How much solar do you have?

[Graham376]

2 x 160W in parallel on gantry. 450AH Trojans. Victron 100/30 indicates min overnight battery voltage 12.23v , max charge 1.51 kWh. 12.45 hrs now, already on float 13.42v. Main load is fridge on 24/7.

 

[Roberto]

I have 300W on a stern arch. We left for a first family Atlantic circuit (then very young daughters) with 200W and it was ok, for the second similar trip I decided to up to 300W to be a little more comfortable: daughters had grown up and accumulated all sorts of devices, basically all the output from the third 100W panel disappeared into charging phones, PCs, cameras, Ipads Ipods Ipeds Ipids, etc etc. They were homeschooled so they were only learning aids, supposedly.

 

[john_morris_uk]

Swap to lithium batteries and you will get an instant leg up in solar performance. In my experience about a 50% increase in daily solar harvest

We might consider Lithium when the Lead Acid give up the ghost. However while they are functioning perfectly adequately I don’t feel like spending lots of money to change!

 

[Kelpie]

But doesn't swapping to lithium for domestic batteries also involve changing a lot of ancillaries such as voltage regulator, charge splitter, mains charger, solar charger? I can see the benefit, and that the engine battery can be kept separate, but it's the engine charging of both engine and domestic batteries that would need a sophisticated charge splitter?

And will lithium emergency start the engine OK?

Depends on what you already have installed. Most MPPTs will have a lithium setting. Better shore power chargers will too.
I took the unusual step of solar-only charging for my lithium. And then sailed somewhere sunny

 

[lustyd]

China is the land of facades and short cuts

I'd argue that China is the land of get what you pay for. They have very cheap options which perform as expected for the price. They also make most of the expensive stuff we buy elsewhere, which also performs as expected. They do generally understand the value of things though, and rarely rip people off.

 

[dankilb]

Currently 260w via two aged, but still functional, rigids on the rails.

Aiming for 1000w when we eventually complete our refit (41’ AWB) but without an arch.

Planning to fabricate something that will allow a large-ish square panel to be permanently mounted on the ‘hatch garage’ (coachroof) with two further panels of the same size that can be slid out on either side to lie over the coachroof when not underway. Guess shading may be an issue but seems a possible way to get 3 for 1!

That plus upgrading the guardrail mounted panels, and adding one more on the foredeck, will hopefully allow us to swerve the weight and expense of an arch/gantry and get close to 1000w.

 

[Kelpie]

I'd argue that China is the land of get what you pay for. They have very cheap options which perform as expected for the price. They also make most of the expensive stuff we buy elsewhere, which also performs as expected. They do generally understand the value of things though, and rarely rip people off.

Yes I'd agree with that. AFAIK all lithium cells come from China.
If you go the DIY route your at least get a bit more control over what is going on, vs a sealed box which may or may not contain the advertised components.

 

[geem]

I'd argue that China is the land of get what you pay for. They have very cheap options which perform as expected for the price. They also make most of the expensive stuff we buy elsewhere, which also performs as expected. They do generally understand the value of things though, and rarely rip people off.

That isn't my experience commercially. They love to hook you in with their product that meets an agreed standard then over time, whilst you aren't watching they lower the standard. See some of the batteries Will Prowse has tested where they did just that. It happened to a friend of mine having stuff built in China. Look at Chinese 316 stainless steel. Lots of it is utter crap

 

[noelex]

We have just over 1000w. This has been plenty for us to manage everything we need including electric cooking and water heating, providing we are not in areas with very poor solar insolation. We also have a large 3 Kw alternator. In practice we do few engine hours so this contributes little, but it does provide an alternative redundant system without the hassles associated with a generator.

The only time we have thought about rationing electrical power was in winter in Scotland, but here we switched over to cooking and water heating on our diesel reflex heater, we collected rainwater (so need to run a watermaker) and our fridge and freezer consumed minimal power so we managed fine.

Fit the maximum number of watts you reasonably can, but realise that in shaded locations the output will be much less. Try to maximise electrical efficiency as much as possible. This makes a significant difference. Back ups such as propane/diesel cooking provide redundancy, but also mean there are options if cruising in areas with poor solar insolation.

 

[Stemar]

Jissel had two 20w panels on the hatch garage, not the best location, as one or other will be shaded by the boom much of the time, but it was the only convenient place. They were enough to keep up with our modest requirements at anchor in the summer, and recharge the batteries after a weekend aboard in winter, ready for the next weekend. Similar setup on Jazzcat, and for the same reason. I'd like an arch over the stern, but the budget doesn't run to it. Jazzcat has a bigger hatch garage, so she has a pair of 100w panels, which seem to be keeping up with our fridge on sunny summer days, but not dull, cloudy ones.

 

[noelex]

Our previous yacht had 330 w of solar and we were self sufficient in areas of between good and poor solar insolation including running a watermaker. But this was with no electric cooking or water heating. Before that our cruising yacht (in the very early days of solar panels) had 45w, eventually upgraded to 75w. Once again we were self sufficient with no other charging sources, but this was with minimal electrical demands (no fridge or freezer etc).

So we have managed comfortably with a wide range of solar array sizes from 1000w to 45w. These results show you can design a system to work well with a wide range of power inputs.

The main thing is to design a realistic system and manage expectations. We do meet some cruisers who don’t manage well. They have to run generators or plug into shore power and often curse these limitations. This is not limited to those with small solar panel arrays. It is natural to desire luxuries such as electric cooking, but make sure your system is adequate before ripping out the propane.

It’s not what you have, it’s how you use it .

 

[geem]

Our previous yacht had 330 w of solar and we were self sufficient in areas of between good and poor solar insolation including running a watermaker. But this was with no electric cooking or water heating. Before that our cruising yacht (in the very early days of solar panels) had 45w, eventually upgraded to 75w. Once again we were self sufficient with no other charging sources, but this was with minimal electrical demands (no fridge or freezer etc).

So we have managed comfortably with a wide range of solar array sizes from 1000w to 45w. These results show you can design a system to work well with a wide range of power inputs.

The main thing is to design a realistic system and manage expectations. We do meet some cruisers who don’t manage well. They have to run generators or plug into shore power and often curse these limitations. This is not limited to those with small solar panel arrays. It is natural to desire luxuries such as electric cooking, but make sure your system is adequate before ripping out the propane.

It’s not what you have, it’s how you use it .

Agreed. We really can't add any more solar easily, although I may consider bifacial panels when we are back in the UK next year. We still use propane to cook when we don't have enough spare power to cook electrically. Our boat came with a Perkins generator. I don't think I would install one if we didn't have one but if you have one, it's a preferable way to generate 220v for immersion heaters, battery charging and running the watermaker if we don't have sufficient solar available. I do have a 3.7kw alternator ready to fit on the engine but I haven't got around to it as we haven't found the need for it

 

[Refueler]

Swap to lithium batteries and you will get an instant leg up in solar performance. In my experience about a 50% increase in daily solar harvest

I am trying to understand what you are saying .... and whether physics actually agrees. But maybe you've designed a Perpetual Motion Machine ?

And later statement :

I was really pointing out that 440w of solar effectively becomes 660w once you are using lithium.

Energy for nothing ?? I'll have some of that !!

Surely a panel gives what it gives based on sun / hours ... battery charges up to designed voltage / capacity.

Only area I can think can even approach your statement is in resistance to charge ... so in reality there's no increase in amount - just an increase in rate going into the batterys ?

 

[Stemar]

I took it to mean that Li batteries can take a higher charging current, especially once the batteries are nearing full charge, so they're more likely to absorb the full output of the panels,

 

[Refueler]

I took it to mean that Li batteries can take a higher charging current, especially once the batteries are nearing full charge, so they're more likely to absorb the full output of the panels,

Actually that's what I assumed he meant and why I said about resistance to charge, so batts charge up quicker ... but to say 440W = 660W is just ludicrous.

You cannot as they say 'Put a Quart into a Pint pot' .....

 

[Kelpie]

Actually that's what I assumed he meant and why I said about resistance to charge, so batts charge up quicker ... but to say 440W = 660W is just ludicrous.

You cannot as they say 'Put a Quart into a Pint pot' .....

In practice, you run out of daylight hours when trying to charge lead acid batteries from solar. The much higher charge rate of lithium means that every watt of solar actually produces a watt of charging power.
Geem is using a rough approximation to get the, valid, point across

 

[lustyd]

Actually that's what I assumed he meant and why I said about resistance to charge, so batts charge up quicker ... but to say 440W = 660W is just ludicrous.

You cannot as they say 'Put a Quart into a Pint pot' .....

Not all the charge goes to the batteries, and usually the batteries won’t hit full. Anecdotally I’d say he was right we definitely get better yield with the new lithium house battery than we did with lead so whether the number is accurate or not you do seem to get more usable power per watt of panel (or per square metre of deck space)

 

[geem]

Actually that's what I assumed he meant and why I said about resistance to charge, so batts charge up quicker ... but to say 440W = 660W is just ludicrous.

You cannot as they say 'Put a Quart into a Pint pot' .....

What I am saying is that with lead acid batteries our daily solar harvest was circa 2kwh. That same solar capacity now hooked up to a lithium battery harvests 3.5kwh. Same solar but effectively more capacity since the solar never goes of bulk charge. You don't sit there for half the day on float

 

[Refueler]

What I am saying is that with lead acid batteries our daily solar harvest was circa 2kwh. That same solar capacity now hooked up to a lithium battery harvests 3.5kwh. Same solar but effectively more capacity since the solar never goes of bulk charge. You don't sit there for half the day on float

Good ... explained. As I said - resistance related. Stemar caught on as well ...

But many who are not so genn'd up on batterys may misunderstand, think they really get 660W for 440W ....

 

[Refueler]

deleted ... not worth the effort ...