NBs]

Hi,
I have this panel and it is very handy because it comes with 4 support legs. I have tied about 60cm of 6mm rubber rope to the handles and I can tie it in several places on the boat and even strong winds are not a problem. The panel also produces well vs the price.

Sory, i have eco worthy 100W loks like same...

100Wp 12V Faltbares Solartasche für Camping | ECO-WORTHY

 

[fredrussell]

OK ... based on noelex comment about splitting the panels to own controllers ... and wanting folding panels so I can stow away easily ... semi rigid etc.

I have ordered two of these :

My guess is at that size they’re 50watt total, so if you have two, plus the one on boat that gets you to 150 watt or so, so should cope with fridge on all but grey days I would have thought.

 

[noelex]

The advantage of multiple controllers only applies when using MPPT controllers. There is no advantage in solar production when using multiple PWM (or more correctly non MPPT) controllers.

Some controllers advertised as MPPT controllers are really just PWM controllers. Others are only able to modify their input voltage in a very crude way, so while strictly speaking the MPPT label is correct, the overall performance is significantly worse than good quality MPPT controllers.

So while multiple controllers are beneficial, swapping a single good MPPT controller for several poor MPPT controllers (perhaps for similar overall cost) may be counterproductive.

However, because each controller can be smaller, in some cases you can swap one larger good quality controller for a couple of smaller good quality controllers for not much extra cost.

 

[B27]

....

So while multiple controllers are beneficial, swapping a single good MPPT controller for several poor MPPT controllers (perhaps for similar overall cost) may be counterproductive.

However, because each controller can be smaller, in some cases you can swap one larger good quality controller for a couple of smaller good quality controllers for not much extra cost.

Have you tried multiple controllers?
Did you see any issues with e.g.
One panel is charging the battery slowly, say 14.0V
Second panel sees some sun, its controller wakes up, senses battery fully charged so goes into float charge mode?

If the controllers are more sophisticated, e.g. communicating with a shunt, this could be avoided.

 

[noelex]

Have you tried multiple controllers?
Did you see any issues with e.g.
One panel is charging the battery slowly, say 14.0V
Second panel sees some sun, its controller wakes up, senses battery fully charged so goes into float charge mode?

If the controllers are more sophisticated, e.g. communicating with a shunt, this could be avoided.

You are certainly not alone with this concern, but it is not worry.

We use multiple controllers on our current yacht. We have over the years used most permutations from no controller (in the "good old days when these were very expensive), PWM controllers (before MPPT controllers were available), a single MPPT controller, a single MPPT controller linked to the battery monitor, and finally multiple controllers. Multiple controllers have been the best solution, but this has only become practical in recent years with the availability of inexpensive, good quality MPPT controllers that have low self consumption.

A controller that wakes up and measures a battery voltage of 14.0 V would still attempt to complete its charge algorithm (assuming there is enough solar energy for this). This means raising the battery voltage to the absorption voltage (for example 14.6v) and holding at this voltage for the absorption time (for example two hours) and then dropping to a float voltage.

There are some slight variations and exceptions. The Victron controllers use an adaptive absorption time that will reduce the absorption time based on the wake up voltage. This can be turned off if you wish, but in most cases if the battery voltage is high at dawn, reducing the absorption time is sensible. Finally, there are sophisticated solar systems that can communicate with the battery monitor to determine the battery SOC. These work differently, but will charge the battery more accurately.

 

[Boathook]

A bit late joining in ....

I replaced my 50W and 30W 7 year old spectra panels with a new 150W one. One sunny day in early June it was producing 130W for a short period (according to my victron smart controller) and it is mounted flat. It now keeps up with all the electronics, etc. I suspect that it would not keep the batteries up to run a fridge but my fridge is gas. Shade does affect it, but not as much as the previous ones.

I've been most impressed by how the solar panel 'output' has improved over the years. My next upgrade would be to replace the lead acid batteries with possibly AGM or maybe the lifepro? ones, but I will wait for the LA ones to fail first. I suspect that I will also try to increase the solar panel output but trying to find a spot not walked on isn't easy and I don't want the agro of getting out portable panels, etc

 

[Refueler]

This is an area I tend to think can be expensive or economic depending on how far you are pushing the solution.

Lets look at my situation ...

Most of the time - boat will be plugged in and mains chargers .... so as long as I have chargers of suitable output - I'm ok.
There will be three forms of sailing :

1. Short day sailing to try out and arrive at trimming / understanding boat for racing ... Solar will be last thing on mind !! Engine run max 1hr out .. 1hr return.
2. Up to 7 days of multiple leg racing with daily stops - usually mains again when tied up. Similar 2hrs engine per day as #1
3. Cruising Baltic where it will be a mix of ~70% no mains hook-up ... 30% mains available over period of 7 - 10 days. Likely 2 - 3hrs engine per day depending on wind.

I don't have any inverters or hot water stuff ..

Appliances demand priority >
Plotters (Garmin and Onwa)
Tillerpilot AH1000
B&G Network displays
VHF

Secondary demand >
Fridge
Music
Intermittent Computer (work sadly cannot be ignored).

Compared to some boats I see ... smaller boats !! - my demands are small ... and I hope that once I get used to the demands and observe over time - a regime can be arrived at .. its still early days of using this boat .. so its a lot of ifs and maybe's at present.

 

[B27]

Plotters can be quite thirsty?
Simple instruments don't use much.
Car type stereo units can be wasteful.

It's cool enough in July, I think the heater could be a consideration before September is out.

 

[Refueler]

Plotters can be quite thirsty?
Simple instruments don't use much.
Car type stereo units can be wasteful.

It's cool enough in July, I think the heater could be a consideration before September is out.

You'd be surprised at temps here in Baltic ... we have a large difference winter - summer ....

 

[Laminar Flow]

In Northern Europe, i.e around 49 parallel, you can expect a max average solar output of 4 x your panel watts in Summer. Figure a min of 40 A consumption for the Fridge alone, depending on ambient temp, of course.

We installed 300 W in 6 x 50 Watt panels, as shading is a serious consideration on a sailing boat. This we coupled with a MPPT charger to a house bank of 2 x 200 A of lead acid. With this set up we were fully autonomous (we live aboard 4 months of a year). Ketch rig with lots of wires and bits.

For longer passages in Northern waters, i. e. up to 4 days and nights, when the AP is working continuously along with the fridge, nav instruments, nav lights, tablet charging, Webasto, etc, etc, we added two more semi flexible panels of 120 Watts each on top of the canvas bimini. This has worked well in Norway, Denmark, Sweden, Shetlands and Northern Scotland as well as the North and North West coasts of France.

We do not bother to adjust any of the panels for sun angle or shading. Aparently, the sun doesn't always shine either, especially in the areas mentioned and running a 60 hp diesel to charge your batteries is nuts.

 

[Refueler]

Pals boat - he has mounted 120W flexi panel on his sprayhood ... but he has said that it does not keep up with his fridge .. that he has calculated need to at least double up to 240W ...

 

[B27]

Pals boat - he has mounted 120W flexi panel on his sprayhood ... but he has said that it does not keep up with his fridge .. that he has calculated need to at least double up to 240W ...

Unfortunately there are some very poor flexi panels about.
Also sprayhoods get a lot of shading and often slope the wrong way.

There's also the effect with a flexi panel, when you flex it, it's not all pointed the same way, so you have cells in weak sun in series with cells in stronger sun. I suspect that 'shortens the day for solar generation' sometimes.

One thing I found quite useful is having a small rigid panel of known power and quality, to 'calibrate' and sense check what I'm getting from other panels. I use an old 10W panel which I used to have for trickle charging.

Another useful thing, you can get cheap DC Ah meters on ebay for about a tenner.
It's good to have a baseline of what the fridge typically uses.

Also useful, I keep an eye on a local internet connected array on someone's house.
Yesterday wasn't really very 'sunny', and I got pretty wet walking to town, but this 4kW array produced 26kWh in the day.
As of 1030 today, it's managed 1.6kWh.

Having two panels on the sprayhood, so one of them is very often in full sun, could be a good move.