Powering a fishing cabin with solar, How to charge batteries with the panels.

[SpaceOddacy]

Ok, so I made a thread on camping last week and learned quite a bit. I'm back and wondering how do you charge a battery bank with the solar panels? I have read on the forum that you could hook a solar panel directly to a battery and internal resistance would keep the battery from charging over 100%. Is this correct or was that person insane?

In any case I figure (from what you guys have taught me so far) that you get almost 10% less than what the panel is rated for.

My cabin is used only for small hunting parties with friends and fishing trips on the weekends. (as stated in previous thread I love the out doors so this place is my proverbial man cave)

Tons of power isn't needed, lighting at the moment as well as all power is supplied by a honda generator that I picked up on the cheap at a yard sale.


I could easily rewire the cabin and use LEDS for lighting at night, I have a 12volt water pump that draws around 7amps. 12 volt 6.8amp pump

its rated at 6.8 amps but it will draw more under load I'm sure so figure at 7.5 amps. 7.5amps x 12v = 90watts.

**Note this pump would only be running when using the sink. Luckily the cabin is about 20feet from a stream, the sink I never removed in case I somehow got a permanent power supply out there.

So I figured 2\3 deep cycle batteries in parallel would be sufficient for occasionally running the pump 'maybe once a day for a few minutes to clean fish or wash meat'. This system would also be required to run a 12volt cooler that I referenced in my other thread.

I was thinking that 4 100watt panels as the only thing drawing on the system would be the cooler,LEDS at night and the occasional water pump after I caught or shot something and the LEDS at night.

400watt panels less the 10% loss in efficiency I assume it would be about 350 watts.
I have a distribution block and wiring, a few friends and a case of beer to help with the wiring and building of the cage for the panels.

Q. do you think 350 +\- watts would be enough for my requirements to charge the batteries and such.

Q. what I heard about charging the batteries with solar panels and not needing a trickle charge system is that true or is there something I should buy that would turn itself off like a trickle charge system?

[Sunking]

Ok, so I made a thread on camping last week and learned quite a bit. I'm back and wondering how do you charge a battery bank with the solar panels? I have read on the forum that you could hook a solar panel directly to a battery and internal resistance would keep the battery from charging over 100%. Is this correct or was that person insane?

Insane.

In any case I figure (from what you guys have taught me so far) that you get almost 10% less than what the panel is rated for

Correct but I doubt in the context you are thinking of. Calculations are based on solar sun hours and lab STC ratings. Just because yu have a 100 watt panel and the sun shines in your area 12 hours per day means you can harvest 100 watts x 12 hours x .9 = 1080 watt hours. Far from it. More like 300 to 500 depending on location and time of year.

My cabin is used only for small hunting parties with friends and fishing trips on the weekends. (as stated in previous thread I love the out doors so this place is my proverbial man cave)

OK that is a start as it means you do not need a full blown 24 x 365 day year system. However a lot of information is needed.

• What time of year
• Location
• How many watt hours each day you are there.

I could easily rewire the cabin and use LEDS for lighting at night

Well right idea but maybe the wrong technology LED's are not what they are cracked up to be as hyped. They are no better than CFL's and much more expensive. T5 tubes are the most efficient for interior lighting, but in you rcase may not need high quality CRI lighting. 12 volt CFL sound to me to be the better choice at this moment.

I have a 12volt water pump that draws around 7amps. 12 volt 6.8amp pump

its rated at 6.8 amps but it will draw more under load I'm sure so figure at 7.5 amps. 7.5amps x 12v = 90watts.

**Note this pump would only be running when using the sink. Luckily the cabin is about 20feet from a stream, the sink I never removed in case I somehow got power out there.

From what you described the power requirements can be ignored at this point as they are insignificant.

So I figured 2\3 deep cycle batteries in parallel would be sufficient for occasionally running the pump 'maybe once a day for a few minutes to clean fish or wash meat'. This system would also be required to run a 12volt cooler that I referenced in my other thread.

There is no reason to use any parallel battery configuration in this application. It will only add cost, complexity, and maintenance. A single battery string of the appropriate AH capacity is called for.

I was thinking that 4 100watt panels as the only thing drawing on the system would be the cooler,LEDS at night and the occasional water pump after I caught or shot something and the LEDS at night.

400watt panels less the 10% loss in efficiency I assume it would be about 350 watts.
I have a distribution block and wiring, a few friends and a case of beer to help with the wiring and building of the cage for the panels.

Highly unlikely you need this much for a few lights and a water pump for weekend use.

Q. do you think 350 +\- watts would be enough for my requirements to charge the batteries and such.

I think it is overkill but would work.

Q. what I heard about charging the batteries with solar panels and not needing a trickle charge system is that true or is there something I should buy that would turn itself off like a trickle charge system?

Forget about what you heard. You will need a inexpensive shunt or PWM controller for this small of a system.

[SpaceOddacy]

Awesome, so totally doable.

The power isn't extreme overkill?
Really I would like the batteries maintained while I'm not there so when I arrive during the summer its ready to roll and I wont have to wait to plug in the Engel cooler and can start along with my day.


Answering you're questions.

2-4 day excursions, I wouldn't be in the cabin except to sleep and take a nap so power usage during day time would be almost non existent except for the cooler kicking on for a few minutes.

1 What time of year
2 Location
3 How many watt hours each day you are there.

1. Randomly throughout the year, mainly summer and early early fall.
2. springfield township michigan.
3. I would be spending the evenings in the cabin and time during the day to relax, none of which would require power except for lighting at night, as well as the cooler sporadically throughout the day when it kicks on.

There is no reason to use any parallel battery configuration in this application. It will only add cost, complexity, and maintenance. A single battery string of the appropriate AH capacity is called for.

this simplifies things!

Forget about what you heard. You will need a inexpensive shunt or PWM controller for this small of a system.

Awesome inexpensive is the name of the game!
Powering a small radio for entertainment wouldn't be out of the realm of possibilities with the 350watt panels would it? No sony stereo with 98 speakers just a simple 12v stereo.

[Sunking]

The power isn't extreme overkill?
Really I would like the batteries maintained while I'm not there so when I arrive during the summer its ready to roll and I wont have to wait to plug in the Engel cooler and can start along with my day.

OK a big part of the charge controller job is maintaining the bateries with respect to keeping them fully charged, ready to go, and maximizing their cycle life. But that is only half of the equation. They need your help by maintaing water level and monthly monitoring and preventitive maintenance procedures. So I still need some more information to help you, but here is what i think from what you have said so far:

Keep the bateries at home on a float charger during the off-season so you can monitor and perform PM's. Then at the strart of the season take tehm up to the cabin. Each weekend check them out. Keep a bottle of distilled water on hand at the cabin and home to maintain them. Lastly do some homework on proper batery maintenance and care. This will require an inexpensive volt meter , distilled water, and hydrometer... Easy enough yeah?

2-4 day excursions, I wouldn't be in the cabin except to sleep and take a nap so power usage during day time would be almost non existent except for the cooler kicking on for a few minutes.

1 What time of year
2 Location
3 How many watt hours each day you are there.

1. Randomly throughout the year, mainly summer and early early fall.
2. springfield township michigan.
3. I would be spending the evenings in the cabin and time during the day to relax, none of which would require power except for lighting at night, as well as the cooler sporadically throughout the day when it kicks on.

OK we are getting somewhere now. The light and water problem are no problem. All it takes is a 50 watt panel, and a good 12 volt batery to handle that, with some overkill. Your problem child is the COOLER. Refrigeration is a large power consumer, and it gets expensive. I suggest you invest in a quality ice chest and just take ice up to the cabin with you, otherwise the cooler is going to dig into your pocket book.

With that said i need a lot more info on the COOLER power consuption to advise.

[SpaceOddacy]

Same as the one I will be taking camping when it arrives.

2.5amps 12v so 3amps @ 12v = 36 watts max.

taking the batteries home is a great idea, one I didn't consider!

[SpaceOddacy]

OK a big part of the charge controller job is maintaining the bateries with respect to keeping them fully charged, ready to go, and maximizing their cycle life. But that is only half of the equation. They need your help by maintaing water level and monthly monitoring and preventitive maintenance procedures. So I still need some more information to help you, but here is what i think from what you have said so far:

Keep the bateries at home on a float charger during the off-season so you can monitor and perform PM's. Then at the strart of the season take tehm up to the cabin. Each weekend check them out. Keep a bottle of distilled water on hand at the cabin and home to maintain them. Lastly do some homework on proper batery maintenance and care. This will require an inexpensive volt meter , distilled water, and hydrometer... Easy enough yeah?



OK we are getting somewhere now. The light and water problem are no problem. All it takes is a 50 watt panel, and a good 12 volt batery to handle that, with some overkill. Your problem child is the COOLER. Refrigeration is a large power consumer, and it gets expensive. I suggest you invest in a quality ice chest and just take ice up to the cabin with you, otherwise the cooler is going to dig into your pocket book.

With that said i need a lot more info on the COOLER power consuption to advise.

Id rather have the cooler as I could use it while picnicking around with the family.
Expensive as in the unit itself, slightly but I have heard they last +4\5 years. Not a bad investment if you ask me with how todays manufacturers are making things to break.

[greenHouse]

One alternative that would all you to keep the cooler and not worry so much about the batteries is to use a charge controller that has a voltage-dependent relay. For example, the Morningstar SS-MPPT-15 is a 15 amp MPPT controller that can be configured to enable or disable a "load" relay -- up to 15 amps -- at various voltage set-points.

HOWEVER, you need to be careful with any kind of refrigerator that gets turned on and off, even a solid state Peltier cooler. Warmer air holds more moisture, and when the cooler comes on, it would condense. When it goes off, the moisture would potentially still be in the cooler, then more warm air enters, condenses, mold grows, etc.

Dereck's suggestion that you just get an ice chest is probably best. I'd go one step further and suggest that you make a well-insulated "case" for that cooler so that the chest can maintain temperature with very little loss of ice.

[SpaceOddacy]

the cooler wont be staying at the cabin, cleaning would occur after every trip.

[greenHouse]

the cooler wont be staying at the cabin, cleaning would occur after every trip.

Then I'd get a Peltier (solid-state, electronic, thermocouple, pick your favorite name ...) cooler from a truck stop (they have the best selection and often you get a better price) and wire a cigarette lighter jack to the battery. Pre-cool the cooler in your vehicle on the ride up, then plug in to your system and enjoy a cold one.

The great thing about the MS SS-MPPT-15 is that it will do 12 or 24 volts, and up to 15 amps, so you have flexibility if you later decide to add another panel or three at your fishing camp.

[SpaceOddacy]

Then I'd get a Peltier (solid-state, electronic, thermocouple, pick your favorite name ...) cooler from a truck stop (they have the best selection and often you get a better price) and wire a cigarette lighter jack to the battery. Pre-cool the cooler in your vehicle on the ride up, then plug in to your system and enjoy a cold one.

The great thing about the MS SS-MPPT-15 is that it will do 12 or 24 volts, and up to 15 amps, so you have flexibility if you later decide to add another panel or three at your fishing camp.

I thought that the pelatier module cooled were inefficient?

[greenHouse]

I thought that the pelatier module cooled were inefficient?

That depends. If all you need is a little cooling, an inefficient Peltier may use less total power than a larger, more efficient cooler.

[SpaceOddacy]

*insert homer simpson's face*

[Falcor]

Alternive

Your problem child is the COOLER. .

I have a vacation place we have a 12 volt system but we decided a propane refrigerator is the cheapest and easiest a 10 pound tank will run a gas stove and refrigerator for weeks