2 -(6v) batteries vs 2 (12v) batteries

[DavidM]

That 100' roll of 10 gauge cable looks perfect for hooking up your panels.

I am not a fan of cheap Chinese made solar controllers like the one you referenced. A good MPPT controller is expensive, but you would only lose maybe 15-20% if you used a PWM controller.

Morningstar makes good PWM controllers. You will need at least a 10A one like this one for $51.00:

https://www.amazon.com/SunSaver-Charge-Controller-12V-10A/dp/B002MQW3H8/ref=sr_1_4?ie=UTF8&qid=1497969010&sr=8-4&keywords=morningstar+pwm+charge+controller

Or this one if you want to mount it outside as it is waterproof:

https://www.amazon.com/Morningstar-SK-12-SunKeeper-Charge-Controller/dp/B007NYZ5VU/ref=sr_1_12?ie=UTF8&qid=1497969010&sr=8-12&keywords=morningstar+pwm+charge+controller

David

[Merlin]

Davidm is right on about charge controllers. The Morningstar PWM controllers he referenced are excellent; I've use one of those for years. I've also used this one (and MPPT controller) for years and have had excellent performance:

https://www.solar-electric.com/mosumpsochco.html

For even more money, you can buy a meter for that charge controller to have fun seeing what's going on:

https://www.solar-electric.com/mormredime.html

[thedusty]

That 100' roll of 10 gauge cable looks perfect for hooking up your panels.

I am not a fan of cheap Chinese made solar controllers like the one you referenced. A good MPPT controller is expensive, but you would only lose maybe 15-20% if you used a PWM controller.

Morningstar makes good PWM controllers. You will need at least a 10A one like this one for $51.00:

https://www.amazon.com/SunSaver-Charge-Controller-12V-10A/dp/B002MQW3H8/ref=sr_1_4?ie=UTF8&qid=1497969010&sr=8-4&keywords=morningstar+pwm+charge+controller

Or this one if you want to mount it outside as it is waterproof:

https://www.amazon.com/Morningstar-SK-12-SunKeeper-Charge-Controller/dp/B007NYZ5VU/ref=sr_1_12?ie=UTF8&qid=1497969010&sr=8-12&keywords=morningstar+pwm+charge+controller

David

Thank you.

I'm still learning about panels...would these handle a second 100w panel if I added one?  Which is the best way to determine this when looking at a charge controller...its amp rating?

[Pinstriper]

My head spins whenever I look at this stuff.

Is there a single converter/charge controller that would replace what we currently have, taking AC, DC from the TV, and solar, all driving to a battery bank, and also if connected to shore power drive the AC circuits ?

Or do you have a separate solar controller hooked up directly to the batteries, side by side with the main converter/charger unit we already have ?


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[DavidM]

thedusty:

You can get close enough to the amperage rating you need for your solar controller if you take wattage and divide it by 12. So for a pair of 100 watt panels, you need a controller with at least an amperage rating of 200/12 = 17 or practically at least 20 amps.

At 200 watts you are at the point where a MPPT controller might make sense. Go to wholesalesolar.com and click on their charge controllers. These like Bluesky, Morningstar, etc are all American designed, Chinese made like most things, but American quality management.

So looking at that site you can find a Midnight Solar PWM controller for $89 or a Blue Sky MPPT controller for $200, both rated for 20A. The extra $111 produces about 30-40 watts more usable power. But if you really only need 160 watts usable, the PWM controller is much cheaper.

David

[DavidM]

Pinstriper:

What you describe is fairly routine for boats and some more expensive RVs. This is what it takes:

You need a fairly robust battery bank, at least a pair of golf cart batteries and preferably two pairs if you are going to draw much AC from the system.

That "house bank" as it is called in the boating world, is connected to an inverter/charger, preferably one with a built in transfer switch. Your 120V shorepower is connected to the AC in side of the inverter/charger and the AC out side is connected to your house AC main panel so it can power all of the RVs AC loads.

Then when you are hooked up to the campground's shore power, the transfer switch passes the power through to power the AC loads in your RV. It also powers the charger (just like a converter which you won't need with this system) which charges the batteries.

When you are not hooked up to shore power, the transfer switch automatically switches to inverter generated AC power which then supplies all of the RVs AC loads. You can power a microwave (for 5-10 minutes to warm something up), the TV and have AC at the outlets to plug in a hair dryer (but again not for long), etc. But don't try powering the air conditioner with the inverter. A 12,000 btu A/C requires about 15 amps at 120V which takes 175 amps DC. That will run your two pairs of GC batteries down below 50% in an hour.

To replace all of those amps that the inverter uses you need solar panels and a controller hooked up to the house battery bank. As described in the previous post, you can put a twin 100 watt panel system together for about $400 for panels, controller and wiring.

As far as I know there is not a single package solar controller, inverter and charger. It takes at least two components to do what you want.

That kind of system won't be cheap. $400 for four GC batteries and $400 for a 1,000 watt modified sine wave inverter/charger or $1,000 for a pure sine wave 2,000 watt unit. Plus some heavy wiring.

So most of us just use cigarette lighter plug in inverters that are good for 150 watts AC, or a bit more than an amp at 120V. Good for powering a TV or laptop, but not much else.

David

[Merlin]

There are companies that pre-assemble everything needed for you with the charge controller, inverter, charger (converter), switches and generator or shore power input all in one unit. They are, however, very spendy, very large, and very heavy to provide the capacity needed. All these need is to attach the solar panel wires, the battery wires, the shorepower wires, and the house (camper/boat) fuse/breaker panel wires. They handle all the electron traffic. The one below is for a 24 volt battery bank, but can be configured 12 or 48 volt too. And, as noted above, not enough output or storage for air conditioning (don't even think about it).

https://www.solar-electric.com/midnite-mnsw2524-kid-b-schneider-electric-system.html

[Pinstriper]

Actually I don't care about the inverter, I have no intention running AC off the batteries - those circuits would only be lit when on shore power.

I just want a single unit that can take input from AC shore power, DC from solar and TV, and both charge batteries and drive DC circuits, plus drive AC circuits while on shore power.


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[thedusty]

thedusty:

You can get close enough to the amperage rating you need for your solar controller if you take wattage and divide it by 12. So for a pair of 100 watt panels, you need a controller with at least an amperage rating of 200/12 = 17 or practically at least 20 amps.

At 200 watts you are at the point where a MPPT controller might make sense. Go to wholesalesolar.com and click on their charge controllers. These like Bluesky, Morningstar, etc are all American designed, Chinese made like most things, but American quality management.

So looking at that site you can find a Midnight Solar PWM controller for $89 or a Blue Sky MPPT controller for $200, both rated for 20A. The extra $111 produces about 30-40 watts more usable power. But if you really only need 160 watts usable, the PWM controller is much cheaper.

David

Thank you to everyone for all the help.  I've been tied up so I need to sift through it better and read more. 

I'm leaning towards buying the "good" MPPT models mentioned with at least 20A ability with the idea of...buy one, cry once.  I'm leaning towards the MPPT model b/c for whatever reason the idea of losing 20% efficiency angry...though it's not rational...  But neither was spending gobs of money on an all-aluminum travel trailer...  ;-)

I need to look closer and see if any of these MPPT models are waterproof too and could be mounted outside if needed.

[thedusty]

thedusty:

You can get close enough to the amperage rating you need for your solar controller if you take wattage and divide it by 12. So for a pair of 100 watt panels, you need a controller with at least an amperage rating of 200/12 = 17 or practically at least 20 amps.

At 200 watts you are at the point where a MPPT controller might make sense. Go to wholesalesolar.com and click on their charge controllers. These like Bluesky, Morningstar, etc are all American designed, Chinese made like most things, but American quality management.

So looking at that site you can find a Midnight Solar PWM controller for $89 or a Blue Sky MPPT controller for $200, both rated for 20A. The extra $111 produces about 30-40 watts more usable power. But if you really only need 160 watts usable, the PWM controller is much cheaper.

David

I just ordered the Blue Sky model.

https://www.amazon.com/gp/product/B007S1HA2K/ref=ox_sc_act_title_1?smid=A31H76PZNDKUUJ&psc=1

My wife is an exec at Amazon...so I get an earful if I don't order through them.  Ha.

Anywho, do I need an LCD monitor to go with it?  If so, is there a "cheap" version that will do the trick?

[DavidM]

That Blue Sky controller should work great. You could even parallel three 100 watt panels and use it with them given the 25A spec.

I wouldn't buy Blue Sky's monitor. Others have installed the Drok battery monitor that Amazon sells for about $30. it gives instantaneous voltage and amperage and cumulative watt hours consumed or added. I am going to install one the next time we go camping and will provide feedback.

David

[Merlin]

You don't need a monitor for the controller to work fine, but they are fun. If you want a Blue Sky monitor, you can get a less expensive version than the "Pro". Here's one for $80.

https://www.solar-electric.com/iprediforimo.html

I don't want to rain on Davidm's parade and I've never used a Drok monitor and they may be absolutely fine, but all three things I have purchased under the Drok name either came defective out of the box or failed soon after installation.

[DavidM]

Merln:

It's ok as it is not really my parade. Tinkeringtechie, who now posts on the other LL forum, introduced me to it. Yes, it is Chinese and most Chinese stuff is a POS- see my comments above on Chinese solar controllers. But for $30 I decided to roll the dice. It goes beyond the Blue Sky monitor as it shows cumulative watt hour use/charging input.

David

[thedusty]

That Blue Sky controller should work great. You could even parallel three 100 watt panels and use it with them given the 25A spec.

I wouldn't buy Blue Sky's monitor. Others have installed the Drok battery monitor that Amazon sells for about $30. it gives instantaneous voltage and amperage and cumulative watt hours consumed or added. I am going to install one the next time we go camping and will provide feedback.

David

Is this the one you're referring to?  I'll give this a shot and if it breaks I'll have Amazon replace it.


DROK DC 0-120V 0-100A Digital Multimeter Charge-Discharge Battery Tester, Volt Meter/Ammeter/Watt Meter/Time/Capacity/Electricity Usage Monitor, LCD Color Screen with Overvoltage Protection https://www.amazon.com/dp/B01M5CWR2P/ref=cm_sw_r_cp_api_dQUszbR6F8Q8J

[DavidM]

That is the one. I bought mine from Amazon as well and I suppose if it doesn't work I can return it. But the aggravation is more significant than the $30 ;-).

David