Don't believe the small Solar panel charging lies!

[gtaus]

I know I'm going to hurt the sensibilities of some good people here on the BYC community, but I am going to tell you what I have learned in my process of educating myself on using small Solar panel kits to recharge something as little as my power tool batteries.

First of all, I was thinking, could I save any money if I recharged my power tool batteries using a small solar panel, like maybe a starter kit from Harbor Freight?

So, let's crunch some numbers I found.

A starter kit for solar panel charging is on sale for $150.00. It would be great to recharge my power tool batteries with "free" solar instead of using grid electricity, right? Well, not so much.

I went online and found out that to recharge my biggest 40v 4Ah battery, at the current electricity grid price of 0.14/kwh, would cost me $0.03 to go from empty to fully charged.

How many times would I have to recharge that battery to break even on the purchase of that solar panel kit?

$150.00 for the solar panel kit/$0.03 grid cost to charge a battery = 5000 recharge cycles

OK. I know this is not going to work out for me. But lets see what the payback period would be....

5000 cycles/365 days in a year (assuming one battery recharge per day) = 13.6986 years!

I really don't average even one tool battery recharge per day, but let's be generous and go with recharging 2 batteries per day because I'm outside whipping the grass, cutting up wood with my battery powered chainsaw, trimming up trees with my reciprocating saw, and maybe running a few battery saws and drills when I am working on a pallet project for the chickens.

5000 cycles/365 days in a year/2 charges per day = 6.8493 years.

That payback period would put me in my 70's. Not a great investment for me. And that assumes the solar panel kit would last 7 years or longer without breaking.

I don't know about the economics of going solar unless you get a massive system up on the roof. Wondering if anyone out there uses these small solar panels kits for anything other than van living or camping?

 

[cavemanrich]

I agree with you totally. The only advantage with solar panels is" If you are living off grid of course. Some peeps live off grid not by choice.
Second advantage would be;;; lets say you have a large spread,, and your chicken coop is a ways from your home/barn. Instead of running 500 feet of cable, to power a small light, or electric pop door, a solar panel will do the job. Consider that running a cable requires it to be buried to be safe. Overhead cable can get tricky, as to the height required to be safe.
If you want a solar panel to power a water heater during winter in your coop??? The 2 things solar, and heater do not come together in same sentence. Of course if you have a LARGE SOLAR PANEL SYSTEM,,,, Yes you can keep your bucket of water from freezing in winter.

 

[gtaus]

If you want a solar panel to power a water heater during winter in your coop??? The 2 things solar, and heater do not come together in same sentence. Of course if you have a LARGE SOLAR PANEL SYSTEM,,,, Yes you can keep your bucket of water from freezing in winter.

Yep, I live in northern Minnesota and a small solar panel with battery would never be enough to keep my metal water fount heater running 24/7.

I have converted most, but not all, of my yard equipment and tools to battery. Still have gas riding mowers and gas snow blower. But I have more or less replaced my gas trimmer, gas walk behind lawn mower, gas (10 inch) tiller and cultivator, and even my gas chainsaw. I use battery powered tools for almost everything. I was hoping that a nice little solar panel kit that I saw in Harbor Freight would be a nice addition to my "going greener" process, but the cost/benefit analysis did not prove out. So, I will continue to charge my batteries on grid power, for only $0.03 per charge cycle.

I have considered using a small inverter plugged into the cigarette lighter port of the pickup to power a battery charger. It would charge up a small 4Ah tool battery without hardly drawing down the much larger 100Ah starter battery. No battery drain at all if driving around at the time the charger was plugged in. Will have to check to see if my 12v auto inverters have auto low voltage cut-offs to protect the starter battery from getting too low. Don't want a dead starter battery at the sake of having charged up a bunch of power drill batteries!

 

[cavemanrich]

@ 3 cents per charge,,, I don't think you are going to add that much to your retirement savings doing the automotive thing.

 

[cavemanrich]

I do have a small power inverter. Not very small but only 400 watt power. Have used it camping when no electricity available at the site, Needed it to run my propane furnace heater in camper. I always took an additional automotive battery for that purpose. When battery ran low, (after few days) I would charge it up by installing it into car,,,, and then go somewhere driving,,, like shopping for groceries.

Just got a bulb lite in my head.
For peeps needing water heated in their distant coop.,, Get a good marine deep cycle battery, and a small power inverter. Plug the water heater,, (mine draws 25 watts) and every few days, bring battery back to get recharged. Of course I would use a cart, or sled to transport instead of carry. For that matter, I would construct a movable box containing my power source.
There is a $$$ amount to pay for this convenience, ,,,, but your chickens will LUV you. and you wont be carrying water that distance few times each day.

 

[cavemanrich]

I have 2 of these plugged in all winter. One for chickens, and other for all other animals, including my feral rescue cats.

 

[gtaus]

@ 3 cents per charge,,, I don't think you are going to add that much to your retirement savings doing the automotive thing.

Well, I already have a couple of 12v auto inverters purchased years ago. They still work. So, no cost to me.

As far as adding a second "house" battery, that is just a thought at this point. We have a pontoon boat and that requires us to get a new battery about every 3 years. The old pontoon battery is still good in many respects, but they lose power when the pontoon is not run for a few weeks or so. We change out the old pontoon battery before we can't get the motor started out on the water. I have at least one of those old batteries from the pontoon that would work great as a second battery for the pickup as long as it was recharged every time the pickup was run.

 

[gtaus]

For peeps needing water heated in their distant coop.,, Get a good marine deep cycle battery, and a small power inverter. Plug the water heater,, (mine draws 25 watts) and every few days, bring battery back to get recharged. Of course I would use a cart, or sled to transport instead of carry. For that matter, I would construct a movable box containing my power source.
There is a $$$ amount to pay for this convenience, ,,,, but your chickens will LUV you. and you wont be carrying water that distance few times each day.

Well, that might work in some areas. My water heater has a 60 watt(?) draw and I think it would burn through a battery in little time. Plus, we currently have about 2 feet of snow on the ground, with more snow falling today, so the last thing I want to do is to have to take out a dead battery during a snow storm and recharge it every few days. I bought a 100 foot extension cord and just lay it on the ground, letting the snow cover it all winter. It's plugged into my GFI outlet on the outside of my house. It will stay out there until probably sometime in April.

Where I live, we typically get a week or two of temps down to -35F to -40F. I don't think I could manage to have a backyard flock in the winter if I did not have my water heater working 24/7. My 3 gallon metal fount water needs to be refilled every 10 days, on average, and I can handle that.

I know some people around here that tote fresh water out to their chickens 2 or 3 times a day in the winter, just to make sure they have some fresh water for a period of time every day. I'm too old for that. So, I bought an extension cord for my water heater.

 

[gtaus]

I have 2 of these plugged in all winter. One for chickens, and other for all other animals, including my feral rescue cats.
View attachment 3351054

I know some people have great success with those open heated dog dishes. But where I live, the Fleet store mainly sells the metal waterers...

And the heated base, which I just see is 125 watts, looks like this....

Well, I guess at 125 watts, running 24/7 in our winters, that would take a really big battery bank and a solar panel kit much larger than the 100 watt starter kit I was looking at Harbor Freight.

FYI, this heater base is used inside my chicken coop. I placed a cement paver on the floor, then put this heater on top of that. The 3 gallon waterer goes on top of the heater base. I'm going into my third winter with this setup. I can affirm that this combination has kept my water from freezing down to -40F inside the coop. I think that is because it is not exposed to the wind and weather outside. They only advertise it to keep water fresh down to +10F, but I have been very, very happy with it keeping water from freezing even when we hit those terribly cold -40F days in the dead of winter.

 

[gtaus]

Just reporting on a real life test of charging one of my outdoor 40v power tool batteries...

I was out today using my new Ryobi 40v power snow shovel. It's only good for small jobs like sidewalk cleaning and decks. But I have also found it useful for tight spots that I cannot use my big gas snowblower.

Anyways, the powered snow shovel has a 40v 4Ah battery. I used it this morning and ran the battery down to 1 bar (out of 4) which is at the point where I usually recharge the battery. Instead of giving theoretical numbers based on the estimated charging time and watts used, I pulled out my Kill-A-Watt meter and plugged the charger into it. Here, then, are my actual results:

Charging time: 1h54mins
Kw used = 0.09Kw
Cost of electricity/Kw = $0.12/Kw
Total Cost to recharge this battery = 0.09Kw X $0.12/Kw = $0.0108

In conclusion, my real-life cost of recharging my 40v 4Ah battery cost me one penny!

Most of my Ryobi batteries are the 18v One+ line, so figure they would cost less than half a penny to recharge in real life. When you look at that aspect of things, we really get a good deal on the energy used with our battery powered tools.

Having said that, it's the batteries themselves that cost so much.

But I still am using some 15+ year old Ni-Cad batteries (not much life in them anymore) and my oldest 10+ year old Li-Ion batteries still hold a good charge. So, I'm not complaining. I use my batteries all the time and would be lost without them.

My initial post was on using a $150.00 solar panel kit to recharge my tool batteries for "free", but at one cent or less to recharge a tool battery on grid power, the idea of putting any more money into "free" energy solar panels seems like a really poor idea.