This is my second version of solar power. The first version can be seen in my other instructable
I did not take pictures as I was building this unit, because I had to make several changes as I was building. If I had this instructable would have 100 pages, so I am showing you my almost finished product.
On this first page you are seeing the closed tote. This tote is a Contico 50 gallon tote with locking lid. You can find these at most local home improvement stores. I did a lot of looking before picking this tote. It was the only tote that would give me the space inside and the strength to hold the weight of the components inside.
There are 5 meters in the front, this gives me the ability to know what is going on in an instance. Starting on the left, the first meter is the amp reading of the solar power that is coming from my solar panels. The second meter is the voltage from the solar panels. The third meter, under the lock, is a battery meter just like a golf cart would have showing the battery percentage in 10% steps. Meter 4 is the amperage being drawn from the battery bank. The last meter on the right is the battery voltage level. At a glance I can see the power in from the solar, power out from the battery bank, and how much power is in the battery bank. I got these meters on eBay, so there not the best but they work for what I am using them for. The amp meters are a little off. You can see that the 4th meter, amps from the battery bank, says 0.0. This is not correct, there is really an amp draw of about 0.5 because of the meters are on all the time. The meters wouldn't have to be on all the time, but I wanted them to be on all the time.
This is a partial list of what is in this box. Some of the items I will list are different then what is in my box currently, this is because there are better items to use then what was available to me at the time I built this box. Also everyone has there own opinions and needs for the items in there own box build.
These are the major parts.
- Box that I used. Here
-Batteries that I use, I fit 4 in the bottom of the box. Here
-Inverter. There are lots of options for inverters, the higher the wattage the more and/or larger the items you can run off it. My system is set up for 12 volt battery system, be sure to use an inverter that is made to convert your battery voltage to house hold voltage that you need. Some of these new inverters also have USB charging ports on them. in my box I have these items separate and it take up more space. When I need to replace my current inverter I will get one with more options, like USB ports and a remote power switch. Before purchasing an inverter do some research, there are lots of options. Things such as wattage size, input voltage, output voltage, pure sine wave vs. modified, and many other options.
12 volt to 110/120 volt, this link is just for one brand and there are wattage options.
24 volt to 110/120 volt, another example.
36 volt to 110/120 volt, another example.
12 volt to 220/230 volt, this is for higher voltage equipment.
24 volt to 220/230 volt, another example.
- Solar charge controller. These come in different sizes, voltages, and options. To know what controller is needed you need to know what input voltage from your panels will be and what output voltage to your battery bank is needed. This is an example of a charge controller. Here
- Cooling fans.I have fans installed to help cool the box when needed. Here
- Thermostat for cooling fans. Here
- Voltage meter. These come in different sizes, colors and voltage ranges. This is an example Here.
This is the left hand side. These 2 terminals have a T handle that screws off so that connections to the battery bank can be accessed from the outside of the tote. These connections are not metered through the battery amp meter on the front. I put these connections on for those “what if” moments.
What if I had more batteries?
What if I need high amperage DC, like jump starting a car?
What if the batteries are dead and there’s not enough solar to charge the battery bank and i need to connect a charger?
These connections can be used to put power in, or take it out. Just as if connecting directly to the terminals on a battery. It would be best to use a ring terminal held on with the T handle, but if I needed to use jumper cables I have a set of lugs that screw onto the bolts that look like battery terminals. This way I don’t damage the bolts.
This is the right side. In the middle you see the connections for the solar panels with screw on knobs. These are solar power in only connections.
On the right side the outlet covers say 120 AC. This is a normal outlet just like in your house.
On the left under that cover there are 2 different connectors. One says 12v, it is a port like you have in your car. It’s a cigarette lighter, or accessory port style connection. The other one says USB. Under this cover is 2 female USB ports for charging a USB device. Under the USB ports there is a switch that says USB POWER. The USB ports are not on all the time, they are turned on when needed because converting from 12v to 5v USB uses power even when nothing is connected.
This is the back. What you are seeing is 5 fans. These are small fans that I took out of dead frequency drives. You can find fans like this on eBay or a computer parts store. The left 2 and the right 2 are connected in parallel. Those are connected to a thermostat inside the tote. The middle fan is connected to the solar input. When the panels are producing power and charging the battery bank the batteries produce hydrogen. So to keep the hydrogen from building up in the box one fan is connected directly to the solar panels to keep some air moving through the tote.
This is a view of the upper level. I cut a piece of ¼ inch plywood to make a place to mount everything, and painted it white. Then I hinged it to the back of the tote. You see on the right side all the controls. On the left side is empty space. For now I have a plastic box with extra parts and items to use on the tote. On top the plastic box is a timer controlled power strip, I will use that to control my Christmas lights. There is also a white board that I use to hold the shelf up when I need to work under it.
The last picture is a view of the inside of the lid. In the middle there is a thermostat that controls the fans to remove heat.
This is a view under the shelf. There are 2 batteries under here. I put them in their own battery boxes just in case one of them should leak it won’t damage anything in the tote. I only have 2 batteries now, but I believe that I can fit 3 battery boxes in the tote. If I did not use battery boxes, I believe that I could get 4 batteries in this tote. With these 2 batteries I have 228 amp hours of storage.
The shelf does not rest on the battery boxes; there are 2 shelf supports to hold the front edge. There is a ½ inch gap between the top of the battery boxes and the bottom of the shelf.
This step has the wiring diagrams. I posted an image of the diagram, and also a .dwg file. The .dwg file can be opened with AutoCAD or draftsight. If you don’t have AutoCAD you can download draftsight for free at:
I use draftsight for all my drawings that you see in my instructables.
There are always additions and upgrades that can be done with a system like this. I plan on making a solar panel that will be mounted on the lid of the tote so that if I took this tote with me I would still have a small solar panel.
I would also like to integrate a grid tie inverter. This way when the battery bank is full the extra power can be pushed back into my home to be used. But before I can do this I need more solar panels. There is always work to do……….
Step 7: Updates 3/2/14
This is my additions that i have added, as of 3/2/14.
Up till now when my batteries are full the charge controller would disconnect them and the power from the panels did nothing. I don't like wasting this extra power. When you get to this point you have a few options:
1. Do nothing.
2. Add more batteries.
3. Use the system more.
4. Add a diversion load.
I decided to go with option 4. I added a diversion load controller, a relay, and a grid tied inverter.
-the Grid Tie inverter i got on Ebay.
-the relays, 40 Amp 12 Volt 5 pin, i got on Ebay because i needed multiple relays for other projects also, but you can also get these same relays at an auto parts store.
-the control board I got on Ebay. It is made by Windandsunpower.com at http://windandsunpower.com/Store/Controllers/Other/1URLHVD-12-Basic
- the box that the control board is in i got from automationdirect.com at http://www.automationdirect.com/adc/Shopping/Catalog/Pushbuttons_-z-_Switches_-z-_Indicators/22mm_Plastic/22mm_Pushbutton_Enclosures/SA100SL
- I also put a Watt Meter in so that I can keep track of how much power i have saved. this meter has a setting where you enter in how much your power rate is, then multiples that setting by the power that has gone through the meter. displaying the total on the display.
I decided to go with the diversion load controller setup so i could use all the power that my panels are making. i decided to divert the extra power to a grid tie inverter. what this inverter does is convert the 12 volt DC to 120 volt AC. there is a cord that plugs into a standard 120 volt plug, it then pushes the converted power back into the power grid. I actually plugged the Watt Meter into the wall, then plugged the inverter into that so i have a running total of the power i have saved, and at the time i am writing this i have saved a whole $0.31.
i have seen other people that divert there excess power to a heater in a water tank. others used a heater resistor to heat air. there are lots of things that you can do with this extra power, i just decided to go the grid tie direction.
The addition of the circuit board and relay will eat up a few amps over a years time. if you really wanted to not use any extra wattage up you could always install a switch large enough to handle the amps and manually switch between loads. but to do this you need to always be monitoring your system. to me the trade off of losing some wattage in the automation outweighs the loss of wattage trying to manually controlling your system.
Some of you may be asking how this diversion system works. it is very easy. when your batteries are low they will be charged from your panels like normal. when your batteries are full the control board see's this and switches a relay that is in your positive line from your panels to your charge controller. switching this relay sends power to another device that you choose, in my case the grid tie inverter. when your batteries drop in percent the relay is turned off, sending power back to the charge controller. the control board that i am using has 2 dials to set for switching the relay. one dial sets the point your relay turns on, the other sets the point when the relay is to turn off.
I have added the updated electrical print of how i have things connected. it may be hard to see, so i also added the .DWG file. If you can not open the .DWG file there is a link to a program called Draftsight. its a free cad program.