# Help with small solar set up



## Karate Kid (Aug 15, 2015)

I realize this would be a pretty small set up. What I am thinking is keeping it small due to my location and if we ever come to a situation I'm concerned about, I don't want to draw attention by having a yard full of solar panels. My first thought was just have a way to charge our two-way radios, then I started thinking flashlight batteries, and then if we could this to power some 12v appliances that could be a game changer compared to using a propane stove. I read Kauboys explanation of the theory of electricity and was really surprised that I think I'm on the verge of understanding it.

Here it is, I would greatly appreciate your thoughts.

2 Pack 12v 35AH batteries

Amazon.com: ML35-12 - 12V 35AH DC DEEPCYCLE SLA SOLAR ENERGY STORAGE BATTERY - 2 Pack - Mighty Max Battery brand product: Electronics

Charge Controller

Amazon.com : WindyNation P30L LCD PWM 30A Solar Panel Regulator Charge Controller 12V 24V 390W 780W + Digital Display +User Adjustable Settings for Off Grid Battery Charging : Patio, Lawn & Garden

Whistler 800w power inverter

Amazon.com: Whistler PRO800W 800-Watt Power Inverter: Electronics

100w solar panel

Amazon.com : Renogy 100 Watts 12 Volts Monocrystalline Solar Panel : Patio, Lawn & Garden


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## PaulS (Mar 11, 2013)

You need 8 batteries and 10 of those panels and you would have a balanced system. 

Why have an 800W inverter when you can't feed it even 150 watts? The maximum watts you will get from your 100 watt panel is 95 watts for the one hour it directly faces the sun. Both batteries in parallel will only deliver 140 watts continuously for a maximum of six hours. It will take the one panel about 9 hours just to charge the batteries.

The 800 watt rating is the output of your inverter. at 120 volts that is less than 7 amps. That will not run a refrigerator or a toaster.

What are you planning on running?


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## paraquack (Mar 1, 2013)

The two batteries combined are like 800 watts of 120 VAC not taking into account loss from the conversion. That's one hour of use (maybe) from your inverter. 
2 golf cart batteries (6 volt at 225 AH) would be 2700 watts (not taking into account loss from conversion) for a little more than double the cost of the batteries you mentioned. $301
Trojan T-105 Deep Cycle Flooded Battery
But you'd need 450 W of solar panel to charge the big batteries in 6 hours or so. With 100 watt panel in would take about 4 days times 6 hours per day.


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## 8301 (Nov 29, 2014)

Expensive but handy and portable. You'd still need the battery and inverter.
Amazon.com: Renogy 100 Watts 12 Volts Monocrystalline Foldable Solar Suitcase: Patio, Lawn & Garden


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## Medic33 (Mar 29, 2015)

you know they have been saying how ineffective solar is cost wise but nothing brings a smile to your face faster than when the electric company is paying you to use their electricity -I have been on grid with an off grid system for almost 10 years now . I like the the fact the company has to pay me the same amount they would charge me for the excess I put back into the grid and yes I had to have a separate meter put on my house. Sometimes it is only 10 or so bucks but I still didn't owe the electric company anything. 
so if you add in how much I would have paid the company( so I am actually using for free + what they pay me back =priceless


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## Medic33 (Mar 29, 2015)

also if you live in area prone to bad storms with high winds blowing snow and flying debris then you better make a cover for your panels and use it.


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## budgetprepp-n (Apr 7, 2013)

If all you are wanting to do is run some small stuff I think a 100 watt panel would be fine.
Now your thinking like a prepper. I would go with a full size battery (or two) 

There is not a thing wrong with having a small set up for when TSHTF


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## Karate Kid (Aug 15, 2015)

PaulS said:


> You need 8 batteries and 10 of those panels and you would have a balanced system.
> 
> Why have an 800W inverter when you can't feed it even 150 watts? The maximum watts you will get from your 100 watt panel is 95 watts for the one hour it directly faces the sun. Both batteries in parallel will only deliver 140 watts continuously for a maximum of six hours. It will take the one panel about 9 hours just to charge the batteries.
> 
> ...


Just the smallest of appliances, two-way radio, and batteries, also might be worth buy a separate battery solar charger for that. I guess something someone would use in their semi while on the road. I think I have seen some type of hot plates capable of cooking a small meal that runs off of 9 amps. I am aware I wouldn't be able to run anything very long and would have to ration what energy this setup would produce. It's either going to be a small setup or nothing at all and I'd rather have something than nothing. I can't be the only house in the neighborhood with running lights and an air conditioner in a grid down situation.


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## Karate Kid (Aug 15, 2015)

budgetprepp-n said:


> If all you are wanting to do is run some small stuff I think a 100 watt panel would be fine.
> Now your thinking like a prepper. I would go with a full size battery (or two)
> 
> There is not a thing wrong with having a small set up for when TSHTF


I was thinking the batteries I linked to were full size, guess not? I've seen marine batteries being used with solar, are those the best choice?


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## 8301 (Nov 29, 2014)

Karate Kid said:


> Just the smallest of appliances, two-way radio, and batteries, also might be worth buy a separate battery solar charger for that. I guess something someone would use in their semi while on the road. I think I have seen some type of hot plates capable of cooking a small meal that runs off of 9 amps. I am aware I wouldn't be able to run anything very long and would have to ration what energy this setup would produce. It's either going to be a small setup or nothing at all and I'd rather have something than nothing. I can't be the only house in the neighborhood with running lights and an air conditioner in a grid down situation.


Hotplate... 9 amps at 120v (1000 watt heating element) That's 90 amps at 12v so you're going to need a bit more battery and inverter.


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## Karate Kid (Aug 15, 2015)

FoolAmI said:


> Hotplate... 9 amps at 120v (1000 watt heating element) That's 90 amps at 12v so you're going to need a bit more battery and inverter.


Another battery then would probably like to have another solar panel? I was thinking I could do this for under $400, but now it sounds like I'm looking at over $600. Maybe this needs a bit more rethinking, perhaps those financial resources could be used better elsewhere. This is why I came here, I don't want to spend $400 on something and only be able to charge my AA's.


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## Kauboy (May 12, 2014)

If you have a 30A charge controller, use that as your middle point and work both ways. First, how many of these panels will max a 30A controller? 100w panel divided by 12v equal ~8amps each. So, 6-7 panels would max your controller. Now, how much actual wattage would you be pushing? 100w, taking into account a ~20% efficiency loss(varies), would make each panel push about 80 actual watts to the batteries. So, 80w a piece across 7 panels would give yield 560 total watts to the batteries per hour. Given that your sunlight will range between 6 and 8 full hours on a good day, that's between 3,360 and 4,480 watts per charging cycle. I would NOT recommend trying to store that much in 35AH batteries(would take about 10). Step up to the big boys. Either marine or golf cart batteries are designed for deep cycling. A 220AH battery can store 2,640 watts of power, so you'd be able to fill up 1 in a day easily, and send the rest to a smaller reserve.
As stated, this still isn't a terrible amount of power. You won't be running anything with a motor or a coil for very long at all.
However, charging low voltage devices and running low wattage LED lights should work fine.
I'd like to point out, all of the devices you would be charging are already DC power(they all use batteries). Instead of taking the power loss from the inverter to go to AC, and then changing back to DC with the charger(transformer), just go straight DC current.
A few resistors can step down the voltage to be safe for your devices, and you can buy 12v LED bulbs online. (just a suggestion)

Honestly, before buying anything, do the math.
Determine the power requirements of all the things you will want to use on this system.
THEN start designing it with all the math worked out.
Power(watts) = Voltage(volts) x Amperage(amps)
Account for some loss due to inefficiency of the panels and you inverter's natural conversion loss to 120v.
It really isn't too hard. Spend a day and you'll get the hang of it.


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## 8301 (Nov 29, 2014)

For a smaller setup like yours Kauboy has the right idea. All your small items that use a USB port to charge up can be hooked to a car type USB charger directly to the 12v battery reducing power losses (about 10% loss) running through a 120v inverter. Bypass the inverter.


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## PaulS (Mar 11, 2013)

YES! for charging batteries stick with the low voltage. You can easily run a charge into your devices with the one panel and a smallish battery. I would get a single battery - deep cycle (think golf carts) with 60 amps or so. The panel can charge that from a six hour discharge in about 7 hours. You will have plenty of power for your batteries.

If you want to run appliances - even a small kitchen appliance - you are going to need a lot more power.


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## Karate Kid (Aug 15, 2015)

Thanks guys, I appreciate the input. I feel like I have learned quite a bit just in the last few days listening to you guys. I'm going to go back to the drawing board and see what I really need and the money I can spend.

Before this, the only thing I ever wanted to know about electricity was, is it turned off before I change out a switch our outlet, but now it's kind of interesting.


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## Dirk Pitt (Apr 21, 2015)

You guys are killing me, I have the Harbor Freight start up kit, which I am playing with and I have one Marine deep cycle battery. That's IT, that is all I have and I am trying to learn playing with that. But all this stuff you guys are talking about is freaking me out! I thought I was doing wonders powering an old car radio.


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## 8301 (Nov 29, 2014)

Dirk Pitt said:


> You guys are killing me, I have the Harbor Freight start up kit, which I am playing with and I have one Marine deep cycle battery. That's IT, that is all I have and I am trying to learn playing with that. But all this stuff you guys are talking about is freaking me out! I thought I was doing wonders powering an old car radio.


Solar electricity can be fun! And I love the ability to supply my own electricity even if it's only to the chest freezer or small window AC.


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