installing solar power in a westy

[MattBW]

My 80w panel kicks out upto (E D I T: corrected numbers) 4.45a .

I do want to get a compressor fridge in at some point so will look forward to trying it out. A review I read said they ran a compressor fridge for a month on a 60w panel and battery. However they didn't run anything else with that and it was probably ran in summer.

My battery is permanently full with just using lighting, tv use and charging iphones, iPads and gopros. Admit much of that charging was in the day, tv in the dark. However that was mid September and not February. Imagine in autumn winter a charger may be required.

If anyone wants to loan me a compressor fridge I'm happy to test it lol :p

[ninja.turtle007]

I think I'm being realistic in hoping that on long sunny days my 100w panel will be able to keep up with the compressor fridge over a 24 hour period. On cloudy days I may as we'll not have a solar panel.

I have solar panels from an old van I had that are sat on my garage roof. Although they are 25 years old in direct sunlight they still put out just over 2 amps whilst laid flat in winter sunshine.

I will have my panel fitted over the next couple of days so we'll see what it can do.

[ninja.turtle007]

My 80w panel kicks out upto 8.5 - 9a if I remember right.

I really don't know very much about all of this but my understanding is that a 100w panel in optimum conditions will not put out more than 6A.

[MattBW]

My 80w panel kicks out upto 8.5 - 9a if I remember right.

I really don't know very much about all of this but my understanding is that a 100w panel in optimum conditions will not put out more than 6A.

Apologies you are right, i was recalling a number from the regulators manual haha. I just dug the paperwork out, my 80w semi flex panel has max output of 4.45a per hour, 100w would be 5.56a.

[ScienceBoy]

Sweet

[printmonkey]

My 80w panel has been giving 1.1a in the last few days in pretty poor winter sunshine. Probably not enough for a fridge, but both batteries are being charged. I'm keen to see what happens with your cr50 fridge over the summer Tom as I would like to buy a portable waeco fridge next year.

[Timwhy]

I think everyone needs to put their wants and desires in perspective. If you want to run a compressor fridge and anything else you'll need a large enough battery bank(capacity) and a large solar panel or panels to quickly charge that battery bank. I have a compressor fridge and they do eat batteries, if this is all that I run then I should not have any issue with 134 amp hour capacity with a 135 watts panel. In the real world that's not the case, I want to run my radio and lights, sink pump, shower pump, coffee grinder, tv etc..... You get the picture. The more you use the bigger and quicker you need to get! Figure out your needs and this will tell you what you need in equipment, then add half again as much and you should be good to go. But the final thing is you will be at the Mercy of the Sun, hope you have plenty of it!

[CJH]

Apologies you are right, i was recalling a number from the regulators manual haha. I just dug the paperwork out, my 80w semi flex panel has max output of 4.45a per hour, 100w would be 5.56a.

I just read about MPPT controllers here.

5.56A at a bulk charging voltage of 14.4V = 80W. This is the problem with solar panels, whose output voltage depends on light level and temperature, and are therefore set to output 18-19V in ideal conditions. If they produced a lower voltage in ideal conditions, then under less than ideal conditions they may not produce anything useful for a 12V setup. That quoted 5.56A is for 18V.

If a simple controller reduces the panel's output voltage (via a resistor I guess) at constant current, then that 5.56A stays constant and the voltage is adjusted to suit the battery requirements. If the battery needs 14.4V, then it'll give 5.56A x 14.4V = 80W. If the battery is depleted and needs 12.5V to charge, then 5.56A x 12.5V = 70W. It's ironic that this type of controller wastes most energy when the battery needs it most.

An MPPT controller finds the voltage at which the product of voltage x current (i.e. power) is a maximum, and then uses a transformer, via a high frequency AC conversion, to convert that voltage to the required voltage with, apparently, 93%-97% efficiency. So that 5.56A at 18V would become 6.45A at 14.4V (at 93% efficiency), or 7.44A at 12.5V. So it gives most current when your battery needs it most.

6.45A instead of 5.56A isn't much of a gain I guess (16%). 7.44A instead of 5.56A is better - 34% gain. Every little helps.

[jed the spread]

I think everyone needs to put their wants and desires in perspective. If you want to run a compressor fridge and anything else you'll need a large enough battery bank(capacity) and a large solar panel or panels to quickly charge that battery bank. I have a compressor fridge and they do eat batteries, if this is all that I run then I should not have any issue with 134 amp hour capacity with a 135 watts panel. In the real world that's not the case, I want to run my radio and lights, sink pump, shower pump, coffee grinder, tv etc..... You get the picture. The more you use the bigger and quicker you need to get! Figure out your needs and this will tell you what you need in equipment, then add half again as much and you should be good to go. But the final thing is you will be at the Mercy of the Sun, hope you have plenty of it!

I think this is the key point, there is loads of info on the net with figures and quotes etc but the bottom line is do they work and if so how well with how you use them. Compressor fridges are amazing and work no matter how hot it gets in the sun and the hotter inside the vehicle gets the harder they work and more power they use. While quoting figures of power inputs/outputs it might pay to take into consideration the maximum ambient temperature in the manual that your fridge is designed to work at and you might find that the fridge is being used above the manufacturers guide lines. The fridges still work fine but when its 50*C inside the van manufacturers guide lines go out of the window. If you want to save power then I would personally keep the van as cool as posable and park the van in the shade, not much good with solar panels on the roof. It would be better to have one of those roll out panels like lots of overlanders use so you can park your vehicle in the shade and have the panel out in the sun and when its not megga hot and there is no shade just throw it on top of your side awning out of the way. Also in the winter think about snow on your roof and I know this wont apply to everyone but dust needed to be cleaned off mine on our very recent trip to the Sahara, look at the state of the windows to get the idea.





Thats why in my personal experience you would have to go a long way to beat a Sterling Charger if you want to be self surfactant.

Jed

[ninja.turtle007]

Thats why in my personal experience you would have to go a long way to beat a Sterling Charger if you want to be self surfactant.

Jed

I agree, it would take a huge array of panels to put out 50A when the batteries are really flat like the Sterling does.

I did loads of calculations for different scenarios when I bought my compressor fridge. In the real world they don't work out, the batteries do not cover my power requirements as I expected. At the time you told me so!

The reason I'm fitting a panel is to hopefully increase the time the batteries will last before needing to start the engine. I don't expect it to keep be able to keep up withe the power demands. Also to keep the batteries fully charged whilst the van is not in use.

[ScienceBoy]

All the end of the day it can only help, and once it's in there's no ongoing costs.

[keith]

Ive just measured mine....max i could get was 3.9 amps.

That was by waving it around to get the perfect angle to the sun.

Lying down it dropped to 2.3 which is ....interesting.

Ps.panel is not fitted yet...straight out of the box

[ninja.turtle007]

Ive just measured mine....max i could get was 3.9 amps.

That was by waving it around to get the perfect angle to the sun.

Lying down it dropped to 2.3 which is ....interesting.

Ps.panel is not fitted yet...straight out of the box

Did your controller arrive Keith? I bought one from you link and I received an email about waiting for stock.

How are you measuring the current? As the current will vary depending in the charge state of the battery.

[keith]

Ive just measured mine....max i could get was 3.9 amps.

That was by waving it around to get the perfect angle to the sun.

Lying down it dropped to 2.3 which is ....interesting.

Ps.panel is not fitted yet...straight out of the box

Did your controller arrive Keith? I bought one from you link and I received an email about waiting for stock.

How are you measuring the current? As the current will vary depending in the charge state of the battery.

No email....no controller yet tom.

I measured it by connecting a multimeter to the mc4 connectors ....just on the drive.

[keith]

Ive just measured mine....max i could get was 3.9 amps.

That was by waving it around to get the perfect angle to the sun.

Lying down it dropped to 2.3 which is ....interesting.

Ps.panel is not fitted yet...straight out of the box

Did your controller arrive Keith? I bought one from you link and I received an email about waiting for stock.

How are you measuring the current? As the current will vary depending in the charge state of the battery.

No email....no controller yet tom.

I measured it by connecting a multimeter to the mc4 connectors ....just on the drive.