Hey guys,

Just built a shed and was deciding wether I would run power to it or not. All I really need is a light and maybe a plug for a radio..

I was thinking instead of running power maybe it would be fun to build a small Solar system to to power a battery that would power a LED light.

Is it complicated? Anyone have good resources? Can it be done for less than 300-400 bucks?

 

I have a solar powered boat on my pond. I have a 100ah sealed battery that is charged by a 5 watt solar panel. The panel is small enough in relation to the battery that a charge controller is not needed. And since the boat may go unused for days or a week at a time it's plenty of time for the 5 watt panel to charge the battery.

Since my system is pretty simple I just got the solar panel off Amazon though others like Northern Tool and many others also carry them. The first thing you need to do is come up with how much power you will need. Saying a light and radio is one thing but you have to know how much wattage they use. Then you need to estimate how much you will use those items and how long between uses. Then you can figure how big a battery and solar panel you will need.

 

Ok I guess I have to do a bit of math and figure a few things out here. I'll be back.

 

When I built my shed how I wished I had power to work with. So I ran an underground line and put in a light and outlet. After I built the shed I hardly ever need it. Needed it to build it but didn't need it after it was built.

 

Depending on how far the shed is from utility power solar may make no economic sense whatsoever.

 

I have a small solar system in my shed. It uses a battery similar to a motorcycle battery. I have a fairly bright 12vdc LED ceiling light and a 12vdc fan on a thermostat.

It's been working for several years with no problems.

 

It's not so much about economics and more about can I do it. Im interested in learning about it and doing a small project like this seems like a fun way if it doesn't cost a small fortune

 

Well, of course it can be done and only you can determine if the costs are acceptable.

I have a long thread going about my project of making a battery-operated riding lawnmower. The project long ago became economically unfeasible but I persevere because I want to see it come to fruition. I justify it, if only to myself, that it is still cheaper than therapy and it keeps me out of bars and away from loose women.

There is absolutely nothing wrong in doing a project for your own satisfaction, regardless of the cost. Sometimes it is the only thing keeping us sane in this insane world.

 

My pond boat has been in use for six years. It's a wonderful setup. Anytime I want to use it I just jump aboard and go. There is no battery charging or worrying that the battery is dead. Even a simple and inexpensive system like mine can work very well. You may find the same with your shed. A LED light or two and a radio is very doable for a reasonable price.

My old XM satellite radio boom box consumes about 100 mah at 12 volts when on a reasonable volume. A more modern radio may have lower consumption. LED lights will be easy to figure their needs.

 

A kerosene lamp or a Coleman gasoline lantern would give probably about the same amount of light and a battery operated radio can last a long time on a battery.

 

So was looking at a few accessories Id consider power from the shed. The radio I use says 16 watts, a led bulb... Maybe my
chargers for my power tools. They don't say watts on them. But i think it's amps x volts right? So 180 watts and and my other charger is 110.

 

The chargers for your tools could be a problem or at least they will drive the cost and complexity of the system up a bit. A radio and lights are easy to do on DC and you could get away with just a battery and solar panel.

Your chargers are AC and some only work with pure sine wave AC. My old NiCad Dewalt chargers work ok on cheap inverters but my all of my Bosch lithium chargers require a pure sine wave. Most/all inexpensive DC to AC inverters generate a chopped or stepped AC wave form. Pure sine wave inverters are available but they are more expensive.

The other problem with your charger idea is that you tend to just plop a battery into the charger and forget it. That means the charger may be left running continuously which puts a constant drain on your solar system. It could reasonably work if you only charged when you were in the shop and remembered 100% to unplug the chargers when they are not actively charging. Unfortunately all it takes is forgetting one time which could discharge your solar system battery completely leaving you with no power in the shop and possibly damage the main storage battery.

 

Ok the more I think about it the more I'm likely going to just go with a solar motion light for lighting inside. For the few times I'll need power I'll run an extension cord for now.

But this is still a project that interests me enough to take on down the road. So lets play the what if game if you guys don't mind answering questions.

So adding up all the watts for all items if they were to be used at one time (16 for radio, two led bulbs @ 10 watts each, 180 for dewalt charger and 110 for rigid) I get 326 watts.

Now I read some where that you loose 20% through the system? So Does that mean I need panels that are capable of generating 20% more than my max? bringing me to 391 watts?

So a couple of these

Upsolar 260 W Poly Solar Panel UP-M260P

Now if I want to run AC electronics I need a sine inverter right?
Something like this?

Samlex PST-600-12 600W 12V Inverter

I guess I need a charge controller for the batteries.. Something like below.

Morningstar Remote Meter RM-1

As for batteries. How does one determine the amount of batteries needed? I guess you would use deep cycle batteries? Would you use lithium or lead acid? Whats the pros and cons of both?

Thanks for the discussion guys.

 

There is no single number for efficiency loss. That will depend on the individual components you choose. Staying with DC for everything eliminates a big loss and that's an DC to AC inverter.

Before you can figure how much battery you need you need to estimate how long you want to use your devices between charges. Basically figure how much you will take out of the battery between charges.

Then you need to estimate how long the rest/charging period will be between uses. That will tell you how much solar panel capacity you need in order to recharge the battery between usages.

One key thing to remember is that most solar cells rating is their absolute best under laboratory conditions simulating noon at the equator when the sun is directly overhead. You will never achieve it. Canada is north of 42 degrees so even at noon on the first day of summer the sun is nowhere close to directly overhead. Then every time other than noon on the first day of summer you will get even less out of the solar panel. Down here in the middle of the US I'd use half as a good guesstimate but up there you could get even less.

Using lithium batteries will open a whole new series of problems and raise the level of difficulty significantly. That is why most solar systems still use old fashioned lead based batteries. Usually deep cycle. I use sealed telecom batteries. They are what the phone companies use to back up their systems during power outages. They are expensive but very good. Most people use wet deep cycle batteries.

 

Thats a good panel... Since its a 30 volt panel you want an mppt controller... That controller turns the extra volts into amps.. You will get charging at first sun over a PWM charger...

You can get close to 20 amps out of that panel..

I have a similar panel as I use it for my camper...

Since you can treat your shed like a camper I would suggest that panel for one...

Then dollar for dollar I would get this controller.. It works well..

ECO-WORTHY 20A MPPT Solar Charge Controller 12V/24V |Eco-worthy

To power your stuff I dont think you need an expensive pure sinewave inverter.. I use the small cigerette lighter type that are 120 watts to power the tv in the camper.. A Box fan and to charge cell phones/ipods etc...

These peak units work well.. Ill be upgrading the camper to the 1200 watt model soon.. ( My goal is to power the whole camper. I will plug the camper cord into the invertor.)

PEAK 800-Watt Mobile Power Outlet-PKC1M08 - The Home Depot

Next batterys...

To start off with what your doing I woold get two 6 volt golf cart batterys from sams club.. Other warehouse stores cell them too.. ( Hook them in series)

This will get you 230 AH.. You only want to drain deep cycle batterys 50%.. So your 230 AH becomes 115 AH..

I think your 326 watts converts to 27 amps @ 12v.. So you can run all your stuff at the same time for about 3-4 hours before you need to recharge the batts..

These batteries are about 85 bucks each..

Duracell® Golf Car Battery - Group Size GC2 - Sam's Club


This should get you going to a similar set up as I have ...



Hope this helps...

 

Cell phones and TV's are one thing. Many cordless lithium tool chargers require a pure sine wave. I would check whatever tools you have and see if they need it before buying an expensive sine wave inverter.

One benefit of a pure sine wave inverter is they tend to be more efficient. You'll have to figure is the added cost of that efficiency is worth it.