Now this is an old school schematic. Please feel free to make changes, correction or improvements.

I am going to pick up all the items shown and start pumping my own power at the cabin. Hopefully I can use a table saw and rotozip (at the same time???).

The big question remains 'can I have electric florescent light on the battery system at night (all night???)'.


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Orsen, You have a great schematic, but I have some questions. The day time system is not using any battery power. You will not have enough power from the 45 watt panels to run the inverter. If you are suggesting to run a tablesaw and/or rotozip in the day light mode, you will not have enough power. The table saw will require at least 7-10 amps of power. The night time running of a florescent light will require at least 1.3 amps after start up,( battery output to inverter will be at or near 15 amps at 12 volts)

To put it bluntly you need more power.


Good luck


From what I am seeing, it appears that your panels in the diagram are wired in series, which would be 36v.

Also, the battery polarity is backwards.

 I would hook the inverter directly to the battery. The diagram shows the inverter feeding from the charge circuit. Unless the wire size is stepped up to handle the inverter size/ intended draw from the batteries, that may create an issue as the wires in the kit probably can't handle much more than the 3A max input.

Not sure if that was your intent, that's just what I see in the diagram.

Both of the above comments are very correct, but the word "bluntly: says it all....for your planned device usage, you will need much, MUCH more (battery) battery will not cut it...good try, but try again....

Hi Orson,

I agree with all the statements given.

1.  Redraw both schematics to show the solar panels wired in parallel, not series (as hoopty_yo points out).

2. Redraw both schematics to show the positive output of the battery correctly (see hoopty_yo again).  The long line on the battery symbol is the positive side.

3.  The HF controller will not work without a battery attached.  The "Daylight use only" side of the schematic needs a battery.

4.  Don't think about running both sets of panels with one HF controller.  It won't work.

5.  The 12-volt outputs of the HF charge controller is limited to 4 amps total before the fuse in back blows.

6.  Count on taking at least 100 amps an hour out of your battery to run a table saw.  Charging a battery at 3 amps per hour with the HF kit will take some time to replace 100 amps.  If you need to run a table saw, I would suggest running a generator.

7.  Florescent lights should be run with a pure sine wave inverter unless you use 12-volt florescent lights.  I'm not sure how much light you need at night.  If you need enough to avoid banging into the wall on the way to the outhouse, then the 12-volt lights in the HF kit should work.  If your cabin is to be lit up like a cruise ship you'll need more battery reserve.

A five gallon bucket is capable of delivering five gallons of water, but not if you only put a pint in it.  A 100 amp-hour battery is capable of delivering 100 amps, but only if you put 100 amps into it.  (see 6).

Solar system design always reverts back to the law of conversation of energy.  You can't get more energy out of the system than you put into it.

A 2000 watt inverter at 120 volts AC will deliver about 16 amps, but only if the battery can deliver 166 amps.  (2000 watts/12 volts DC = 166 amps)

And I tried so hard to leave the math alone.

I like old school schematics.  I also like maps instead of GPS numbers.  They both give clarity.

Hillbilly Gene

Hello Orson,


Everything everyone said is correct. The thing I'm gonna add is really about solar itself and how it is usually functions. I'm only speaking about an off-grid installtion, like I think you are trying to achieve.


In your schematic you have the panels in series hooked to a charge contoller with 12v as the input voltage and 13.5v as the output. Then the lines run directly to an inverter  with or without a battery (night \ day setup). As others have pointed out. This will not work the way you are laying it out.


Solar panels, on the scale that you are looking, are really just a battery charger. Everything you run, day or night, runs from the battery. Your panels are charging that battery as you drain it by running items. If you are running the saw or the lights they are running from the inverter which is pulling the power from the battery. The panels are then trying to put the power back in the battery. If you are taking the power faster than the panels can put it back, your saw or lights will quit working until your battery is charged once again.


The three panel kit (standard 45w kit) will provide 2.5 - 3 amps while in direct sunlight during the high points of the day. They will not provide that same power all the time the sun is out. The power output drops as the sun intensity drops.  You can look up your particular location to determine how many hours are considered peak solar hours. So with your three panels you will provide 3 amps, which is just above a standard trickle charger, to your battery for "X" amount of hours a day. If your saw takes 7 amps to run it, you are draining the battery at double the rate you are charging it. This is why most people have a multiple battery bank. So they can provide the power for the length of time they want to work. They also match the amount of panels they have charging that bank to how large the battery bank is.


The power into the charge controller from the solar panels would not be at 12v. The open circuit for these panels is around 20 - 21 volts... the actual charge voltage is more around 14.5 - 17 volts.  Once this voltage goes into your charge controller it will reduce it to the voltage required to charge your batteries. Usually it is 13.5v - 14.1v to charge a 12v battery, so this is what the charge controller steps the power down to. If you were to connect the charge controller directly to an inverter, the inverter would not be able to power anything. The voltage is correct, but the inverter would draw more amps than your panels are providing, this is why it needs to be connected to a battery.


These solar kits can power some items directly, but we are looking more on the scale of the fans that were used for the attic vent in other thread. Something that has very low draw of amps.


If you are to power a cabin or workshop.. you will need some power storage aka batteries. You will create power with the solar panels, but you need to save it up so you can use it on the bigger items when you want to run them. Then when those power tools are at rest, the solar panels are refilling your batteries so you have power when you want it again. The more panels, the faster it will refill your storage.


Sorry I'm so long winded.. and I started to drift a bit. It is harder that I thought to keep on topic.. and keep it easy to read.




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