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Solar panel setup


blackrose

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Just because a boat has a big roof doesn't mean the owner wants to clutter it up completely with solar panels.

 

Anyway, I don't think I need 3kW of solar. No point over-specifying if it's not required but perhaps I should get 4 of those panels instead of two? That's 700w.

 

 

 

 

Edited by blackrose
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Red

44 minutes ago, blackrose said:

Just because a boat has a big roof doesn't mean the owner wants to clutter it up completely with solar panels.

 

Anyway, I don't think I need 3kW of solar. No point over-specifying if it's not required but perhaps I should get 4 of those panels instead of two? That's 700w.

 

By my calculations at an average of 4 hours peak sun hours/day in summer I'd get about 80 ah/day from 4 of those panels. That would have to do.

 

 

Depends what you are going to do, if it's in a marina, you can cover the lot, if you are going to venture outside in summer you need to have room to allow you to walk about on roof if you do that kind of thing at locks. You don't want to interfere with the centre line (s).

There is also the cost of the little swing brackets, which can be expensive, if you have two panels and a matching controller it should not be too expensive, and will be ok six months, if you later decide to have three panels, or four, you may need another controller or a bigger one, which might be justified if you use boat as cc, but if marina based , ie shorepower, again that is a different game, expect electricity prices to rise!

PS there are YouTube vlogs, notably Pacific Yacht Systems who discuss capacity and such like. I like three to five days autonomy with my batteries, as I want them to last a long time. If the weather is cloudy and you are not charging the batteries it's surprising how they lose charge.. My ancient fridge hammers mine, so I only use it to chill my beer!

Edited by LadyG
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Work out where you want to put them on the roof, measure the size then get the largest panels you can to fit the space. I have just under 500w of panels and a 40amp Epever controller and it's only just enough to keep the boat running for 8 months of the year. In your case I would be looking at 4 panels of 250-300W  each wired in series/parallel. One thing to do is not to get panels designed for 12v systems as their voltage will not be high enough in low light to generate decent power, you need a panel that has an Voc of about 40v, the controller will deal with it and reduce it to the required charge voltage.  I am on the boat for a couple of days if you want to have a look/chat.

Edited by Loddon
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8 minutes ago, Loddon said:

One thing to do is not to get panels designed for 12v systems as their voltage will not be high enough in low light to generate decent power, you need a panel that has an Voc of about 40v, the controller will deal with it and reduce it to the required charge voltage.

 

 

AGREED.

 

I went for 120v panels so I get  'muliple' times the panel current output into my batteries depending on voltage.

 

1amp out of the panels can mean  7 amps going into the batteries.

 

With only 92 volts , 0.5a out of the panel = 3.3a into the (almost fully charged) batteries

 

 

 

 

18-2-18.jpg

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1 hour ago, LadyG said:

Red

Depends what you are going to do, if it's in a marina, you can cover the lot, if you are going to venture outside in summer you need to have room to allow you to walk about on roof if you do that kind of thing at locks. You don't want to interfere with the centre line (s).

There is also the cost of the little swing brackets, which can be expensive, if you have two panels and a matching controller it should not be too expensive, and will be ok six months, if you later decide to have three panels, or four, you may need another controller or a bigger one, which might be justified if you use boat as cc, but if marina based , ie shorepower, again that is a different game, expect electricity prices to rise!

PS there are YouTube vlogs, notably Pacific Yacht Systems who discuss capacity and such like. I like three to five days autonomy with my batteries, as I want them to last a long time. If the weather is cloudy and you are not charging the batteries it's surprising how they lose charge.. My ancient fridge hammers mine, so I only use it to chill my beer!

 

There will be plenty of room on the roof to walk even if I have 4 of those panels. I'm not having swing brackets, the panels will be in a fixed position on the roof using the bumble plastic corner brackets even if that means they're less efficient. The panels won't interfere with my centre lines as I have two running through fairleads down each side of the boat. 

 

54 minutes ago, Loddon said:

Work out where you want to put them on the roof, measure the size then get the largest panels you can to fit the space. I have just under 500w of panels and a 40amp Epever controller and it's only just enough to keep the boat running for 8 months of the year. In your case I would be looking at 4 panels of 250-300W  each wired in series/parallel. One thing to do is not to get panels designed for 12v systems as their voltage will not be high enough in low light to generate decent power, you need a panel that has an Voc of about 40v, the controller will deal with it and reduce it to the required charge voltage.  I am on the boat for a couple of days if you want to have a look/chat.

 

Ok thanks that's interesting. Don't get panels designed for 12v systems. This is exactly the sort of information I need to know. I'll try to get down to see you tomorrow or Tuesday. I'll send you a text. 

Edited by blackrose
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I have recently bought a 'kit' from Bimble and Laura was very helpful. My kit does not look quite like any of the kits you would find on their website as it includes the things I needed, does not include the things I didn't need, but still has equivalent pricing to the kits they usually sell, ie it was cheaper than if I had priced up the components individually. They definitely answer the phone and know what they are talking about.

 

I ended up going for CIGS as I wanted the panel to be virtually invisible, but ours is not a liveaboard so for me it's more about keeping batteries topped up at our unserviced mooring.

 

Alec

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  • 2 weeks later...
On 12/06/2022 at 23:21, agg221 said:

I have recently bought a 'kit' from Bimble and Laura was very helpful. My kit does not look quite like any of the kits you would find on their website as it includes the things I needed, does not include the things I didn't need, but still has equivalent pricing to the kits they usually sell, ie it was cheaper than if I had priced up the components individually. They definitely answer the phone and know what they are talking about.

 

 

My experience differs. Laura didn't really answer my question about higher voltage panels and said forums are full of irrelevant information.

 

So who do I believe; knowledgeable forum members some of whom I've known for years, do know their stuff and have no agenda other than trying to help, or someone I don't know who's main objective is to sell me the panels that they have in stock? I'll go elsewhere. 

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On 12/06/2022 at 15:35, David Mack said:

Tracer controllers (and maybe others) will take an input of up to double the rated output without damage (but won't deliver more than the rated output), so you could reduce the controller output (and cost), which will reduce the peak power available at the height of the summer, but will extend that output further into the autumn and spring.

I’m trying to get my head around that. 
It might answer what I’ve been trying to work out. 
 

When you say rated input and output, are you talking Amps?


 

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Just now, Goliath said:

I’m trying to get my head around that. 
It might answer what I’ve been trying to work out. 
 

When you say rated input and output, are you talking Amps?


 

Simplistically, a controller rated at 20 Amps will deliver a maximum of 240 W at 12 volts. So you could couple it with a 240 W panel and it could in theory put out 20 Amps in optimum summer conditions. But in spring and autumn the same panel might only output 120W which would appear as 10 Amps at the controller output.

Now put two identical 240 W panels into the same controller and in spring and autumn you will get 20 Amps out. And in the summer the controller will cope with the full input of 480 W of panels without damage, but still put out the 20 Amps rated maximum.

So at tge height of summer you get the same output to your batteries, but you have extended the period over which you get that maximum.

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4 minutes ago, David Mack said:

Simplistically, a controller rated at 20 Amps will deliver a maximum of 240 W at 12 volts. So you could couple it with a 240 W panel and it could in theory put out 20 Amps in optimum summer conditions. But in spring and autumn the same panel might only output 120W which would appear as 10 Amps at the controller output.

Now put two identical 240 W panels into the same controller and in spring and autumn you will get 20 Amps out. And in the summer the controller will cope with the full input of 480 W of panels without damage, but still put out the 20 Amps rated maximum.

So at tge height of summer you get the same output to your batteries, but you have extended the period over which you get that maximum.

Great 👍 

That is what I have been pondering. 
 

I have  a 200W panel and a 20A Mttp controller. 

So I can double up my panels and not f*** up the controller if I should ever  have a perfect sunshine day producing a theoretical max of 28A through the panels because the controller will cope (if it’s a decent one) and convert it to whatever. 

 

 

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1 hour ago, Goliath said:

Great 👍 

That is what I have been pondering. 
 

I have  a 200W panel and a 20A Mttp controller. 

So I can double up my panels and not f*** up the controller if I should ever  have a perfect sunshine day producing a theoretical max of 28A through the panels because the controller will cope (if it’s a decent one) and convert it to whatever. 

 

 

I assume it will con be set the excess in to heat via the heat sink vanes on the reverse?

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8 hours ago, LadyG said:

I assume it will con be set the excess in to heat via the heat sink vanes on the reverse?

Sorry not sure what happened there, I meant to say, I assume excess energy converts to heat and the vanes on the controller are there to disperse this heat.

Edited by LadyG
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1 hour ago, LadyG said:

Sorry not sure what happened there, I meant to say, I assume excess energy converts to heat and the vanes on the controller are there to disperse this heat.

That's not how MPPT controllers work. The cooling fins are just there to dissipate the heat from the internal switching circuits which convert the incoming panel high voltage/low current to outgoing battery low voltage/high current, this heat loss is typically about 5% of the total power in a good controller (95% efficiency). The controller adjusts the incoming voltage/current to maximise the power from the panels, hence MPPT.

 

If the controller wants to reduce the power into the batteries it will just raise the incoming voltage higher which reduces panel power; if it goes all the way to the panel open-circuit voltage then the power drops to zero. Lower power throughput means less dissipation in the controller so the cooling fins get less hot.

 

Alternatively if the batteries are full the controller can just shut down completely.

Edited by IanD
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Bimble came back to me on the question of higher voltage panels. This is what they said:

 

A panels power is ALL that matters.

The general voltage x amps = power is all that matters.

Higher voltage panels produce lower amps.

When a charge controller drops the voltage it increases the amps.

An fantasy example (with easier Maths!)

A - 120w panel is 120volts and 1a.... through a charge controller on a 12v battery drops to 12volts and 10a... same power - 120w
B - 120w panel is 240volts and 0.5a.... through a charge controller on a 12v battery drops to 12volts and 10a... same power - 120w

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On 21/06/2022 at 19:41, blackrose said:

 

My experience differs. Laura didn't really answer my question about higher voltage panels and said forums are full of irrelevant information.

 

So who do I believe; knowledgeable forum members some of whom I've known for years, do know their stuff and have no agenda other than trying to help, or someone I don't know who's main objective is to sell me the panels that they have in stock? I'll go elsewhere. 

I think you'll find all solar companies main objective is to sell you the panels they have in stock, or can deliver by drop shipping. Bimble use a dedicated courier, I found their advice and delivery excellent. They had several different panels, I just went with a standard kit for my boat, no issues.

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1 hour ago, LadyG said:

I think you'll find all solar companies main objective is to sell you the panels they have in stock, or can deliver by drop shipping. Bimble use a dedicated courier, I found their advice and delivery excellent. They had several different panels, I just went with a standard kit for my boat, no issues.

 

Yes I know all solar panel retailers main objective is to sell you the panels that they have in stock. I think you'll find that was my point. 

 

What's the courier got to do with anything?

 

You may have found their advice excellent, but my experience differs from yours. 

Edited by blackrose
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6 minutes ago, blackrose said:

 

Yes I know all solar panel retailers main objective is to sell you the panels that they have in stock. I think you'll find that was my point. 

 

What's the courier got to do with anything?

 

You may have found their advice excellent, but my experience differs from yours. 

The panels are large and fragile, use any old delivery and there will be problems, I assume that is why Bimble use one man and his van., He put them on my roof, rather than leaving me to struggle. They may have other couriers for those who live in distant parts, but my guy indicated he did their deliveries full time.

 

Edited by LadyG
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1 hour ago, LadyG said:

 

Ok great, but since I'm not buying my panels from Bimble the delivery driver and his van is irrelevant. Any supplier is responsible for shipment of the goods they supply and the condition they arrive in. If they arrive faulty or damaged the supplier arranges collection and return. How or who panels are delivered by may be a criterion you use to decide where to buy panels from, but it's not a big deal for me. 

Edited by blackrose
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On 21/06/2022 at 19:41, blackrose said:

 

My experience differs. Laura didn't really answer my question about higher voltage panels and said forums are full of irrelevant information.

 

So who do I believe; knowledgeable forum members some of whom I've known for years, do know their stuff and have no agenda other than trying to help, or someone I don't know who's main objective is to sell me the panels that they have in stock? I'll go elsewhere. 

I suspect whether you have a satisfactory experience depends on what you are looking for, ie our respective experiences are not mutually exclusive because we have different criteria.

 

My impression from your posts is that you are looking for some rather detailed information of the sort which would require someone to be a technical expert in solar panels. This appears not to be a service offered by Bimble to the level which you are looking for.

 

I on the other hand didn't need any detailed technical information. I have a particular area available on my roof, I wanted an inconspicuous panel to go on it to keep the batteries topped up and I needed all the bits to connect the panel to the batteries. Bimble were able to define what I needed to achieve that, tell me what my options were with associated pros and cons at a basic level and then sell me the parts as a 'kit' at a decent price and get them delivered by a means which ensured they arrived intact and ready to use, rather than having the hassle of inspecting them and arranging to have them replaced.

 

Therefore I was a satisfied customer.

 

Alec

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Apologies if this is repetition, but I havent time to read all the posts, so just a quick note regarding the expected 'ampage' output from your planned setup:

 

I originally had 660 watts in four smaller panels, and I found that there were odd days even in summer when the panels would struggle to replace the charge I'd used each day (main usage being fridge, but laptops, TVs etc are not insignificant). 

The poor days would be when I was moored in places where much of the sky was obscured by trees, or when it was heavily overcast, or of course both. Those days arent common but they will happen, even with 500-600 watts. 

 

I added another 750 watts in early September, and I found that I was then self-sufficient for power (i.e. no need to run the engine for charging) until about mid-Oct. After that things start to decline (as expected), and as November progressed I was increasingly having to run the engine for most/all of the daily charge.

In Dec and Jan I found that the solar input was not really significant at all, unless I was in a location where it was worth tilting the rear panels (and the sun was out), which was maybe every three or four days. I did talk to a guy who was a low power user and was self sufficient almost throughout winter, but he was moored full time in an open spot, with his panels facing almost due south, and he had them tilted up to about 60 degrees so they caught even the very low sun, with two panels hanging on the side of the boat- but we cant all replicate his circumstances, or even want to. 

 

The reverse progression happened as Spring approached. If memory serves, I was getting significant solar by mid-Feb on some days, and by early March it was doing most of the charging on most of the days, and I think since mid-March I've barely used the engine specifically for charging. 

 

I do have lithium batteries though- if you have lead acids, you might find they dont charge quite as well during the marginal months.  

I was also doing some tilting on odd days (if the sun was out and the side of the boat was facing south), so that will have improved my charging a little. 

For comparison- since early Sept, my front panels (not tilted) have yielded 210kWh, and the rear set (sometimes tilted) have given 242kWh. 

 

ETA- if you only move say once a week or so, having 1000 watts or more of panels mean you can use the excess charge to heat the immersion, and thus save running the engine.

I've had hot water (hot enough to wash anyway) on almost every day since around mid-April, and that will have been a significant saving given the price of diesel. 

The extra panels will eventually pay for themselves in various ways, e.g. reduced engine wear, less frequent servicing, etc. 

 

 

Edited by Tony1
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1 hour ago, agg221 said:

My impression from your posts is that you are looking for some rather detailed information of the sort which would require someone to be a technical expert in solar panels. This appears not to be a service offered by Bimble to the level which you are looking for.

My impression is that he's looking for some rather basic info on the difference the panel voltage makes to the expected output in various, but particularly low light conditions. I agree with him that this basic element of panel choice is rarely if ever discussed and I also wonder why that is.

 

Maybe it's because it actually doesn't make much difference apart from high voltage/low amp panels not requiring such beefy cabling as low volt/high amp panels. If that's the case you could infer that the higher the output, the more gain to be had from high volt/low amp panels in terms of less bulky/expensive cables and losses in the cables.*

 

*I'm armchair at this, a grownup will be along to clarify hopefully.

Edited by Slow and Steady
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17 minutes ago, Slow and Steady said:

Maybe it's because it actually doesn't make much difference

 

 

Or maybe it is not recognised that (say) a 100 volt panel only getting enough sun to produce 50% of its output - 50 volts, so allowing the MPPT to utilise it to charge a 12v battery.

 

My 120 volt panel is often producing 20 volts, 50 volts, 75 volts etc etc

 

Even as low as 15.5 volts it can still put a litttle (0.3 amps) into the battery - they do not always put out their rated voltage

 

2-9-20.jpg

 

 

A 19 volt panel only getting the same sunlight (50%) will produce 9.5 volts that the MPPT cannot use to charge a 12v battery.

 

This is why it is beneficial, if you have low voltage panels, to wire them in series - 2x 19v panels in series = 38v which in the above poor light (50%) conditions will still produce 19v which the MPPT can use to charge the battery.

Edited by Alan de Enfield
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3 minutes ago, Alan de Enfield said:

 

 

Or maybe it is not recognised that (say) a 100 volt panel only getting enough sun to produce 50% of its output - 50 volts, so allowing the MPPT to utilise it to charge a 12v battery.

 

My 120 volt panel is often producing 20 volts, 50 volts, 75 volts etc etc

 

Even as low as 15.5 volts it can still put a litttle (0.3 amps) into the battery - they do not always put out their rated voltage

 

2-9-20.jpg

 

 

A 19 volt panel only getting the same sunlight (50%) will produce 9.5 volts that the MPPT cannot use to charge a 12v battery.

 

This is why it is beneficial, if you have low voltage panels, to wire them in series - 2x 19v panels in series = 38v which in the above poor light (50%) conditions will still produce 19v which the MPPT can use to charge the battery.

Good answer! 

So... higher voltage panels for the win? Are their any downsides that you're aware of?

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