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ecuadoramalavida

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Posts: 4
Reply with quote  #1 
Hi,

I own a small camper van and do a fair bit of off-grid camping. I don't need much electricity and am on a small budget. Also, the system should be as light as possible as I can't add much weight to the camper.

I want to power the following devices:
- 35W fridge 12h/day
- some lights 30-70W 1-2h/day
- charge 2-3 phones every day suppose 20-30W 1-2h/day

I'm traveling close to the Equator line, so I can expect some good 8-10 hours of sun light all year round. Perhaps half year its cloudy and rainy but stil quite bright and sunlight coming through now and then. I'm looking at panels of 80 to 150W.

I don't have an additional house battery. All appliance are run off the starter battery. I just bought a new battery, a 100AH Bosch S3. I would want to avoid adding another battery due to the weight of car batteries and prices of gel batteries. 

I want to connect the solar panel to my starter battery, in a way that its disconnected while the engine is running.

Panels:
Since I am in Quito, Ecuador, solar panel options are extremely limited. I could source the following (all from China):
Monocrystalline:
EGE Eco-Energy EGE-150M-36 (Datasheet) ($168)

Policrystalline:
Guangdong Prostar 80 Watts 12v 4,44a (some info here) ($70) 
Gi-Power GP-150P-36, 12V (Datasheet) (waiting for quote)

According to the datasheets, the Gi-Power has the highest panel and cell conversion efficiency while the internet tells me mono panels are better...

Charge controller:
I can buy below charge controller. 10A and 20A are available from Guangdong Prostar. I found a ton of alike looking ones on Amazon from different Chinese manufacturers... I like it due to the LED and information it can display.
[controlador-carga-panel-solar-12v24v-20-amp-prostar-D_NQ_NP_818211-MEC27079938120_032018-O] 
There are two alternatives which both only support 10A:
[controlador-de-carga-panel-solar-1224v-10a-controlador-D_NQ_NP_652168-MEC25583403534_052017-F]  [controlador-de-carga-solar-10-amperes-1224-volts-tec-pwm-D_NQ_NP_15661-MEC20106796179_062014-F] 
Prices are the same, but I don't have more info, only the pictures.

So here are my questions:
Panels & charge controller
1. Would the 80W panel be enough or should I rather go for one of the 150W panels?

2. Is a 10A controller enough for the 150W panels? According to the seller and the panel current rating yes. But the label on the controller states that it supports max 120W[confused]

Installation:
3. If I go with the 80W and would add another panel in the future, would it be as easy as wire them up in parallel?
4. What gauge of wire should I use to wire the panels to the controller and to the battery?
5. I believe charge controllers to run off the connected battery and they don't have on/off switches. So would it be enough to add a switch between charge controller and battery to shut if off while driving? Or would I need to add a switch between panel and controller?

Thanks for any help!

stmbtwle

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Posts: 2,800
Reply with quote  #2 
Hi Welcome to the forum!

1. As you are looking at a camper, I'd go with the 80 watt with the option of a second one if needed. A 150w panel is big and awkward to move around. 

2. I'd go with the 20 amp, there's not that much difference in price and you can add more panels.

3. Connecting 2 x 80w in parallel is easy as long as the charge controller can handle both of them.  

4. For a short distance (10 ft), 14 ga (US measurement) wire size should be fine. If you are going to use a long wire (50-100') 12 ga wire would be better. Don't know what those would be in metric sizes. The longer the wire the bigger it needs to be, if in doubt go the larger size for less resistance.  You can download "ampacity tables" to help you choose. 

5. You don't need a switch in either place.  The charge controller and the alternator each have their own diodes.  If the battery is low they will work together, as it reaches charge one or the other will shut off first.  I've done this for years on my boat with no problems.  Everything is automatic.

6. I would consider making the panels portable with a disconnect plug and a long wire.  This way you can park in the shade and put the panels in the sun, oriented toward the sun. Works for me.

7. I would really, really recommend a second battery, and keep them separated.  Running your accessories off the starting battery could leave you stranded.  You can connect them with a jumper cable for charging if desired.  There are also "battery combiners" which will do it automatically but they're not cheap.



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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
ecuadoramalavida

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Posts: 4
Reply with quote  #3 
Quote:
Originally Posted by stmbtwle
Hi Welcome to the forum!


Thanks a lot for all the great info and kind welcome!

1. Have you heard about Guangdong Prostar before? Usually panels cost 1USD/watt or more, but this one is cheaper so I'm a bit worried about the quality.

1. 5. I will definitely have to mount the panel onto my roof because otherwise I can only use it when around the van. I'm traveling in South America and even though its pretty safe better not leave any valuables unattended in the open. Perhaps should I get a second one in the future I will make it portable.

4. 10ft good enough. I can place the charger quite close to the panel, some 2ft distance. Haven't quite figured out the route to the battery yet, but should not be more than 10ft. 

5. I do trust my alternator, but I wasn't sure about these cheapo Chinese controllers. My main concern is that it may get damaged when starting the engine as current spikes.

7. I will add a house battery later, at the moment I don't have the space. If I get stranded I will need to wait for the sun to recharge. My bigger fear is to deep discharge the battery and damage it...

On the last point, is there some battery protection that would shut off all appliances (all wires join at a central point and then connect to the battery) when the battery gets 50% discharged?

After reading more and more, I got some more questions:

Ground:
8. My chassis is grounded. So is it safe to directly connect the panel ground wire to the chassis? Same question for charger controller ground wire to battery (-).
Fuses:
9: Will I need to add any fuses?
stmbtwle

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Posts: 2,800
Reply with quote  #4 
All the controllers you pictured have 6 terminals. Generally, if you connect the loads to the load terminals you are current-limited and the controller will shut them off if voltage gets below a certain setting. On some you can also set a timer. If you connect them to the battery (such as the starter), these features are bypassed.

Not familiar with the panel you mention, but nearly all rigid panels are good for 20 years or more. Flexible ones about 10. Flexible are MUCH lighter, and may be more suitable for your application if you can get them.

8. Yes

9. Fuses won't hurt. Follow directions.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
ecuadoramalavida

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Posts: 4
Reply with quote  #5 
Quote:
Originally Posted by stmbtwle
All the controllers you pictured have 6 terminals. Generally, if you connect the loads to the load terminals you are current-limited and the controller will shut them off if voltage gets below a certain setting. On some you can also set a timer. If you connect them to the battery (such as the starter), these features are bypassed.


That's perfect. Means I need to factor in a bit more wiring I would have otherwise not accounted for!

Haven't come across a flexible panel here unfortunately. But the 80w panel really is not too heavy.

I'll buy the stuff tomorrow and see how it comes along.

Thanks a lot!
stmbtwle

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Reply with quote  #6 
You don't have to run your load wires all the way to the battery unless they are heavy loads. Simply connect to the "bat" terminals of the controller. If you want them to be regulated, connect to the "load" terminals per directions.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
marsbrook

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Posts: 4
Reply with quote  #7 
sometimes the battery capacity determines the solar panel powers.  80W is enough for the DC applications you mentioned.
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ecuadoramalavida

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Posts: 4
Reply with quote  #8 
Thought I’d post a few thoughts after having used the system for a while now.

Panel: I think the panel works surprisingly well, even in low light settings. Has been cloudy most of the time but so far always had enough electricity for my needs. Anyhow, next time I would opt for a bigger panel, just to be on the safe side (but I think that’s a usual solar user phenomenon, always longing for more power).

Controller: Its as cheap as it gets. Really low build quality, but gets the job done. Mine is mounted above the dinner table which makes the two USB ports a nice feature for charging a phone. For others may be a completely useless addition. The information it can display turned out to be not as useful as I thought. It basically got a voltmeter and that’s it (whish it could display charge current). You can use between 3 battery types (wet, AGM, gel). It let’s you set the float charge voltage, load disconnect and reconnect voltages as well as load on 24h or only on during sun hours.
You can connect max 20A of load. So if you need to draw more current you can’t use the battery protection features (not sure if all controllers are generally designed that way but I feel its a bit odd that charge current and discharge current are equal).
Finally, I did buy a 100A house battery and I’m glad I did it! I ran a cable from starter battery to controller so that I can switch the load over when the engine is running.

Thanks a lot for the help so far!

I’m just wondering what would be needed if I wanted to charge the house battery off the alternator? The cable is 10AWG and 5m long. I would need a bigger cable wouldn’t I?



stmbtwle

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Reply with quote  #9 
10awg should do the job. Larger would be better but I'm not sure it's worth the expense.

A simple parallel switch between the batteries will work, BUT you have to remember to turn it off when you stop.

Another option would be a continuous duty solenoid, actuated by your ignition switch.

Or you could use a "battery isolator" which is a couple big diodes. It has a small voltage drop though.

Probably best would be a voltage sensitive relay or "battery combiner", but they're not cheap.

https://www.bluesea.com/articles/58

None of them are hard to hook up.

On ebay you can get digital combination volt-amp meters for a few dollars.

https://www.ebay.com/itm/US-DC-100V-10-50-100A-Voltmeter-Ammeter-LED-Dual-Digital-Volt-Amp-Meter-Gauge/253530841811?hash=item3b079da2d3:m:m61j9Y0RijZnCHFx2VbfCxw

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #10 
I don't have an additional house battery. All appliance are run off the starter battery. I just bought a new battery, a 100AH Bosch S3. I would want to avoid adding another battery due to the weight of car batteries and prices of gel batteries.

If you do it this way you will be paying more for starter batteries. Starter batteries are engineered to start the vehicle and stay topped off, they do not respond well to repetitive discharging. Doing so will shorten a starter batteries lifespan considerably. If you make use of a deep cycle house battery, it will be easier on your bank account in the long run.


On the last point, is there some battery protection that would shut off all appliances (all wires join at a central point and then connect to the battery) when the battery gets 50% discharged?

The term is "Low voltage disconnect" you can buy low voltage disconnects as a separate unit. Some inverters have a programmable low voltage disconnect. Most inverters have a low voltage disconnect but it is set to low to protect the battery, it there to protect the inverter. 

I’m just wondering what would be needed if I wanted to charge the house battery off the alternator? The cable is 10AWG and 5m long. I would need a bigger cable wouldn’t I?

A Battery isolator will connect the house batteries to the alternator when the alternator is running and isolate the house batteries from the starter battery when the alternator is shut down, preventing the aux loads from drawing power from the starter battery.

You can get combined Battery isolator / Low Voltage disconnect.





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Rick H Parker
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