Anyone had one of these solar panels?

Colvic Watson · 27 Oct 2011

We're moving to a swinging mooring inn April and we need about 20 amps a day to recharge lighting and water pump use. These looked great value for money - but is it monocrystaline that gets clobbered by line shadows? If so it's no good for us because it will be going on the wheelhouse roof. Thanks. S.

http://www.ebay.co.uk/itm/50-Watt-Solar-Panel-PV-Monocrystalline-12V-50W-T-/370551534001?pt=UK_Gadgets&hash=item564697b1b1#ht_951wt_1348

noelex · 27 Oct 2011

I am not sure where you boat is but you are going to stuggle to get 20Ahrs out of 50w, particularly if you have any shadow problem. The Med in summer you would do it, but the insolation there is about as good as it gets.

Colvic Watson · 27 Oct 2011

Sorry I should have said we were planning on getting two of them - assuming 8 hours of reasonable daylight, and 33% efficiency I reckoned that at a total of 25ah. Am I being unrealistic?

noelex · 27 Oct 2011

100w That sounds much better. Are you in the Uk? Do you need the 25 Ahr year round or only in summer?
Cheap solar panels often have a bit less efficiency and a shorter life than the name brand panels, but if you have the space to mount sufficient capacity the efficiency is irrelevant and the cheap solar panels generally have a life of 5-10 years which is good by marine standards

Billjratt · 27 Oct 2011

I think that each group of 9 'monocrystals' is a "series charge group" giving full output in unobstructed light. So a shadow falling across the array may 'break' any or all of the 4 parallel groups you have, with corresponding performance loss. Unfortunately, even a reasonably thin shadow from a neighbouring yacht spar will break the whole group if one cell is shaded.
Also,it's surprising how angled these arrays have to be in order to get optimum performance, just laying on a wheelhouse roof is not the best,(especially at this latitude) and I've not started talking excrement yet.
I assume it's not windy where you park?

Gordonmc · 28 Oct 2011

I went for polycrystaline panels because of the shadow problem. Also from ebay, but a different vendor.
Two 50 w panels hinged together with 5 meters of cable. Once on board I seperated the panels and wired up. On an overcast day an open circuit was giving me 19v, 5.3 amp from the two in parallel. On the battery I was getting 13.3v across terminals with the panels hooked up which was far healthier than the charge I was getting from a forgen wind-charger.
I haven't done any more tests since as I only wanted to charge my domestic bank for a week before bringing the boat off its mooring. I need to find a permanent location for the panels now.

BAtoo · 28 Oct 2011

On a swinger now; bought a similar 20w version for ours; its mounted horizontally on the hatch garage & so is under the boom; seems to have kept the batteries topped up well between visits. Must say your intended purchase seems a good price....

Ran it through an ebay bought regulator/protector from here http://www.ebay.co.uk/itm/180-WATT-...10763117091?pt=UK_Gadgets&hash=item19c9ff0a23 £19.95

RivalRedwing · 28 Oct 2011

not sure I would go for economy post from Germany...

rogerthebodger · 28 Oct 2011

BAtoo said:
On a swinger now; bought a similar 20w version for ours; its mounted horizontally on the hatch garage & so is under the boom; seems to have kept the batteries topped up well between visits. Must say your intended purchase seems a good price....

Ran it through an ebay bought regulator/protector from here http://www.ebay.co.uk/itm/180-WATT-...10763117091?pt=UK_Gadgets&hash=item19c9ff0a23 £19.95

I got that same regulator from maplin 2 years ago.

A single battery regulator was also available

noelex · 28 Oct 2011

BAtoo said:
Ran it through an ebay bought regulator/protector from here http://www.ebay.co.uk/itm/180-WATT-...10763117091?pt=UK_Gadgets&hash=item19c9ff0a23 £19.95

It looks like a simple switching regulator and there is not float stage. Its worth getting a better regulator especially with 100w.

RobBrown · 28 Oct 2011

I've got an old but good quality 30W panel which is moveable & left on board as close as poss to optimum angle at at approporaiate end of a roughly ne/sw pontoon berth, but even at height of the best days these last 2 summers, never got more than 2.2 amps and average certainly much closer to 1. So max of 8-10 AH per day is my estimate averaged over the summer for that 30w, less outside that season, with shorter days & less and lower sun.

I purchased a two battery PWM regulator from Ebay so can charge both start & house bank from the one panel.

BAtoo · 28 Oct 2011

noelex said:
It looks like a simple switching regulator and there is not float stage. Its worth getting a better regulator especially with 100w.

Yes it is a simple one - no reverse flow and off when full; as I have only a 20w panel going into 140AH battery its fine for me.

As with most things its all a compromise - cost/size/mounting position available/etc. Eventually decided to go for the easiest position to mount & accept what we get out of it & so far seems to be OK.

Might consider a bigger on for next season, probably as an add on for when we are on board - but then there is the storage problem/damage getting it in and out/ how to mount-demount it easily - decisions, decisions

BlueChip · 28 Oct 2011

Changing all (or most) of your halogen lights for LEDs is a good way to save loads of power.

noelex · 28 Oct 2011

BAtoo said:
Yes it is a simple one - no reverse flow and off when full; as I have only a 20w panel going into 140AH battery its fine for me.

As with most things its all a compromise - cost/size/mounting position available/etc. Eventually decided to go for the easiest position to mount & accept what we get out of it & so far seems to be OK.

Might consider a bigger on for next season, probably as an add on for when we are on board - but then there is the storage problem/damage getting it in and out/ how to mount-demount it easily - decisions, decisions

If your using the boat the regulator will be wasting quite a lot of power. If you are leaving the boat the regulator is taking the batteries up to 14.4v every day. Too high for a fully charged battery.
20w is only a small panel so you do not want an expensive regulator, but there are PWM regulators that are cheap and would give you much greater output. Unfortunately you will have to spend a bit more to find one with a float voltage.

I would at least fit a diode in series with the output if you are leaving the boat for a long period with no load. This will drop the voltage about 0.6v which is a more appropriate float level. The diode can be on a simple switch that is on if you are not using the boat.

Colvic Watson · 28 Oct 2011

OK - starting to get complicated with the float charge diode! Yes changed to LED's which basically means they are needed to keep the fridge going without running the engine. Maybe what I need is a smaller unit to top up the batteries during the week and just runny the almost silent Honda genny to charge the batteries.

V1701 · 29 Oct 2011

noelex said:
If your using the boat the regulator will be wasting quite a lot of power. If you are leaving the boat the regulator is taking the batteries up to 14.4v every day. Too high for a fully charged battery.
20w is only a small panel so you do not want an expensive regulator, but there are PWM regulators that are cheap and would give you much greater output. Unfortunately you will have to spend a bit more to find one with a float voltage.

I would at least fit a diode in series with the output if you are leaving the boat for a long period with no load. This will drop the voltage about 0.6v which is a more appropriate float level. The diode can be on a simple switch that is on if you are not using the boat.

I have a 20W & a 40W panel, each of which has it's own PWM regulator, cheap ones from ebay. The 20W panel is connected to the engine start battery and the 40W to the domestic. The batteries are Delphi 110AH maintenance free. I live on the boat and charge small netbook, phone and run lights (LED) from the batteries every day. On a good day the voltage showing at the battery terminals with a multimeter is up to 15.7, I wonder if this is too high and whether I am damaging my batteries...

noelex · 29 Oct 2011

djbreeze said:
I have a 20W & a 40W panel, each of which has it's own PWM regulator, cheap ones from ebay. The 20W panel is connected to the engine start battery and the 40W to the domestic. The batteries are Delphi 110AH maintenance free. I live on the boat and charge small netbook, phone and run lights (LED) from the batteries every day. On a good day the voltage showing at the battery terminals with a multimeter is up to 15.7, I wonder if this is too high and whether I am damaging my batteries...

15.7 is too high for a regular bulk voltage point and will damage the batteries. It my be your regulator has an automatic equalize function that can be changed, but its more likely the regulator is defective or the multimeter is incorrect.
Check the voltage with another mulimeter ( put a fresh battery in the meter as well).

BAtoo · 29 Oct 2011

noelex said:
If your using the boat the regulator will be wasting quite a lot of power. If you are leaving the boat the regulator is taking the batteries up to 14.4v every day. Too high for a fully charged battery.
20w is only a small panel so you do not want an expensive regulator, but there are PWM regulators that are cheap and would give you much greater output. Unfortunately you will have to spend a bit more to find one with a float voltage.

I would at least fit a diode in series with the output if you are leaving the boat for a long period with no load. This will drop the voltage about 0.6v which is a more appropriate float level. The diode can be on a simple switch that is on if you are not using the boat.

Thanks; hadn't thought of that - will fit a Diode for the winter & look around for next season.
Should I fit the diode before or after the regulator??

noelex · 29 Oct 2011

BAtoo said:
Thanks; hadn't thought of that - will fit a Diode for the winter & look around for next season.
Should I fit the diode before or after the regulator??

After the regulator. Between the regulator and batteries. The diode will drop the 14.4v to about 13.8v.
14.4v is better if you are using the boat, but it is too high if the boat is sitting with no load and the batteries are fully charged.

nigelmercier · 29 Oct 2011

Gordonmc said:
On an overcast day an open circuit was giving me 19v, 5.3 amp from the two in parallel...

That's pretty good for 100W panel, got a link?

Anyone had one of these solar panels?

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