Are high wattage solar panels worth the hastle...

[Ukiyo]

You can presently get really quie high wattage solar panels for a great price.

The trouble is that this means more amps get pulled though the solar controller and high amp solar comtrollers are expensive.

 

At what point is it worth buying a larger panel?

 

Freya

[Phil Ambrose]

Freya only you can decide how much in terms of watts you need. I for example use quite a lot because I run a full size 12v fridge and a full size 12v freezer (under counter models) other people do likewise plus things like dishwashers. I do not rely on solar for my washing machine and my tumble dryer, preferring to run a Genny at such time.

What sort of wattage are you talking about?

Phil

[MtB]

I find this a most peculiarly worded question...

 

It's not a proper question at all really, as it's impossible to answer in any meaningful way.

[GoodGurl]

I find this a most peculiarly worded question...

 

It's not a proper question at all really, as it's impossible to answer in any meaningful way.

basically what he is saying is this : if he buys 1KW of solar the controller/s will be expensive, but if he only buy's 250w of solar the controller will be cheaper, so will he get his money's worth with a dearer outlay.

[Loafer]

At the point that you decide you don't have enough solar power.

 

Fill your cabin top space with them, then buy an MPPT controller that can handle the current.

 

Whatever the cost, it'll save you petrol, diesel, engine wear & tear, noise, fumes, irritation, arse, long walks to petrol garages, storage of dangerous fluids etc.

 

That's if you live on a boat. If not, disregard the above. 2p

[WotEver]

basically what he is saying is this : if he buys 1KW of solar the controller/s will be expensive, but if he only buy's 250w of solar the controller will be cheaper, so will he get his money's worth with a dearer outlay.

 

How can anyone other than the OP possibly answer that?

[Ukiyo]

basically what he is saying is this : if he buys 1KW of solar the controller/s will be expensive, but if he only buy's 250w of solar the controller will be cheaper, so will he get his money's worth with a dearer outlay.

Yes that's exactly right, well other than the "he" bit anyway..

[George94]

It's a perfectly sensible question.

 

The answer is that if you have the space, it may make more sense to go for less efficient panels if the price per watt is lower than the high output panels.

 

If you don't have the space, you don't have the choice.

 

As a rule of thumb, go for high output on a narrowboat, but do the sums if you have a widebeam or a barge.

 

ETA: By price per watt, I mean the total price, including controller.

Edited December 11, 2015 by George94

[WotEver]

Surely the decision is simply "How much solar do I need?" Which is another way of saying "How much power do I require?"

 

Only the OP can answer that question.

[Ukiyo]

 

How can anyone other than the OP possibly answer that?

I can understand what you are saying but OTH I've already had some great answers.

 

At the moment I have a tiny set up (about 20-30 watts) and I have been getting by but it's always nice to have more!

 

I guess there are various points at which you have to decide if its worth the step up to a vastly more expensive controller or settle for less panels.

[Loafer]

Well for my 2p I'd say get more. 20-30W is known in the trade as 'bugger all'!

 

You could make do with a simple PWM controller from eBay, plus a 100W panel or two.

 

30A 12V/24V Solar Controller Regulator Charge Battery Safe Protect CE Certify SP

 

That'll cope with up to about 390W of panels.

[Ukiyo]

Surely the decision is simply "How much solar do I need?" Which is another way of saying "How much power do I require?"

 

Only the OP can answer that question.

I can definitely understand that way of looking at things and it is quite traditional but I find that in practice, for me at least, it's always about having to make a compromise. You are never going to have enough power for the kind of things that might be normal on mains power. However each step up might allow you to do something more. I guess that's why it's called power.

 

As a lot of people have pointed out there is also the physical aspect which is something I need to think about more.

[George94]

Everybody's needs vary, obviously, but I find that my 440 Watt panels normally provide enough power by themsleves from April to September for everything but the washing machine. To run the washing machine I would have had to increase the number of panels, the number of batteries, and the controller. Definitely not worth it.

 

So for me, the sweet spot is a minimum of 400 Watts of panels. For more frugal people it might be 300, and for more lavish it might be 1,000.

 

But, it's DEFINITELY worth having enough solar to satisfy your everyday needs between late Spring and early Autumn. It's cheaper, less hassle, quieter, more reliable, and longer lasting, than any other off-grid power source.

 

And go for MPPT. It maximises the output, which is very important on a day with variable levels of sunshine.

 

ETA: I cook with gas and boil water on the stove. I don't use electrical gadgets in the kitchen, or hair-dryers, or a TV. But I do have an inverter, and use it to charge phones and power tools, and to run the vacuum cleaner. The radio gets lots of use, as does the laptop.

Edited December 11, 2015 by George94

[Ukiyo]

Well for my 2p I'd say get more. 20-30W is known in the trade as 'bugger all'!

 

You could make do with a simple PWM controller from eBay, plus a 100W panel or two.

 

30A 12V/24V Solar Controller Regulator Charge Battery Safe Protect CE Certify SP

 

That'll cope with up to about 390W of panels.

We'll these Chinese controllers aren't really PWM they are basically fake. However they do work as basic controllers and 30 amp is very cool for the price (assuming it can really do that) . At the moment I have a Morningstar controller which really is PWM but is only 10 amps. Still that does give me scope to expand a little and keep the same controller.

 

This does open up the question of whether its worth ditching PWM and just getting a really cheap Chinese controller with plenty of amps.

[George94]

UKiyo, if you live on the boat and don't have mains, then get a propr solar system. It'll pay for itself in just a few (sunny) months.

 

Bimble is your friend.

[Chewbacka]

To answer the question original question, what do you want the solar to do?

If it is just to keep the batteries topped up, even in winter a smallish panel will keep the batteries in good nick whilst you leave the boat for weeks at a time, so probably no more is required.

 

If you want to be able to moor up for a day or three without running the engine at all you will need a lot more than you have, I get by with 400w in summer.

In winter you would probably want a small field full of panels to ensure no engine running what ever the weather.

 

A bit more than you currently have, may still mean running the engine everyday, so no real gain.

 

So what do you want the panels to do? Then work out how much power you will need.

[Ukiyo]

I have to say some of this stuff is kind of mind blowing for me. Dish washers, freezers, even considering a washing machine is just wow!

 

Is anyone here running a microwave?

 

I can run my little DVD player and watch movies, charge my nook/phone, listen to my DAB radio. Run an LED lamp and it's almost enough to charge my tiny laptop. It feels like luxury!

 

Freya

[WotEver]

We'll these Chinese controllers aren't really PWM they are basically fake.

I'm not sure that's true. Certainly some of the cheap MPPT controllers from China don't appear to do very much at all but PWM is simple enough technology to get right.

 

Tony

[Ukiyo]

UKiyo, if you live on the boat and don't have mains, then get a propr solar system. It'll pay for itself in just a few (sunny) months.

 

Bimble is your friend.

 

George your posts have all been interesting and really helpful. Bimble do have panels at a great price so I'm going to definitely have to think about maybe upgrading my Morningstar for more amps or getting a very cheap Chinese controller or something.

Edited December 11, 2015 by Ukiyo

[Ukiyo]

I'm not sure that's true. Certainly some of the cheap MPPT controllers from China don't appear to do very much at all but PWM is simple enough technology to get right.

Tony

I know what you mean but the PWM controllers are also fake. It's really bizzare because they have gone to a lot of trouble to make them seem real and you would think by that point they might as well just have made a real PWM controller.

 

Most of the chinese controllers are basically the same electronics in different cases. They say PWM or MPPT and cost different prices but inside it is the same stuff. Just a switching controller. Having said that if you get a really cheap chinese controller that can handle a lot of amps they can be great value.

[MtB]

I can definitely understand that way of looking at things and it is quite traditional but I find that in practice, for me at least, it's always about having to make a compromise. You are never going to have enough power for the kind of things that might be normal on mains power. However each step up might allow you to do something more. I guess that's why it's called power.

 

 

This bit troubles me.

 

Solar panels do not "allow you to do something more", they allow you to run your engine or genny less, to recharge your batteries. They are a battery charging device rather than a power supply to run equipment directly. Consider them a silent genny or alternator.

 

Further, a solar panel will vary widely in its output with the weather. A 80 Watt (say) panel only delivers its maximum 7 Amp output when the sun is shining and high in the sky. On a bleak dull winter's afternoon it might only deliver 3% of that 7 Amps. So they are effectively useless in winter for battery charging unless you have masses of them, in which case you have far more than you need in summer!

 

My set of 4 x 80 panels is, for example, charging my batteries at 0.6 Amps right now. On a sunny summer day it might charge at 15 Amps typically.

Edited December 11, 2015 by Mike the Boilerman

[Loafer]

The PWM controllers aren't fake. They're the simple ones, and very cheap, and do work well for the price. It's the cheap MPPT controllers which are fake, mostly. A good MPPT controller can give up to 30% more power from the same panels.

[Alan de Enfield]

I know what you mean but the PWM controllers are also fake. It's really bizzare because they have gone to a lot of trouble to make them seem real and you would think by that point they might as well just have made a real PWM controller.

 

Most of the chinese controllers are basically the same electronics in different cases. They say PWM or MPPT and cost different prices but inside it is the same stuff. Just a switching controller. Having said that if you get a really cheap chinese controller that can handle a lot of amps they can be great value.

 

Hi Freya - you seem to have some knowledge on ins-and-outs of MWP & MPPT controllers (or is it just something you have been told ?)

With you having this knowledge I find it strange that you are struggling with the concept of what Solar can do, and can provide for you.

 

As has been said your 12v 'power' requirements are ALL met by your batteries.

You can put the power into the batteries in different ways - but all are considered 'battery chargers'

1) Running the engine - the alternator is a battery charger

2) Plugging into a landline and running a battery charger

3) Running a generator and powering a battery charger

4) Putting 12v directly into your battery straight from solar panels via a controller.

 

All methods of battery charging 'cost' (primarily either petrol or diesel) although plugging into the mains (landline) is without doubt the cheapest.

 

Once the initial 'capital expenditure' of the solar system ( you could get a good system from Bimble for £500 ish) has been paid the electricity is 'free'

 

The 'capital expenditure' for a generator is similar ( or higher) than Solar, and, you have the ongoing costs of (around) £1 per hour to run it.

 

We can live comfortably ( 12v Fridge on 24/7, unlimited TV, phone charging, PC charging, lighting, occasional twin-tub washing machine, water pumps etc) in the Summer with 200 watts. In fact, the SOC of the batteries ( 2 x 135Ah) when we got up in the morning was higher than when we went to bed.

We could moor up for at least 3 days without running the engine - probably longer if I really wanted to.

Just as an aside - I believe that an MPPT controller will give round 30% more 'power' than a MWP controller.

The controller may cost more, but, its worth it for the 'extra' that actually gets put into your batteries

[Phil Ambrose]

I can understand what you are saying but OTH I've already had some great answers.

 

At the moment I have a tiny set up (about 20-30 watts) and I have been getting by but it's always nice to have more!

 

I guess there are various points at which you have to decide if its worth the step up to a vastly more expensive controller or settle for less panels.

Hmm, I have a 20 watt panel just dedicated to maintaining my starter battery, my 300 watt main PV array feeds into my domestic bank.

Have you done a power audit, what size is your domestic bank, do you live aboard? all pertinent questions if you are to get a useful response.

Phil

[Phil Ambrose]

I have to say some of this stuff is kind of mind blowing for me. Dish washers, freezers, even considering a washing machine is just wow!

 

Is anyone here running a microwave?

 

I can run my little DVD player and watch movies, charge my nook/phone, listen to my DAB radio. Run an LED lamp and it's almost enough to charge my tiny laptop. It feels like luxury!

 

Freya

Freya, I've said this so many times, living on a boat does not mean camping.

Phil