Upgrading existing solar setup

[Tim Good]

Ok after some good advice on here I have come to three conclusions:

1. Don't bother with a wind gen quite yet and maximise solar first.
2. Stick to solid mono panels if I can.
3. Cheap panels are nearly as good as the expensive ones apart from the non marine connections

So I am taking down my 120W solara panel which hang off the back of the goal posts. I will replace with 2 new 120W cheap panels from ebay.

http://www.ebay.co.uk/itm/111684175...49&var=410691500466&ssPageName=STRK:MEBIDX:IT

These are a good size being square-ish and I can mount two of them side by side easily. I plan to wire them in parallel to make a single 240W setup running into my current Sunware Control rated up to 250W / 16amps.

I will then put my single Solara panel on the coach roof via a new controller which I'm yet to buy. Total theoretical output = 360w.

Does all that sound ok and do the specs on the ebay page for voltage of these panels look doable?

 

[rickym]

Where are you based? Maybe OK for summer in the Med or Portugal but our experience in the Caribbean is the daylight hours are shorter than a european summer and there are many cloudy days. We had just solar in europe but added a wind gen when we got to the caribbean. Still have times when no wind or sun, but that's what you have a honda for!

 

[Tim Good]

Where are you based?

UK no but doing a circumnavigation soon so everywhere. Anyway I just want to make sure I have the fundamentals right in terms of setup more than anything.

 

[macd]

...Does all that sound ok and do the specs on the ebay page for voltage of these panels look doable?

The spex look pretty routine for on- and off-load voltages. If your energy use is modest (didn't you write a rough budget in one of your previous threads?), 360W (potentially) isn't at all bad. However, if you're Carib-bound (and Patagonia, did you once mention?) I'd agree with rickym that ideally a contribution from wind would be desirable. The Carib can be suprisingly cloudy, the December sun's lower than Glasgow in June and the days aren't long. But, usually, it'll be sunny soon...
Patagonia I've no experience of, but I doubt it's one of Ambre Solaire's major profit centres.

We are expecting a digital postcard, by the way (even if it only tells us our advice was carp).

 

[Mistroma]

Points 1-3 are spot on. Someone always suggests that a wind gen is a good idea and it is often said that solar in UK won't give great results. However, you have taken onboard the fact that solar is the cheapest option by far. A wind gen. is worth having if you have lots of cash leftover after fitting all the solar panels you can manage.

I have often suggested use of the online Photovoltaic Geographical Information System (PVGIS) to get a rough estimate of solar output. It works well for Europe and includes a decent allowance for various losses. It obviously only gives a figure for an average year but I find that predictions are usually quite close to actual performance.

PVGIS predicts following daily outputs for 360W panels in Bristol area

May.......112
June.......119
July........112
August..91

Once you get to Lisbon, the figures become
May.......151
June......162
July.......163
August..146

These figures are the predicted Ah/day for 360W panels lying flat and not subject to any shading. Output drops off rapidly outside the months listed. I can quote for full year if you are interested .

Unfortunately, online PVGIS uses a European database and so I can't calculate figures for the Caribbean. However, I'd still expect daily output in June/July to be around 140-150Ah/day with 360W.

These figures just a starting point. You will get less if panels are shaded, you fit undersized wiring etc.

 

[geem]

We are in the Caribbean. We have a wind Turbine and 380w of solar. The wind turbine is a pain. It's noisy so we tend to tie it up at night unless it's a very windy night when I can't resist the amps it produces. We then relie on ear plugs!
Having your panels flat does lose out on lots of amps. We have ours on the guard rails so we can tilt them. The port guardwires have two 75w panels and same on starboard. The starboard ones are tilted during the day to maximise output. The port panels stay horizontal. We also have two roving 40w panels on long leads that we can move around at anchor. We seem to get as much output from this set up as our friends with 500w of panel sat horizontal on his monkey bars ( sorry, stern arch).
We wouldn't fit a wind turbine again but ours is a Duogen. Next time we would go for the towed only Duogen option. It's nice to leave an anchorage in the morning and arrive at the next anchorage after a few hours sail all charged from the solar and towed generator. I don't like sailing with a wind turbine going around.
Incidentally, our friends have a Rutland 913. The output of that unit here in the Caribbean is poor. His view also would be to not bother with a wind turbine if it was to fail. Solar is way superior and if you can tilt it you get more amps

 

[RAI]

You don't mention your battery capacity, it's worth having plenty. My limited solar set up manages to keep the batteries in the 60% morning to 80% evening charged range. I suspect the battery bank can absorb more Ah in this range. Trying to keep them full off solar seems wasted effort. They need pumping up to 100% with the alternator occasionally.

 

[geem]

You don't mention your battery capacity, it's worth having plenty. My limited solar set up manages to keep the batteries in the 60% morning to 80% evening charged range. I suspect the battery bank can absorb more Ah in this range. Trying to keep them full off solar seems wasted effort. They need pumping up to 100% with the alternator occasionally.

Another thing to think about is that if you use AGM batteries they need an occasional full charge from a good mains charger otherwise they lose capacity. Being in the Caribbean, we haven't been in a marina for over a year. We don't have AGM batteries but you may find you need to boost charge your batteries occasionally.
We tend to leave the mains charger on when we make water from the watermaker. This bangs 30 amp @ 24v for an hour every three days. If we do this in the morning when the batteries are at their lowest the solar has them at a high voltage for the rest of the day which should help reach a full charge.

 

[Mistroma]

Another thing to think about is that if you use AGM batteries they need an occasional full charge from a good mains charger otherwise they lose capacity. Being in the Caribbean, we haven't been in a marina for over a year. We don't have AGM batteries but you may find you need to boost charge your batteries occasionally.
We tend to leave the mains charger on when we make water from the watermaker. This bangs 30 amp @ 24v for an hour every three days. If we do this in the morning when the batteries are at their lowest the solar has them at a high voltage for the rest of the day which should help reach a full charge.

Not just AGM, same applies to all lead/acid batteries. Best to get to 100% every day or at least once every month as a reasonable minimum. Even better to keep at 100% all the time for longest life, but not much point in having them on a boat in that case . It's a matter of finding the sweet spot to match usage, battery type, capacity and charging kit in order to get the best return for your money.

I also aim to run a generator when batteries are low and a 09:00 start is a decent compromise to minimise disturbance. The mains charger pumps out full output for about 1-1.5 hours and solar tops up for the next 8 hours in summer. I agree that this is a much more sensible approach than running the generator later in the day. That tends not to achieve full output from the charger and the top up is only for an hour or so. However, I have flooded batteries rather than AGM.

 

[geem]

Not just AGM, same applies to all lead/acid batteries. Best to get to 100% every day or at least once every month as a reasonable minimum. Even better to keep at 100% all the time for longest life, but not much point in having them on a boat in that case . It's a matter of finding the sweet spot to match usage, battery type, capacity and charging kit in order to get the best return for your money.

I also aim to run a generator when batteries are low and a 09:00 start is a decent compromise to minimise disturbance. The mains charger pumps out full output for about 1-1.5 hours and solar tops up for the next 8 hours in summer. I agree that this is a much more sensible approach than running the generator later in the day. That tends not to achieve full output from the charger and the top up is only for an hour or so. However, I have flooded batteries rather than AGM.

From what I understand, AGM are more prone to failure if not achieving 100% periodically. Budget Marine here in the Caribbean have this specific advise for AGM batteries in their catalogue. Apparently there have been a number of warranty claims on AGM batteries failing that have been due to this lack of full charge. They do not have the same warning on sealed or conventional batteries. Mine are sealed batteries but if I could fit Trojan batteries I would be tempted to go that route. My battery box isn't large enough to accommodate the number of Trojans I would want.

 

[Mistroma]

From what I understand, AGM are more prone to failure if not achieving 100% periodically. Budget Marine here in the Caribbean have this specific advise for AGM batteries in their catalogue. Apparently there have been a number of warranty claims on AGM batteries failing that have been due to this lack of full charge. They do not have the same warning on sealed or conventional batteries. Mine are sealed batteries but if I could fit Trojan batteries I would be tempted to go that route. My battery box isn't large enough to accommodate the number of Trojans I would want.

Interesting, I hadn't heard of such issues before now. I had assumed that AGM would behave in a similar manner to flooded cells wrt repeated charging to under 100%. I know that they have a much lower self-discharge rate and can stand storage better than flooded cells. I suppose that simply means that they remain at a higher state of charge for longer in storage and suffer less from sulphation. I assumed sulphation effects would would be similar when operating below 100%. After a little thought, this does not actually follow from better storage performance.

I wonder why AGM might be worse? There's no free electrolyte and I imagine that the plates will be closer together than in flooded batteries. That might allow faster crystal growth and also make bridging more likely as crystals can't fall to the bottom of the cell. No idea, but would be interesting to see if anyone can explain it.

My battery box wasn't big enough for T105s either, but glad I rebuilt it to add the extra space.

 

[geem]

Interesting, I hadn't heard of such issues before now. I had assumed that AGM would behave in a similar manner to flooded cells wrt repeated charging to under 100%. I know that they have a much lower self-discharge rate and can stand storage better than flooded cells. I suppose that simply means that they remain at a higher state of charge for longer in storage and suffer less from sulphation. I assumed sulphation effects would would be similar when operating below 100%. After a little thought, this does not actually follow from better storage performance.

I wonder why AGM might be worse? There's no free electrolyte and I imagine that the plates will be closer together than in flooded batteries. That might allow faster crystal growth and also make bridging more likely as crystals can't fall to the bottom of the cell. No idea, but would be interesting to see if anyone can explain it.

My battery box wasn't big enough for T105s either, but glad I rebuilt it to add the extra space.

We have 800 amp hour of domestic battery bank plus two 110 amp hour starting batteries. This lot takes up our whole starboard saloon area under the seats. No easy way of eextending it so we are stuck with sealed lead acid batteries.
Next time I go for new batteries which I hope will not be for a few years I will look for large traction batteries.
I have added a 30 amp@24v smart mains charger fed from our generator to ensure I give maximum input to our batteries when I am making water. I will be adding another one in parallel and using the desulphation cycle periodically when I can move a few things around to make the space for second charger.

 

[syneraida]

The sizes and specs seem reasonable to me, I would suggest that the key is not how much solar you have, but how much power you use, what I mean is that I think its better to find efficiencies in your power consumption where you can, then figure out how much you use, then spec your setup accordingly.

We need about 300w of power under sail and have about 200w, so need to run the engine every couple of days (we have 500ah of batteries), but for the time being it works ok for us and with a bit of luck we'll get a towed water generator for when we're sailing (at anchor 200w is fine).

If you want to see/read about our setup have a look here.....

http://syneraida.com/?p=4242

Solar VS Wind seems to be almost as conversation generating as "which anchor should i buy", honestly I don't much like wind generators and do not find them very useful in the Med. or when downwind sailing, but in some places (like the Caribbean) there is a lot to be said for them at the end of the day everyone makes their own choices.

 

[RAI]

No idea, but would be interesting to see if anyone can explain it.

With wet cells one can let the charging system switch into that equalisation phase and not worry to much about its duration, it just uses up more water. I think AGMs need more careful treatment as they might start gassing and blow their over-pressure valve. My charger provides AGM settings that seem to be slightly lower voltages than for my wet cells.

There's a better explanation here
http://www.chargingchargers.com/tutorials/charging.html

 

[Garry & June 'Friendship']

We are fortunate in being a multihull and therefore plenty of space for panels. We have x2 rigid fixed on a rear archway and x2 semi flexible on the cabin roof...they are all 100w. These feed in to a MPPT controller which has a dedicated permanent trickle feed to the 2 engine batteries which keeps them constantly at full charge. Our domestic bank of 450 A/h of AGM's are usually fully charged by 10.00am here on the Algarve and we agree it helps on every occasional trip in to a marina to give them a boost from the charger. One thing I do agree with is you do not need to fork out the astronomical prices being asked for 'marine panels'...I was quoted around £600 for one at SBS a year ago which is crazy. I paid around £140 each for mine and they have performed superbly this year on our way down to the Med and are still in as new condition.

 

[whiteoaks7]

I've just updated this for PBO: http://www.pbo.co.uk/expert-advice/solar-panels-everything-you-need-to-know-24455 so might be worth a look. The only worry I have is that your panels in parallel will bang out more than 16A in the best conditions. No reason why you shouldn't get 1kW/m^2 which will generate 2x120W / 12V = 20A (and better if you can use an MPPT controller). I guess I would put the two in series and use my favourite Victron 75/15 but that's only my opinion. (ps - forgive me if I'm repeating anything - I've not had time to read all the posts). PM me if you have anything I can help with.

 

[Tim Good]

We are fortunate in being a multihull and therefore plenty of space for panels. We have x2 rigid fixed on a rear archway and x2 semi flexible on the cabin roof...they are all 100w. These feed in to a MPPT controller which has a dedicated permanent trickle feed to the 2 engine batteries which keeps them constantly at full charge. Our domestic bank of 450 A/h of AGM's are usually fully charged by 10.00am here on the Algarve and we agree it helps on every occasional trip in to a marina to give them a boost from the charger. One thing I do agree with is you do not need to fork out the astronomical prices being asked for 'marine panels'...I was quoted around £600 for one at SBS a year ago which is crazy. I paid around £140 each for mine and they have performed superbly this year on our way down to the Med and are still in as new condition.

Do you feed the flexi panels on the roof into the same controller as the ones on the archway? How are you feeding those in? Each pair in series to make 24v and then both 24v in parallel at the controller?

 

[Mistroma]

With wet cells one can let the charging system switch into that equalisation phase and not worry to much about its duration, it just uses up more water. I think AGMs need more careful treatment as they might start gassing and blow their over-pressure valve. My charger provides AGM settings that seem to be slightly lower voltages than for my wet cells.

There's a better explanation here
http://www.chargingchargers.com/tutorials/charging.html

Only spotted this explanation. Yes, I know that prolonged equalisation wouldn't be good for AGMs as they have no free electrolyte. However, I was discussing the earlier statement that "AGM are more prone to failure if not achieving 100% periodically". I was commenting on failure when undercharged and that's why I mentioned sulphation and crystal growth.

I don't think that gassing at equalisation voltage explains premature failure of permanently undercharged AGMs. I found it odd that geem noticed a specific warning about AGM failures due to undercharging but nothing about flooded batteries from same retailer. Nobody else provided another explanation, perhaps they just had a dud batch of AGMs in stock.

 

[geem]

Only spotted this explanation. Yes, I know that prolonged equalisation wouldn't be good for AGMs as they have no free electrolyte. However, I was discussing the earlier statement that "AGM are more prone to failure if not achieving 100% periodically". I was commenting on failure when undercharged and that's why I mentioned sulphation and crystal growth.

I don't think that gassing at equalisation voltage explains premature failure of permanently undercharged AGMs. I found it odd that geem noticed a specific warning about AGM failures due to undercharging but nothing about flooded batteries from same retailer. Nobody else provided another explanation, perhaps they just had a dud batch of AGMs in stock.

I did some more research on the Budget Marine wording in their catalogue.
Apparently Lifeline brand AGM batteries had a number of failures and warranty claims in the USA. The manufacturer now will not warrant the AGM batteries if they are not being charged to 100% on a regular basis. They put this lack of a full charge down to their premature loss of capacity and ultimate failure to hold charge. Since Budget sell AGM batteries they have passed this advice on to their customers. They don't offer the same advise for sealed and/or wet cell batteries. I don't know enough about batteries to comment on why AGMs may be more prone to failure if not regularly charged or wether Lifeline batteries are not as good as other AGM batteries but I thought it was worth sharing.

 

[Mistroma]

I did some more research on the Budget Marine wording in their catalogue.
Apparently Lifeline brand AGM batteries had a number of failures and warranty claims in the USA. The manufacturer now will not warrant the AGM batteries if they are not being charged to 100% on a regular basis. They put this lack of a full charge down to their premature loss of capacity and ultimate failure to hold charge. Since Budget sell AGM batteries they have passed this advice on to their customers. They don't offer the same advise for sealed and/or wet cell batteries. I don't know enough about batteries to comment on why AGMs may be more prone to failure if not regularly charged or wether Lifeline batteries are not as good as other AGM batteries but I thought it was worth sharing.

The penny has finally dropped and I've remembered a few things from 2011 when I was last in the market for new batteries. One reason I went for T105s instead of AGM were the failures reported on Morgans Cloud site and reading that part of the fix appeared to be regular equalisation charges. Good AGMs were 2-3 times the price of T105s and cheaper one's didn't seem to be designed for deep cycling. Paying a lot more and still risking early failure didn't seem like a good idea.

However, I knew that all lead acid batteries suffered from sulphation due to undercharging. I assumed that AGM and flooded would be affected equally but that still made the cheaper option a safer bet financially. It sounds as if my assumption might not have been correct. I guess it makes sense that bridging might be more likely with smaller plate separation but there are a lot of factors. So still wondering if anyone knows why AGM would be more prone to sulphation than flooded cells.

I'm still happy with choice of T105s vs. AGM but I don't mid spending time maintaining them. Sorry about the thread drift.