Simple solar setup

[steveG]

Helping my son in law with a simple solar setup on his tradie trailer for a 60L Waeco running as a fridge.
What he's trying to achieve is a setup that will just sit happily and run 24x7 without needing to be plugged into a charger. Its always outside from a solar perspective (ie not garaged over the weekend etc).
Worst case if he's having to plug in the charger over the weekend during winter to get the battery topped up I'm sure he'd cope with that.

So far he's got a 240W panel, and a used 130Ah AGM and 15A charger which I had spare at home and he's using a Morningstar 30A regulator that I loaned him when his $16 cheapie spat the dummy after a couple of weeks.

So, first question (so I can get my regulator back!!) - whats the up to date recommendation for a solid no-frills 30A regulator? A built in voltage display would be nice but not essential.

Secondly, a bit of Googling suggests that the Waeco is likely to consume around 24Ah per day.
I'd expect the panel to supply enough to power the fridge during daylight hours even on poor solar days, but time will tell I guess. Assuming that as a worst case, then he'd only be drawing 12Ah/day from the battery, so a 100Ah one should seem him through the week at around 60% discharge.
Does that sound reasonable?
I'm thinking a battery in the 100-130Ah range would suit - any recommendations on size/type/brand etc?

Steve

[weeds]

umm, 24amp/hrs per 24 hours...........that's 1 amp/hr per hour in a metal clad trailer

i'd reckon it will use more than that.......especially in summer

I use fullriver batteries and victron regulators......these are probably at the other end of the market that your son is chasing

[goingbush]

I have a Waeco 28L in between the front seats of my Iveco, connected to a 100Ah Aux battery under back seat, 5year old chinese eBay 30A MPPT solar charger and a 280watt house panel the roof , Its run 24-7 for 5 years no problems . Im sure they have the same compressor as the 40L .

I have it connected to the Main battery by a Isolator so when the Aux battery is full it keep the main battery topped up. Works a Treat.

[Homestar]

Agree with Weeds, in a enclosed trailer in Summer it will likely use a lot more power - I run my Engel in my Hilux all Summer to keep my lunch and drinks cool and it runs about 60% of the time on a warm day - about twice as much as what it does when outside on a similar day. Not an issue for me as the car does a couple of hundred K's a day but running it off solar you may need a bit more that what you're planning.

I would suck it and see though - you can always add to it - 240 watts of solar and a 120Ah battery or so will be a good start. I too use Fullriver batteries but there are other good ones out there - and there are a lot of crap ones too, so be careful.

A MPPT charger will get 15 to 20% more into the battery per day so worth spending the extra money on one - Victrons are the best IMO, but again, there are others. If you look at ebay regs and it says MPPT but is as cheap as a PWM unit, it won't be a MPPT - there's a lot of BS out there on these too.

[steveG]

Good point about the environment. I hadn't considered that.
I suppose its all just assumption and guesswork without any real data. Maybe I should start with something like this to capture some: KickAss Digital DC Watt Meter for Portable 12V Solar Panels (https://www.australiandirect.com.au/Battery-Systems/Electronics-Appliances/KAMeter1)

Steve

[101RRS]

A MPPT charger will get 15 to 20% more into the battery per day so worth spending the extra money on one

My experience is not quite the same - most MPPT chargers are basically a 3 stage charger and in winter I found there was not enough daylight for the MPPT to go through its full cycle and this resulted in the battery not being fully charged at the end of the day. I put a Dr Watts meter on it and I found the old style straight regulator which just provides charge worked better as it got more charge quicker into the battery before the sun disappeared. Not as good for the battery though.

Not an issue with longer daylight hours in summer where the MPPT worked fine as it had time to go through its full cycle but not in winter.

Though, on the basis of the readings from my Dr Watts meter, there was not a lot of difference in overall charging from the cheap reg my solar panels came with and the MPPT reg I bought.

I am sure the MPPT is better for the long term health of the battery though.

Garry

[DiscoMick]

I have an 80 watt panel on the Defender's roof rack connected to a PWM regulator next to the starting battery which is linked to a 110 amp second battery through a Traxide DBC to run a 30 litre Evakool fridge and it works fine.
Keep in mind the temperature setting on the fridge and how much stuff is in the fridge will make a lot of difference to how frequently the fridge switches on and off. The emptier the fridge the more power it will draw.

[steveG]

I have an 80 watt panel on the Defender's roof rack connected to a PWM regulator next to the starting battery which is linked to a 110 amp second battery through a Traxide DBC to run a 30 litre Evakool fridge and it works fine.
Keep in mind the temperature setting on the fridge and how much stuff is in the fridge will make a lot of difference to how frequently the fridge switches on and off. The emptier the fridge the more power it will draw.

Will that setup run indefinitely on just the solar, or is the battery voltage getting low after a few days if you don't run the engine?

Steve

[roverrescue]

I run two 60W panels (eBay cheapies) in parallel feeding a VictronConnect 75/15 controller to a 130AH AGM running a 40L Engel
It runs indefinitely, battery will always get to second stage and most days will get to float
I honestly just park the Ute in the sun so fridge works hard but solar needs juice!

A few days last week I had a bunch of steel on the rack which zeroed the output but next day full sun and she catches up quickly?

Steve

[roverrescue]

A few screen grabs from the VictronConnect data logger
Can see just 120W of panel makes enough juice as required
Fridge consumption seems to wander around a bit even though it is always generally half full?

Steve

[DiscoMick]

Will that setup run indefinitely on just the solar, or is the battery voltage getting low after a few days if you don't run the engine?

Steve
I can't remember ever having had to recharge the second battery. We have camped for up to a week no problems.
If your tradie son is driving to and from worksites on week days he should have no problems staying charged.
There used to be a solar calculator on the Redarc site which could accept proposed details to give an idea.
Still, more is better with solar.

[Konradical]

I fitted the 110W king's panel and 15amp MPPT controller to my tool box after I had finished using it for the Canning trip.

It charges a 55Ahr Exide battery similar to the D34 Yellow top and runs a 40Lt Engel upright set to just the 1 side of 2.

It's been going since October sometime and the voltage has never dropped below 12.8V.

This fridge is in a steel clad toolbox with no additional ventilation and is in direct sun for better part of the day.

Keeps those bottles and cans of relaxing beverages Icy cold!

[steveG]

Slight sidestep, but anyone have experience with this company or these batteries:
130AH Deep Cycle AGM Battery | Eclipse 12 Volt 130ah Deep Cycle Battery | 130AH AGM Battery (https://www.aussiebatteries.com.au/batteries/deep-cycle-agm/130ah-12v-eclipse-agm-deep-cycle-battery)

Steve

[Homestar]

My experience is not quite the same - most MPPT chargers are basically a 3 stage charger and in winter I found there was not enough daylight for the MPPT to go through its full cycle and this resulted in the battery not being fully charged at the end of the day. I put a Dr Watts meter on it and I found the old style straight regulator which just provides charge worked better as it got more charge quicker into the battery before the sun disappeared. Not as good for the battery though.

Not an issue with longer daylight hours in summer where the MPPT worked fine as it had time to go through its full cycle but not in winter.

Though, on the basis of the readings from my Dr Watts meter, there was not a lot of difference in overall charging from the cheap reg my solar panels came with and the MPPT reg I bought.

I am sure the MPPT is better for the long term health of the battery though.

Garry

Not noticed that issue. My (very rough) calculations when I went from a PWM to MPPT showed nearly 25% at best and around 10% at worst so I averaged it at 15 ish... Found during overcast days and shorter days is when it worked best compared to a PWM to be honest. Only back of the envelope type calculations so not saying they were terribly accurate though.

[weeds]

It's been going since October sometime and the voltage has never dropped below 12.8V.

!

What do the volts drop to overnight

[Konradical]

What do the volts drop to overnightNot 100%

Up north you could hear it cycle twice an hour for about five minutes a cycle, but by the time I got outside to test it, it was generally already charging and sitting around 13.1-13.3V.

Down here, SA, I generally hear it cycle at most once an hour and short 5 minute cycles at that. Haven't had the time to check voltages. It's too cold down here to start drinking in the morning.

(Above is at night)

Il endeavour to get one of those Bluetooth monitors on it and actually watch what it's doing. Who knows, it could drop below what I have stated.

[DiscoMick]

Not 100%

Up north you could hear it cycle twice an hour for about five minutes a cycle, but by the time I got outside to test it, it was generally already charging and sitting around 13.1-13.3V.

Down here, SA, I generally hear it cycle at most once an hour and short 5 minute cycles at that. Haven't had the time to check voltages. It's too cold down here to start drinking in the morning.

(Above is at night)

Il endeavour to get one of those Bluetooth monitors on it and actually watch what it's doing. Who knows, it could drop below what I have stated.12.8 is fully charged (6 x 2.1). Surely it would drop overnight?

[Konradical]

12.8 is fully charged (6 x 2.1). Surely it would drop overnight?It probably does, but I don't know what it drops to.

12.8V was measured with fridge cycling, middle of a 40 degree day up north. That's the lowest I have seen it go.

Like I said, once I get something on it to record overnight voltages I can more accurate in my findings.

[Blknight.aus]

80w on an n55 runs an engel for 3 days starting with the n55 fully charged and winding up with it at nominal flat voltages.

(the old engles will draw down to 6v)

[roverrescue]

If you have a look at the data logs I copied in
The lowest battery min voltage I’m getting is 12.24
Most nights it only drops to 12.4

This is in SEQ Average day temps in 30s (Engel in sun)
Overnights high teens

I really think with a good controller, 100 plus AH battery and 120-180W of panel you’ll be fine

[Aaron IIA]

A 175W panel through a Victron MPPT regulator to a 30AH battery powers my 40L Waeco indefinitely. To get the full benefits of your MPPT regulator, set up your solar panel as 40V rather than 20V.

Aaron

[DiscoMick]

On Straddie for a week at Christmas a 160 watt folding panels kept 2 x 120 amp batteries powering a 65 litre Primus fridge- freezer charged indefinitely in our camper.

[trout1105]

I have a 120w flexible solar panel running through a PWM to an 80ah battery that runs my 38l Engel on the boat 24/7 and it has been doing this for months, The Engel is set at just before "2" on the dial.
I also have a fixed panel 160w on the roof of my Navara running through another PWM to 2x 125ah batteries that run a Primus 40l fridge 24/7 without any issues even in 40c+ temps, I do however have to give the batteries a bit of a chance to catch up with this setup by plugging into 240v if i also run the 80l Waco as a freezer as well.
If I added my 160w foldout panel to the Navara setup I wouldn't have to use 240v at all[thumbsupbig]

[trout1105]

I have a couple of spare MPPT solar controllers wired up with anderson plugs (just in case) in my toolbox.
Are these MPPT controllers more efficiant/better for the batteries than the PWM controllers I have on my boat and truck?

[DiscoMick]

As I understand it, PWMs just limit the maximum charge to a set amount, but MPPTs may allow more in some circumstances. But I'm sure an expert will correct that if necessary.

[bee utey]

As I understand it, PWMs just limit the maximum charge to a set amount, but MPPTs may allow more in some circumstances. But I'm sure an expert will correct that if necessary.

Of course you're right, that's quite wrong. [smilebigeye]

Basically, a PWM regulator is a fast electronic switch between the solar panel and the battery. If the battery charge level is low enough, the regulator stays on 100% of the time and allows the battery to be essentially direct connected to the panel. The panel output voltage is dragged down to just above the battery voltage, reducing its power output. Once the regulator sees the battery voltage reach it's set limit it switches off the panel for a percentage of each pulse that the regulator lets through, keeping the voltage to that level. This is what Pulse Width Modulation means, the length of each short pulse's on time can be expressed as a percentage value. This is far better than a simple analogue controller, which would get quite hot dissipating the extra power.

Now a MPPT controller does even better, it allows the panel voltage to be much higher than battery voltage, keeping the solar output near the most efficient output level. Then the magic beans inside the regulator turn the DC output into high frequency AC and transform it to battery charging voltage with a small transformer. Then it is rectified again to DC to charge the battery. This "switch mode" operation is similar to that used by modern power supplies and is quite efficient. Of course as the battery gets fuller the efficiency is irrelevant as you need to reduce the current to prevent over voltage. It is therefore only more effective at charging a battery that is not too full to accept the maximum current the regulator can provide.

As a simple example, a 120W panel will produce say 6 amps at 20 volts under ideal conditions. Connect that to a discharged battery with your PWM regulator and you'll likely get only 6.5 amps at 13 volts, or about 84W of power. Use a MPPT regulator on the other hand and you'll have 120W less say 10% efficiency loss equals 110W. Divide 110W by 13V and you get around 8.5A available for charging. That's where your extra 30% output current comes from, reading the output power of the panel and converting it with smart electronics instead of dumb ones.

Hope that's clear. [bigrolf]

[DiscoMick]

Excellent explanation - thanks. I knew someone would say it better than I could.

[Rick1970]

Have a cheap 100w panel on the disco with a cheap pair controller, 100ah battery. Keeps up with Engel ok, but I do 100km most days too. Usually drops to 12.6ish over nite. In the habit of keeping frozen 2L coke bottles in fridge if there is not much in there as well. Seems to help

[101RRS]

Hope that's clear. [bigrolf]

Well thats the theory at least - like all things real life experience may be different.

[slug_burner]

From my experience it comes down to how cold you set the fridge temperature. Obviously the environment that the fridge is in will also make a big difference. When I set my fridge to freeze it chews through the power. On the same trip a friend sets their fridge to 4C and he manages without draining his battery.

As for controllers, I have both and do get more juice from the MPPT than the PWM. However the efficiency improvement can be overcome by using a bigger solar panel usually at a lower cost than paying for a reputable MPPT charger. Size of panel just comes down to space available.

I think panels can also be overrated just as PWM controllers are passed off as MPPT. I have 400W of flexible panels yet the most I have seen coming out of them was 14 Amp which no matter what state of voltage the battery is at means that you are pushing only approx 50% of the rated panel power into the battery.

If I was starting from scratch on a system design I would spend a bit of time on getting the insulation on the fridge right. Nearly all car fridges use an insulating cover/bag, that helps a fair bit. A good chunky walled fridge with good insulation value will overcome many of the other areas of the system that could be improved.

[trout1105]

The 160w flexible solar panel on my boat has carked it, Its only putting out 1.5a even on a nice sunny day.
This is the second panel to die, The first one was a $700 fold up 120w Primus panel that only lasted 3 months because it couldn't handle getting wet and all the wiring connections in the panel corroded and failed unfortunately.
The 160w panel doesn't appear to have any corrosion or damage that is visible But it still only puts out 1.5a Max, When new the panel was putting out 4a-5a.
I have ordered a 250w flexible panel ( 12.60a rated output) to replace the dead 160w unit and I am hoping that this one will last more than the 6 months the old one lasted.
I only paid $79 for the no name 160w panel So I probably got what I paid for, The new 250w panel cost me just under $200 and it appears to be a better quality unit it is also IP65 rated.
I do have a new 125w Companion folding solar blanket that puts out about 6a on the boat (Just in Case) But I cant fit that permanently because the corrosion from salt water spray will kill it like the last one.
The fixed ridged panels I have fitted onto the 79 series, Navara and the caravan haven't missed a beat and are still working perfectly and I am wondering if the flexible panels are an inferior design to the ridged ones.

[weeds]

I’ve also have issue with cheap semi flexible panels.

The new $400 panel puts out more than to two same size cheapies

[DiscoMick]

The 160w flexible solar panel on my boat has carked it, Its only putting out 1.5a even on a nice sunny day.
This is the second panel to die, The first one was a $700 fold up 120w Primus panel that only lasted 3 months because it couldn't handle getting wet and all the wiring connections in the panel corroded and failed unfortunately.
The 160w panel doesn't appear to have any corrosion or damage that is visible But it still only puts out 1.5a Max, When new the panel was putting out 4a-5a.
I have ordered a 250w flexible panel ( 12.60a rated output) to replace the dead 160w unit and I am hoping that this one will last more than the 6 months the old one lasted.
I only paid $79 for the no name 160w panel So I probably got what I paid for, The new 250w panel cost me just under $200 and it appears to be a better quality unit it is also IP65 rated.
I do have a new 125w Companion folding solar blanket that puts out about 6a on the boat (Just in Case) But I cant fit that permanently because the corrosion from salt water spray will kill it like the last one.
The fixed ridged panels I have fitted onto the 79 series, Navara and the caravan haven't missed a beat and are still working perfectly and I am wondering if the flexible panels are an inferior design to the ridged ones.Is there a way to seal the connections, maybe using grease, plastic pipe or tape?

[trout1105]

Is there a way to seal the connections, maybe using grease, plastic pipe or tape?
I have used MC4 connectors so waterproofing isn't the issue with the 160w panel, It's simply a crap panel and at $79 I got what I paid for.

[DiscoMick]

Yes, I have a MC 4 connector and it's fine, although I did seal it with duct tape.
Certainly seems to be a big quality difference with solar panels.

[trout1105]

Yes, I have a MC 4 connector and it's fine, although I did seal it with duct tape.
Certainly seems to be a big quality difference with solar panels.

I am not a fan of tape on electrical connections especially when moisture is concerned as I find that the tape tends to hold the moisture in.
If I need a watertight connection I usually use silicon and heatshrink.
I had problems in the past with joins that get wet shorting and corroding so I experimented with putting a smear of silastic over the join and an inch either side of it and then covering it in heatshrink before the silicon set completely.
This is especially effective on joins like bilge pumps, boat lights etc.[thumbsupbig]
You can get commercial waterproof joining kits But they are bloody expensive, Heatshrink and silicon are cheap as chips and readily available[biggrin]

[trout1105]

I fitted the 250w pannel to the boat today, WOOHOO it's pushing 11a+ in full sun and 3.5a in overcast conditions[thumbsupbig]