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My Spanking New Solar Project


tictag
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My spanking new solar project

Hello fellow ‘leccy geeks,

I’ve been working through the design for a new electrical energy system for my ‘van and I would welcome your input. My high level requirements are:

  1. ‘van has solar off grid
  2. ‘van has 230v mains off grid
  3. Leisure battery is charged optimally i. e. as quickly as safely possible
  4. Mains supply automatically switches between EHU / genset (Hyundai HY3000SEI)
  5. EHU supply is supported when loads exceed site circuit breaker
  6. Inverted mains does not supply Alde heating system
  7. Solar solution capacity balanced between summer and winter caravanning (based on 50AH per day usage)
  8. All relevant electrical regulations are strictly adhered to
  9. Implementation has zero effect on ‘van warranty

So find my solution attached and described below:

system schematic - overall system schematic

  • Victron multiplus inverter accepts one mains input and, when connected, supplies both ac out and inv out. If the mains supply is lost (or never there) supplies inverted mains to inv out only i. e. alde heating never powered by battery.
  • Multiplus has 6-stage 50A battery smart charger, operational when mains supply is available
  • All caravan mains circuits are RCD protected – inverter neutral tied to battery return & chassis.
  • Genset connected via new standard blue socket (fixed fitting)
  • Ve. net panel displays all standard battery usage data (e. g. AH remaining, current etc), can be used to configure the inverter and has output to PC for data analysis
  • Multiplus has programmable relay that I hope will allow me to automatically start the genset on low battery voltage

solar physical – physical layout of the solar solution

  • 6 x flexible 100W panels provides around 42AH per day during winter – not enough to cover usage but a design balance to ensure generator is used optimally and panel voltage can be split equally
  • Panels positioned to maximise summer (roof) and winter (side) sun
  • MPPT controller used to maximise efficiency for British weather and winter caravanning
  • Large combined cable (6mm2) to minimise losses to controller and onwards to battery
  • Existing TV antenna used as entry point if possible, if not, sealed roof entry gland used.

solar schematic – electrical diagram of panel connections

  • Panels wired half in series to increase voltage without increasing current, minimising heat effect losses then in parallel to stay within system voltage specification of MPPT controller i. e. 75vdc

I haven’t worked out the full cost yet but it’s likely to be in the order of £2,500. All work will be carried out by me and certified by a qualified electrician (my brother!).


sml_gallery_63455_1385_70615.jpg sml_gallery_63455_1385_8836.jpg sml_gallery_63455_1385_27807.jpg

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Nice plan, and pretty much what I am about to do this year, only difference being I will be relying far more on solar and less on a genset or indeed hookup.

 

What power output is the inverter you are considering ?

 

Looking at your diagram though you have 2 banks of 3 panels wired in series, so panel output is only going to be 200watt, personally I would have banked the panels as groups of two an extra 5amps output,

 

Just need to source a decent ups and I will be using a 400ah minimum battery bank, I just need to monitor weight although we travel light and payload is 225kg, 100kg of batteries will still leave us more than enough for our essentials.

 

Good luck with it sounds promising

Edited by Mike&deb
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Thank you :)

 

DC power output is always volts x current, irrespective of how they are wired. In this case, the series connected panels increase the voltage without increasing the current (like adding batteries in series i. e. 23vdc + 23vdc + 23vdc = 69vdc x 5adc = 345W - note the voltage figures are open circuit, not under load), the parallel connected sets will supply more current but maintain the same voltage (like parallel banks of batteries i. e. 5adc + 5adc = 10adc x 70vdc = 700W - again, I won't get this power output because the voltage figures are open circuit figures but this is needed to avoid exceeding the system voltage specification of the MPPT controller, which is 75vdc)

 

I've been thinking about battery capacity too. Currently discussing two-deep battery compartments in the Ring inverter thread (hmmm, now that I think about it, that sounds off topic!)

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Tictag - can re-name you HarryMk2 ? :)

Graham

Unless otherwise stated all posts are my personal opinion 

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Just need to source a decent ups and I will be using a 400ah minimum battery bank, I just need to monitor weight although we travel light and payload is 225kg, 100kg of batteries will still leave us more than enough for our essentials.

btw, if money is no object and weight is more important, you could consider a lithium battery bank? More expensive than rocking horse poo but a lot lighter (70% compared to Lead Acid). Victron do a range here: http://www. victronenergy. com/batteries/lithium-battery-12,8v/

 

You're looking at about £100 per AH. Yes, that isn't a typo.

Edited by tictag
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btw, if money is no object and weight is more important, you could consider a lithium battery bank? More expensive than rocking horse poo but a lot lighter (70% compared to Lead Acid). Victron do a range here: http://www. victronenergy. com/batteries/lithium-battery-12,8v/

 

You're looking at about £100 per AH. Yes, that isn't a typo.

Yes, I have seen them as well if only money was no object lol

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What power output is the inverter you are considering ?

Got your edit. I'm pluming for 1,800W with a peek surge output of 3,000W. My biggest load is my 800W microwave, rated at 1,200W with 2,400W surge, add a bit more for other connected items e. g. laptop and Victron's 1,800W unit fitted the bill. The larger units (3,000W & 5,000W) are a bigger and heavier units so wern't a good design choice for a caravan.

 

Tictag - can re-name you HarryMk2 ? :)

I am not worthy of such an honour! ;)

Edited by tictag
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Heeey! Got my forth star! Happy days are here again, the sky above is clear again. ...

:D

p. s. It's the little things you have to focus on when you suffer with depression!

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Looking at your diagram though you have 2 banks of 3 panels wired in series, so panel output is only going to be 200watt, personally I would have banked the panels as groups of two an extra 5amps output,

 

 

With an MPPT controller the higher the voltage, the better it is providing it's within the voltage rating of the controller.

 

Ap

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With an MPPT controller the higher the voltage, the better it is providing it's within the voltage rating of the controller.

 

Ap

Yes I am aware of that, but in my opinion I would rather have panels that are wired in series in pairs, voltage would still be high enough for a MPPT controller to work, as the ones I have looked at recommend a voltage of only 36volts,

 

This in my opinion would better as if a panel goes open circuit then that is 3 panels not producing power, whereas if panels were in pairs then there would only be 2 panels not producing and would leave 4.

 

As I say it is only my opinion I will climb back into my cave now ^_^

Edited by Mike&deb
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Forget lithium.

I have been using them for several years now in my RC model aircraft.

Models vary from sub one ounce all up weight to 5 foot wingspan scale aerobatic machines with 1+ plus HP motors.

All using LiPos.

Yes they are much lighter than lead acid and nicads.

Yes they have come on phenomenally in the 4 years I have been using them.

From 1C to 5C charge rates!!

Sadly they are just not safe for recreational caravans.

When short circuited-by damage or vandalism they will ignite-you could say explode.

Similarly they cannot be trusted in multiple cell configurations for ordinary users as they are prone to unbalancing IE weak cells.

A potentially lethal problem since it gives rise to overcharging and the dreaded thermal run away.

For model aircraft the almost magic power to weight ratios coupled with recharge rates from flat to ready to fly-in under 20 minutes means LiPos are the up and coming new kid on the block.

All my aircraft and helicopters are electric.

The to date unsolved problem with LiPos is they are a chemical fire just waiting to be lit!

Once ignited they will burn till all their fuel is exhausted.

They contain all the components needed to completely incinerate the battery and it seems the full size aircraft containing them!

Certainly they have burned out cars trucks boats and houses to date.

The fire cannot be extinguished using any known techniques since like phosphorus it just keeps burning!

I am always VERY careful with mine.

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Tictag unless the controller has a remote sensor try to keep it as close to the battery as reasonably possible

Paul B

. .......Mondeo Estate & Elddis Avanté 505 (Tobago)

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Yes I am aware of that, but in my opinion I would rather have panels that are wired in series in pairs, voltage would still be high enough for a MPPT controller to work, as the ones I have looked at recommend a voltage of only 36volts,

 

This in my opinion would better as if a panel goes open circuit then that is 3 panels not producing power, whereas if panels were in pairs then there would only be 2 panels not producing and would leave 4.

 

As I say it is only my opinion I will climb back into my cave now ^_^

All interesting stuff BUT with all of the panels in series, battery charging will start at much lower light levels, furthermore, most if not all panels are made up of series and parallel connected cells so the likelihood of a panel going open circuit is very small.

 

Ap

Forget lithium.

 

I have been using them for several years now in my RC model aircraft.

Models vary from sub one ounce all up weight to 5 foot wingspan scale aerobatic machines with 1+ plus HP motors.

All using LiPos.

Yes they are much lighter than lead acid and nicads.

Yes they have come on phenomenally in the 4 years I have been using them.

From 1C to 5C charge rates!!

Sadly they are just not safe for recreational caravans.

When short circuited-by damage or vandalism they will ignite-you could say explode.

Similarly they cannot be trusted in multiple cell configurations for ordinary users as they are prone to unbalancing IE weak cells.

A potentially lethal problem since it gives rise to overcharging and the dreaded thermal run away.

For model aircraft the almost magic power to weight ratios coupled with recharge rates from flat to ready to fly-in under 20 minutes means LiPos are the up and coming new kid on the block.

All my aircraft and helicopters are electric.

The to date unsolved problem with LiPos is they are a chemical fire just waiting to be lit!

Once ignited they will burn till all their fuel is exhausted.

They contain all the components needed to completely incinerate the battery and it seems the full size aircraft containing them!

Certainly they have burned out cars trucks boats and houses to date.

The fire cannot be extinguished using any known techniques since like phosphorus it just keeps burning!

I am always VERY careful with mine.

Hi Ancell,

You're talking about LiPoly here, there is of course Li-Ion that could be considered, widely used in power tools, safe, good power to weight etc etc.

 

Ap

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I think you will find that it was Li-ion cells that destroyed an aircraft recently.

 

They are used in power tools but they use industrial encapsulation and dedicated chargers IE designed for a one off encapsulated "brick".

 

You will notice these industrial cells are not chargeable without the dedicated charger.

 

Even the "fast charge" power tools are deliberately limited to low charge rates typically 30 minutes to 45 minutes.

 

I can "push" some LiPos to charge fully in 10 minutes!

 

Just google Dell and Apple Li-ion safety issues with heat dissipation-that's polite for overheating and combustion.

 

It will make you think twice about building that into your caravan

 

Mobile phones use single cell lithium batteries this obviates most of the risk BUT there have been mobile phone generated residential fires.

Not things to be left charging overnight or when you are not at home :)

 

In my opinion-and the fire brigades :D

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Well I haven't experienced any fires with Li-Ion, considering the huge number in use eg laptops, tablets, power tools, cameras, phones the list is endless, I think that's good. Anywhere that energy is stored is capable of starting a fire, of all of the batteries, Li-Ion is one of the safer ones.

 

Ap

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Well I haven't experienced any fires with Li-Ion, considering the huge number in use eg laptops, tablets, power tools, cameras, phones the list is endless, I think that's good. Anywhere that energy is stored is capable of starting a fire, of all of the batteries, Li-Ion is one of the safer ones.

 

Ap

Personally never experienced it, but it does and has happened

 

http://www. pcworld. com/article/126735/article. html

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I can "push" some LiPos to charge fully in 10 minutes!

 

 

In actual fact you can't, maybe 90% but you have not a hope in hell of 100% in 10 minutes, even attempting this would a) damage the cells, B) shorten the life of them and c) reduce the capacity. I regularly use 5c rated cells and I do charge at 5c, the theoretical charge time of course is 12 minutes, the final 10% or so takes 20 minutes or thereabouts to get in.

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In actual fact you can't, maybe 90% but you have not a hope in hell of 100% in 10 minutes, even attempting this would a) damage the cells, B) shorten the life of them and c) reduce the capacity. I regularly use 5c rated cells and I do charge at 5c, the theoretical charge time of course is 12 minutes, the final 10% or so takes 20 minutes or thereabouts to get in.

Where is b ) :D

Edited by Mike&deb
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Very true, just like explosions with gasses given off with lead acid batteries. What sort of batteries are used on hybrids like the Prius?

 

Ap

There was no mention of hybrids, just " laptops, tablets, power tools, cameras, phones",,, doubt it will be long before we hear of overheating Prius's but not due to mechanical faults :-(

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Charging from "flat" to fully charged in 10 minutes.

 

I meant "real world flat"

 

That is no more aerobatic performance.

 

The Battery Eliminator Controller will cut power to the motor before the battery is "flat" so you can still safely get the aircraft landed under proper control.

 

LiPo and lithium batteries in general do not like full discharge hence most devices have built in cut outs to avoid low voltages.

 

In my experience 10% of my batteries will be lost per annum due to fast charging and low voltage due I suspect to matching issues between cells IE one cell being drained below safe minimum.

 

My batteries cost between £4 and £20 so dud batteries just get scrapped unlike a caravan battery.

 

However a caravan li-ion battery is £700!

 

http://www. ebay. co. uk/itm/12v-100AH-LITHIUM-ION-DEEP-CYCLE-BATTERY-CARAVAN-4WD-MARINE-SOLAR-3-YR-WARRANTY-/300778833960

 

You will notice it weighs 17 kilos!!

 

You will have to buy the charger for it to :)

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Yes I am aware of that, but in my opinion I would rather have panels that are wired in series in pairs, voltage would still be high enough for a MPPT controller to work, as the ones I have looked at recommend a voltage of only 36volts,

 

This in my opinion would better as if a panel goes open circuit then that is 3 panels not producing power, whereas if panels were in pairs then there would only be 2 panels not producing and would leave 4.

 

As I say it is only my opinion I will climb back into my cave now ^_^

 

Why not just have the panels in parallel :unsure:

 

Each panel will produce from 17 to 30+ volts depending on make, if one fails then you lose only one,

and a good genuine MPPT controller is designed to adjusts the voltage and amperage automatically according to the batterys charge state

Paul B

. .......Mondeo Estate & Elddis Avanté 505 (Tobago)

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The Victron range are Lithium Iron Phosphate and, according to them, the safest of the Lithium Ion chemistry's.

 

Tictag unless the controller has a remote sensor try to keep it as close to the battery as reasonably possible


Yes, good point, I'm mounting it directly behind the battery. Cable run should be less than 50cm.

 

Yes I am aware of that, but in my opinion I would rather have panels that are wired in series in pairs, voltage would still be high enough for a MPPT controller to work, as the ones I have looked at recommend a voltage of only 36volts,

 

Yes, I see your point. I suppose I'm thinking optimistically (maybe naively) in that it's unlikely they would fail (they are flush mounted and built for standing on) and I'd prefer higher voltage than current when it comes to avoiding losses.

 

 

 

Why not just have the panels in parallel :unsure:

 

I figured I would reduce losses by keeping the current flow to a minimum whilst staying within the controllers system voltage specification.

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Why not just have the panels in parallel :unsure:

 

Each panel will produce from 17 to 30+ volts depending on make, if one fails then you lose only one,

and genuine MPPT controller is designed to adjusts the voltage and amperage automatically according to the batterys charge state

in my honest opinion I would personally go for that arrangement, but MPPT do need higher voltages than PWM, hence my reason for 2 in series as a bank to increase the voltage, then to put the banks into parallel.

 

As said it is only my personal opinion and no doubt others will have their way of doing it

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There was no mention of hybrids, just " laptops, tablets, power tools, cameras, phones",,, doubt it will be long before we hear of overheating Prius's but not due to mechanical faults :-(

I'm simply illustrating that LiIon is used successfully in a very demanding application and they don't seem to be catching fire every. 2 minutes.

 

Ap

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