Another solar related question.

[Anseo]

I will eventually go down the road of fitting solar panels, probably 150w roof mounted, but I have a lot to learn before taking the plunge.

So I thought it would be easier for my simple mind to gain information a few steps at a time.

Fridge and cooker and heating will be from gas.
I think that only leaves, 12v TV, lights (LED) and water pump(s).

Will I be able to run 12v TV (8 hours a day - my wife watches a lot of TV and videos particularly if weather is inclement , and run lights and pumps for up to a week on solar alone?

TIA

 

[WoodlandsCamper]

Fridge and cooker and heating will be from gas.
I think that only leaves, 12v TV, lights (LED) and water pump(s).

If you have a modern van then fridge and heating will have a control panel operating on 12v.
You may also have a 12v operated toilet flush (don't use the flush so often ).
Radios also have a constant 12v feed even when switched off.
Besides the TV itself there is normally an aerial booster working off 12v.

A solar panel may be able to keep up with everything, but I don't have one to verify it.

 

[ProfJohnL]

Fridge and cooker and heating will be from gas.
I think that only leaves, 12v TV, lights (LED) and water pump(s).

If you have a modern van then fridge and heating will have a control panel operating on 12v.
You may also have a 12v operated toilet flush (don't use the flush so often ).
Radios also have a constant 12v feed even when switched off.
Besides the TV itself there is normally an aerial booster working off 12v.

A solar panel may be able to keep up with everything, but I don't have one to verify it.

How modern caravans have sprouted equipment that seems to need a constant 12V supply to just enable them to run even if the 12V is not the main fuel souse it uses. hmy:

It is generally the case that a 50W (4.6Apeak or avearge 2.5A) panel would is enough to keep most caravan batteries healthy even when off grid, BUT its the 8 hours of TV and media usage that might tip the scales here. Most modern television used in caravans will be rated around the 40W power mark, That equates to 3.33A continuous power usage.. I would guess that a media player will use about 1 A, so that is 4.3Amps Over 8 hours that is 35Amp hours or approximately 30% of a 110Ah batteries capacity.

In theory a 150W solar panel should produce a peak current of 12.5A at 12V under optimum conditions. However you only get anything approaching optimum for a few hours a day, and off course nothing at night, so in practice its more likely to be an average closer to 12.5A x 60% = about 7.5A.

So if a 50W panel is good for most caravanners and it has an average current delivery of about 2.5A and you need a further 4.3 for your media usage that is 6.8A per daylight hour average recharge capacity, which teh 150W panel should manage with a little to spare.

There are a lot of assumptions made here, and where possible I have erred on the cautious side so I suspect your proposal should work for you.

 

[Anseo]

Sir WC,

The van is a 2013 Bailey Pegasus Ancona GT65

If modern van then fridge and heating will have a control panel operating on 12v. Correct
You may also have a 12v operated toilet flush . Correct
Radios also have a constant 12v feed even when switched off. Did not know that - Correct
Besides the TV itself there is normally an aerial booster working off 12v Correct

You have reminded me that I will be using even more power via the radio speakers, I route the TV sound output through the radio console.

Prof,
Thank you for your calculations and comments, appreciated.

Encouraging responses so far, and a helpful starter.

 

[Anseo]

May I ask for advice on another aspect of solar panels folks.

This time it is controllers:

As I understand we have MPPT and PWM controllers, MPPT claims approx 30% efficiencyperformance over WPM.

But, if say I opted for a 200w WPM panel as against a 150w MPPT (the price difference is considerable), would this make sense as a purchase option.

My reasoning being that the greater outer output of the 200w panel may somewhat negate the benefits of of a 150w MPPT; the approx 50% cost difference does very much come into play in this (for me).

May I have your views folks ?

 

[Martin24]

I'm not going to get involved with the nuts and bolts technical side, all beyond a simple chap like me.

We used to have a 55w free standing panel that was used all year around. We never had a shortage of battery life once. All lights LED is the main thing but winter long weekends and rallies were always fine however gloomy the day and we'd use it for weeks on end in the summer with no issues what so ever.

Okay so we only had an hour or so at the most with the television on each day.

Now we have a 100w roof mounted, just so no extra setting up on arrival.

 

[Parksy]

May I ask for advice on another aspect of solar panels folks.

This time it is controllers:

As I understand we have MPPT and PWM controllers, MPPT claims approx 30% efficiencyperformance over WPM.

But, if say I opted for a 200w WPM panel as against a 150w MPPT (the price difference is considerable), would this make sense as a purchase option.

My reasoning being that the greater outer output of the 200w panel may somewhat negate the benefits of of a 150w MPPT; the approx 50% cost difference does very much come into play in this (for me).

May I have your views folks ?

Hi Anseo
Did you mean that you are trying to decide between a 150 watt Maximum Power Point Tracking controller and a 200 watt Pulse Width Modulation controller?
Or do the different wattages apply to a choice of solar Panels?
In the case of solar controllers, sometimes also known as regulators, the wattage that is shown refers to what it can safely handle, not the output which comes from the panel.
This means that if the maximum output of your solar panel is 200 watts then whichever solar regulator (controller) that you buy has to be capable of safely regulating 200 watts.
MPPT controllers are more efficient than PWM models, but they are more expensive as you have seen. Don't be misled by the word 'tracking'.
The regulator actually 'tracks' the charge level of your leisure battery and allows any excess voltage to be converted to amps to pass to the battery depending on how much charge the battery needs. The MPPT controller will allow constant trickle charging.
The power output of your solar panel is therefore controlled (or regulated) for optimum charging efficiency.
A Pulse Width Modulator controller (sometimes known as a Shunt controller) is a bit like an on / off switch.
Power is fed to the leisure battery at a set rate until a certain charge level is reached, and then the controller 'shunts' (or switches off the power) until the charge drops below a certain level, then it's on full blast again.

Click Here to read about the differences between the two systems written by somebody much brighter than I am.
Personally speaking, if budgetary considerations are an issue I'd opt for an inexpensive PWM controller to see how solar power works for your own requirements.
If you decide that solar is the future for you, there's time to save up and replace the cheapo PWM with a more expensive and better engineered MPPT system.
You might decide that the PWM does a good enough job (I did, my £15 version has been doing it's job for years) and alternate between off ehu solar powered weekend rallies and sites with ehu (electric hook up)

 

[Anseo]

Parksy,

Sorry that I am not explaining my meaning well (trying to get my head round the whole solar thing before making any purchase decisions, and hoping to get it right first time).

I hope the following explains my question better:

Say I buy a kit that has a 140 watt panel with an MPPT controller ( http://www.sunstore.co.uk/140w-12v-MPPT-Solar-Battery-Charger-Vehicle-Kit.html ) at around £400.00.

Or I buy a kit that has a 200 watt panel with a PWM controller ( http://www.alpha-batteries.co.uk/solar-panels/12v-200w-xplorer-german-cell-solar-panel-kit-for-caravans-boats-motorhomes/ ) at £230.00.

I'm wondering if the cheaper option would work as well (or nearly as well) as the more expensive option given the larger panel sizewattage on the cheaper setup.

Perhaps (likely) my logic is flawed in making such a comparison

 

[Anseo]

I am now pondering over another aspect of solar power :blink:

Would it be better to invest in a second battery, and if I did, what sizewattage of solar panel would be recommended to provide battery top up charge.

I havecan make room to connect a second battery to the one stored in the battery locker, only downside I can see is the not insignificant extra weight and of course the cost.

If I went this route, would I need a different type of controller that would supply top up charge to each battery, I am assuming that both batteries could be permanently linked together.

TIA for any help on my questions.

 

[Parksy]

I see what you meant now
It's a no brainer my friend, go for the 200 watt solar panel without a doubt!
The advertising blurb on the more expensive panel is all very well but seriously, do you really need to: 'add a remote meter to monitor the power that is being generated as well as monitoring your battery condition and state.'
There's a very good chance that both panels will have been made in China and imported, so the £200 cost difference is hard to justify.
We're talking about a caravan here, not a massive system to power your home so micro monitoring wouldn't be necessary.
A 200 watt solar panel should keep your leisure battery topped up for you to use during the summer months and should deliver enough charge during the winter to power your alarm system provided that the panel is not in the shade or covered in snow, leaves or mildew.
It would be a simple task to replace the supplied PWM controller at any stage if you wanted to, either system will do the job but you only get out what is put in. 200 watts trumps 140 watts every time. There are plenty of 200 watt solar systems with MPPT controllers for less than £300.
Have a look on Fleabay, this one has caravan roof mounting brackets but there are slightly less expensive panels without the brackets

 

[Parksy]

I am now pondering over another aspect of solar power :blink:

Would it be better to invest in a second battery, and if I did, what sizewattage of solar panel would be recommended to provide battery top up charge.

I havecan make room to connect a second battery to the one stored in the battery locker, only downside I can see is the not insignificant extra weight and of course the cost.

If I went this route, would I need a different type of controller that would supply top up charge to each battery, I am assuming that both batteries could be permanently linked together.

TIA for any help on my questions.

You'd have to connect the batteries in parallel if you connected them at all because caravan systems run on 12 volt and if you wired the batteries in series you'd end up with a 24 volt system that would destroy your 12v electrics.
Taking your previous questions into consideration I'm not sure that it would be a good idea for you to try to somehow 'connect' two 12v leisure batteries.
Two connected batteries wouldn't deliver twice as much power either because if one is more discharged than the other the better battery charges the poorer battery instead of delivering the stored power to your systems.
On long trips off ehu I take two 12v 120 amp/ hour leisure batteries and connect one after the other if there is not enough solar charge available, but one battery ought to be ok for a long weekend, and in summer months a solar charged battery in good condition can last almost indefinitely with careful use of 12v systems and led lighting.

 

[Anseo]

Thanks Parksy, that is just the the kind of insight that I am looking for.

I will go for the largest panelwattage I can fit (within costreason) and I shall use a PWM controller.

Cheers (if there was a 'thumbs up' emogi I would have used it )

 

[Anseo]

Parksy,

Re your battery related reply.

Points taken, I like the spare battery idea, and it can be kept in the car and saves weight in the caravan.

At what state of charge on the connected battery do you replace it with the spare battery ?

I assume you remove the discharged battery from it's housing and replace with spare battery, or is there another method that you use ?

Thanks for your helpful replies, I feel that I am becoming more comfortable on the solar options available

 

[Martin24]

Don't forget if you're adding a large solar panel and an extra battery you'll be carrying quite a bit of extra weight.

 

[Parksy]

Yes, I keep the spare in the car and when the lights start to go a bit dim and the tv won't work from the inverter I change over by removing the discharged battery from the compartment and physically replacing it.
For a quick work-a-round in poor weather when no solar charge is available I drive to an isolated spot (e.g. a lay by), connect the vehicle jump leads to the discharged battery from the car battery and charge the leisure battery from the car alternator without disturbing anyone. It only took about ten minutes using my old Pajero, but that's being sold this weekend and I haven't tried it using the Kia Sorento tow car.

 

[Anseo]

Don't forget if you're adding a large solar panel and an extra battery you'll be carrying quite a bit of extra weight.

I guess I will go with Parksy's suggestion of keeping a spare battery in the car, I will have to make sacrifices elsewhere to allow for the extra weight on the roof.

Being caught up in the solar mist I did forget about potential weight issues , thanks for the reminder Martin.

 

[ProfJohnL]

Hello Anseo,

I suspect you may be over complicating the answer to your problem. Referring back to my quick calculation, I suspect you will more than enough capacity with a the 150W panel a simple controller, and a 110Ah battery.

A second battery is a another possibility, but then how do you charge it, and as has already been mentioned it adds weight and it must be secured and stowed properly in an acid proof container ventilated to the outside. It may seem a lot of work and expense for little reward.

Whats the worst that could happen? :huh: (perhaps i'm opening an can of worms here hmy: but) you may have to curtail the television hours a bit. :blink: You may have to relearn the art of conversation over some liquid refreshment!" :cheer: Or discover the delights of arguing if "ix" is a allowed in Scrabble. :evil:

 

[Anseo]

Yes Prof, I most probably am over complicating things, but that is down to my lack of understanding of the matter

All the points you make are most relevant.

As for less TV and conversation over a dram or two (Mrs Anseo does not imbibe - so I will have her dram ), it is certainly not an armageddon scenario should the lights go dim :lol:

Cheers.

 

[Anseo]

Just to add to the mix, my present battery is 85Ah, going by the advice already received I guess I should uprate to 115Ah.

I see that Halfords have http://www.halfords.com/camping-leisure/caravan-motorhomes/electrical-power/halfords-leisure-battery-115-ah

Or are there better options out there ? cost V performance V warranty etc.

 

[ProfJohnL]

I seem to recall PC magazine did do a comparison of batteries, but I can't put my hand on it at the moment.

As for your current (no pun intended 85Ah battery if its still in good condition it will probably work for you with the 150W panel its just a question of how big the reservoir of power is so for example a really dull day you may use say 30% of the charge in a 110Ah battery where as it will be nearer 45%of an 85Ah battery, but it would have to be almost dark or the solar panel covered up for that scenario to be a major concern.

I'd suggest try the 85Ah and if it dosen't cut the mustard then upgrade.

 

[Bwlch]

If you do need to upgrade your battery your current one will make a good spare to keep in the car as suggested by Parksy.

 

[Anseo]

I now have some spondoolies to spare for a solar panel set-up.

Before I make the final choice, I was wondering if you kind folks might suggest a better way for me to to part with my spondoolies (it's a bit like parting with blood to a haggis) other than this offering:

http://www.alpha-batteries.co.uk/solar-panels/12v-200w-xplorer-german-cell-solar-panel-kit-for-caravans-boats-motorhomes/
Thanks,
Anseo

 

[Martin24]

200w ? What are you running? a caravan or stately home? We've always managed with 100w roof mounted and before that 55w free standing. No problems with either and never ran out of juice whatever the weather or time of year.

 

[ProfJohnL]

Haggis and whisky

 

[Anseo]

I just had an 'online' chat with the company that I was thinking of buying the kit from.

I asked if there were fitting instructions for the kit, the reply was "we dont have fitting instructions sorry".

Before I could ask if any special adhesives or sealants were required, they disengaged the chat without any notice.

I know it is not rocket science, but I am now a bit reluctant to purchase without fitting instructions.

Bit disappointed really.

Anseo