How much solar do you have?

[Pete7]

590w of solar on a 31ft yacht with full electric cooking. Brilliant in June when we had superb clear skies and high pressure across southern England for some weeks. Now away again and with a more typical English climate we are switching in the DC>DC charger occasionally, in fact 4 times in seven days so far. Wasn't strictly necessary but we were motoring anyway so why not have a hour of charging just to be safe.

We have recently installed an analogue kW counter to the inverter output to get a feel for how much we use for cooking each day. However, the numbers are all over the place between 0.5 to 1.2kWh depending on weather or if we are bashing to windward so minimal real cooking, compared to being sat in harbour doing stuff like baking cakes, using the washing machine or running the second fridge.

However, all quite manageable so far and we enjoy cooking on sunshine.

Pete

 

[Kelpie]

590w of solar AND a washing machine... on a 31ft boat... that's quite impressive.

 

[geem]

590w of solar AND a washing machine... on a 31ft boat... that's quite impressive.

Our peak solar is 32A @24v so 64A in 12v money on 920w of solar. Pretty happy with that. Today we have harvested 4kwh from the solar

 

[Neeves]

You need redundancy as it is impossible to have a large solar display on a yacht without part of the display not being at the optimum angle and/or in shade. This is the big problem on a catamaran - enormous area of saloon roof (perfect for flexible panels) except part of the roof will be shaded by the boom, mast (and sails if you are sailing), the flexible panels are more expensive than solid panels and do not have the longevity. Hence roving panels

Compromises, compromises

Jonathan

 

[Kelpie]

Our peak solar is 32A @24v so 64A in 12v money on 920w of solar. Pretty happy with that. Today we have harvested 4kwh from the solar

The only way I can easily measure my output is at the battery monitor, so I'm seeing net input. Typically this peaks at about 50A/12v, for a 930w array.
Generally there will be some loads running (the fridge is quite hungry, at around 6A) so maybe the real figure is closer to 60A.
Another factor is that the panels are distributed around the boat- two are forward of the mast- and see different levels of shading through the day.
Also, most of them were secondhand (how else do you build an entire lithium+solar system from scratch for £1k) so maybe they've degraded a little.
And maybe some of my connections need looked at.
But I'm not overly concerned- despite using almost 100% electric cooking and zero engine charging, I'm still hitting full batteries by 3pm at the latest every day.

 

[Neeves]

The only way I can easily measure my output is at the battery monitor, so I'm seeing net input. Typically this peaks at about 50A/12v, for a 930w array.
Generally there will be some loads running (the fridge is quite hungry, at around 6A) so maybe the real figure is closer to 60A.
Another factor is that the panels are distributed around the boat- two are forward of the mast- and see different levels of shading through the day.
Also, most of them were secondhand (how else do you build an entire lithium+solar system from scratch for £1k) so maybe they've degraded a little.
And maybe some of my connections need looked at.
But I'm not overly concerned- despite using almost 100% electric cooking and zero engine charging, I'm still hitting full batteries by 3pm at the latest every day.

Our peak solar is 32A @24v so 64A in 12v money on 920w of solar. Pretty happy with that. Today we have harvested 4kwh from the solar

You both have big arrays what would be interesting would be a 'better' description of how you achieved that area, so where are the panels located, and how much of the area sees full sun at any one time. I hate to suggest that my masthead picture of Josepheline indicates where our display is located and you can see the obvious shadows - as you may not want to be bothered with an unnecessary climb up the mast (and have a better idea).

Solar in association with Lithium is becoming an increasingly popular thread and one of the big challenges is 'where' to locate the solar. Bimini is probably the foundation but where else....(such that is does not obstruct working the yacht). I understand stanchion attachment is one solution, with fold down panels, but how does that work (at anchor and at sea).

Jonathan

 

[Kelpie]

@Neeves I did describe it at the start of the thread, but to recap:
Rigid bimini comprising 2x260w and 2x100w panels (the inner 100w panels feed the lead acid)
Guardrail mounted 2x100w
Foredeck mounted 2x200w

If stopped for a few days I'll generally swing the boom out to one side to reduce shading. And occasionally I'll play around with the angle on the guardrail panels, although it's barely worth the effort in these latitudes.

 

[Pete7]

590w of solar AND a washing machine... on a 31ft boat... that's quite impressive.

I got so fed up of trying to find launderettes or waiting for the machines in a marina we took a gamble on one of these plastic things. Plus we are trying to use expensive marinas less often. Reviews weren't great of any portable machines, but I recon the break even point is about 20 washes, we are up to about a dozen so far. Quite impressed really, lighter than the little Honda outboard so easy enough to lift in and out of the cockpit locker and very quiet in use. No problem sitting next to it in the cockpit and having a normal conversation, can't do that at home.

Our other power hog is the second fridge/freezer. We have just finished munching our way through enough food to revert back to one, after I went a bit OTT on a shopping trip. Finally we use a 240v air pump for inflating the dinghy rather than faff around with the foot pump. Makes life much easier.

I think one of the problems is mission creep. You can do all the maths you like to try and work out how much solar you need, only to then add another item like a freezer and the numbers go out of the window.

We did pick up a 180w semi flexible panel before we left, but its hopeless generating a maximum of 85w in full sun so that is going back to Amazon and we will do something else. Another 200 - 300w would be nice and ought to be achievable. I don't see a problem of using the guardrails at sea or at anchor, but having to raft up becomes risky even folded down.

 

[Neeves]

@Neeves I did describe it at the start of the thread, but to recap:
Rigid bimini comprising 2x260w and 2x100w panels (the inner 100w panels feed the lead acid)
Guardrail mounted 2x100w
Foredeck mounted 2x200w

If stopped for a few days I'll generally swing the boom out to one side to reduce shading. And occasionally I'll play around with the angle on the guardrail panels, although it's barely worth the effort in these latitudes.

I do read all the posts, unlike some, if the topic is of interest - and I'm contributing. However with a number of overlapping threads (nothing wrong with that) - I do sometimes forget who posted on which. My comment, above, was addressed to you and Geem, but I was a actually referring to 'everyone'.

I did wonder if your, and Geem's, location did mean you were in a 'more ideal latitude' than most for solar - which you imply is correct. Conversely I'm checking a folding panel in a less than idea location (as winter has just finished here). As an aside - ts the first time I have found a phone camera 'better' than a real one. Just snap a pic of the monitor and I have all the data, time and date all conveniently recorded and accessible.

I'm particularly interested on lifeline/stanchion locations as I've never seen anyone doing it, but lots of words on forum - and framed solar are not light.

Its been said before but we are lucky that some with amps under their belt are willing to share their experiences, good and bad. Solar has always been a feature, especially for those of us living in those 'good' latitudes, and Lithium has put a whole new complexion on the opportunities. Like 'GPS' where developments took decades to plateau out - we are at the bottom of a steep learning slope with 'lithium and other alternative storage' technologies. Anyone like us, with slowly developing plans on solar/wind/hydro and lithium have a magnificent resource here - if they are willing to use the search function.

Jonathan

 

[lustyd]

Just snap a pic of the monitor and I have all the data, time and date all conveniently recorded and accessible.

Another advantage of Victron kit is their free online monitoring platform VRM. At the most basic you can use a Raspberry Pi 3 with their Venus OS and it’ll record real-time info 24x7 and upload when the network switches on. I later upgraded to the Cerbo as the hardware is more suitable. Makes it much easier to see what’s going on, so I only need photos of the trip

 

[geem]

I got so fed up of trying to find launderettes or waiting for the machines in a marina we took a gamble on one of these plastic things. Plus we are trying to use expensive marinas less often. Reviews weren't great of any portable machines, but I recon the break even point is about 20 washes, we are up to about a dozen so far. Quite impressed really, lighter than the little Honda outboard so easy enough to lift in and out of the cockpit locker and very quiet in use. No problem sitting next to it in the cockpit and having a normal conversation, can't do that at home.

Our other power hog is the second fridge/freezer. We have just finished munching our way through enough food to revert back to one, after I went a bit OTT on a shopping trip. Finally we use a 240v air pump for inflating the dinghy rather than faff around with the foot pump. Makes life much easier.

I think one of the problems is mission creep. You can do all the maths you like to try and work out how much solar you need, only to then add another item like a freezer and the numbers go out of the window.

We did pick up a 180w semi flexible panel before we left, but its hopeless generating a maximum of 85w in full sun so that is going back to Amazon and we will do something else. Another 200 - 300w would be nice and ought to be achievable. I don't see a problem of using the guardrails at sea or at anchor, but having to raft up becomes risky even folded down.

We have 4x50w Renogy panels mounted on a piece of canvass. When not using them they fold up in to the size of a single panels and we store it on the front bunk. In use, we deploy it on the sun cover or if we aren't using the over boom suncover, we place it on the foredeck. They normally give us an additional 500wh a day. I can split it down to 2x100w panels. I haven't tried it yet, but 100w will fit on the sprayhood. This is all in addition to 4x180w mounted on the guardrails.
We haven't had a problem rafting up with panels on the guardrails, but we use big fenders. And we have a set of 4 Avon hyperlon fenders as an addition that allow us to protect the panels a little more.

 

[Graham_Wright]

As an addendum, I have two panels 50W each whcih are connected to a Victron controller by a selector switch. This can select port, starboard, parallel and series.
It is interesting to compare series and parallel either of which can produce the best charge rates depending on something I can't determine.

 

[Kelpie]

I'm particularly interested on lifeline/stanchion locations as I've never seen anyone doing it, but lots of words on forum - and framed solar are not light.

It's pretty common here in the Caribbean.
I've seen all manner of methods, including fancy mounting frames, friction clamps, etc.
But simple works too. These panels are not all that heavy- about 7kg for a 100w rigid. If your guardrails cannot support that 7kg supported between two points a metre apart, then I would not want to rely on them to keep people onboard, or even to tie fenders to.
My initial setup simply used a bulldog clamp as a u-bolt, through two holes drilled in the panel frame, to hold it on to the wire. I had a convenient high point to attach a bit of string to hold the panel up.
Later, as part of creating the bimini, I added a steel tube in parallel with the top guardwire, and now the panels hang from there. I just made U-bolts from some threaded rod I had.

I've never had any worries when rafting up. Probably depends on the design of the boat. We're old enough to narrow a bit at the stern, so the panels don't actually come anywhere near your neighbour. We're also pretty high out of the water.
And even if a panel did get damaged, I wouldn't lose too much sleep over it. They're one of the cheapest things on the boat so I'd actually much rather somebody hit a panel than just about anywhere else.

 

[Neeves]

I was not worried about the strength of the stanchions more the load of the panel, 7kg stuck out as a lever, and how to support, or you support, in, say, chop.

Thanks, answer understood. I had assumed a strut at an angle off the toe rail but you are hanging them from 'something' above

Jonathan

 

[geem]

I was not worried about the strength of the stanchions more the load of the panel, 7kg stuck out as a lever, and how to support, or you support, in, say, chop.

Thanks, answer understood. I had assumed a strut at an angle off the toe rail but you are hanging them from 'something' above

Jonathan

We do ours like this

 

[Kelpie]

I was not worried about the strength of the stanchions more the load of the panel, 7kg stuck out as a lever, and how to support, or you support, in, say, chop.

Thanks, answer understood. I had assumed a strut at an angle off the toe rail but you are hanging them from 'something' above

Jonathan

A strut is probably a more common method, and removes a source of shading. My ~3mm line doesn't really throw any appreciable shading, although I have had one chafe through and snap in the past.
(No harm done, by the way. Rigid panels are surprisingly robust).

 

[doug748]

10 W with a 100Ah battery. Works great on a small boat. Can't imagine wanting more for typical, summer UK boating.

 

[geem]

10 W with a 100Ah battery. Works great on a small boat. Can't imagine wanting more for typical, summer UK boating.

I guess no fridge then

 

[B27]

Many people use the engine enough to power a fridge and just use a panel to top up or float charge between outings.
With an efficient fridge and a few hours motoring, you can get a lot out of a 100Ah battery.
More so with a boosted alternator.
It's the way it used to be, except now, fridges can use less power.

If you are only on board a few dozen nights a year, then being kind to the battery to get thousands of cycles out of it is less important.
Many people use the motor a few hours in a typical day of their summer cruise.
And if once a year they have to turn off the fridge because the battery is getting low, life goes on!

Not everyone needs their boat to be like a house connected to the National Grid.

 

[geem]

Many people use the engine enough to power a fridge and just use a panel to top up or float charge between outings.
With an efficient fridge and a few hours motoring, you can get a lot out of a 100Ah battery.
More so with a boosted alternator.
It's the way it used to be, except now, fridges can use less power.

If you are only on board a few dozen nights a year, then being kind to the battery to get thousands of cycles out of it is less important.
Many people use the motor a few hours in a typical day of their summer cruise.
And if once a year they have to turn off the fridge because the battery is getting low, life goes on!

Not everyone needs their boat to be like a house connected to the National Grid.

We have had a fridge on all 3 of our boats over the last 20 odd years. They all had solar. Never needed the engine to charge.
I think we have more power than the National grid