(2) 120 Solar Panels & 20Amp Controller...Now What?

[milezone]

Hi Guys,

Yes I am very new at this and want to make sure to install my newly coming system correctly.

1st: I am trying to completely run our water pump and a couple lights with a 240 watt solar system. We live in country so have well water. So I purchased (2) 120 watt solar panels from UL Solar, and a 20amp charge controller.

1. How many batteries do you suggest, or how much amp's?

2. Do I run the batteries and keep 12 volt system, or do I turn it to 24 volt, or does that even matter?

3. Can a Inverter be installed so it runs consistantly? Our well pump house is in back yard, so do not want to have to turn on each time we need water. Just want the inverter to always be running and of course pump will kick in when we turn on faucets.

4. I suppose I should install a fuse box, which I am guessing is installed between the solar panels and the Charge Controller? If so what size fuse is recommended?

5. Any other tips greatly appreciated.

Thanks guys and sorry for the many noob questions.

Milezone

[milezone]

Well I guess I asked too many questions, no one seems to want to respond. Maybe I asked the wrong questions?

[Sunking]

1. How many batteries do you suggest, or how much amp's?

The delay in response is because you are going about this wrong way and have not provided the info needed to help you out. You made a very common mistake, you bought something and hope it works. For a solar battery system you have to determine how many watt hours you need in a 24 hour day, then you need the location. So the answer to your first question is almost impossible to answer other than to say at 12 volts with a 240 watt panel system you need a need a 20 amp MPPT controller and up to 300 Amp hour battery.

2. Do I run the batteries and keep 12 volt system, or do I turn it to 24 volt, or does that even matter?

Depends on what size load device you are running. Since you mentioned a water well I assume you will need either 120 or 240 AC for the pump. How much power does the pump need? The higher the voltage the more efficient

3. Can a Inverter be installed so it runs consistantly? Our well pump house is in back yard, so do not want to have to turn on each time we need water. Just want the inverter to always be running and of course pump will kick in when we turn on faucets.

It can but it cost you energy, and with such a small system you do not have much power to spare

[milezone]

Thanks for the reply, this is what I need to get started, just a response.

I live in SW Kentucky, the pump is 4.5 amps, pumps out water about 100 feet down. It is 120V.

I currently have 3 batteries that are 105 amp batteries each. I have 2 120 watt panels, and 1 60 watt panel. I live on 1 acres and will place these on my garage roof which is open to sunlight.

Is there an inverter that is recommended that will run at "sleep" mode when not needed and kicks on when the need for power kicks in?

So you are recommending I go 24 volts? Is my system not enough to do this job? Thanks

[Sunking]

I live in SW Kentucky, the pump is 4.5 amps, pumps out water about 100 feet down. It is 120V.

Do you have any idea about how long the pump runs each day? Sounds like you have a 1/2 hp well pump

I currently have 3 batteries that are 105 amp batteries each. I have 2 120 watt panels, and 1 60 watt panel. I live on 1 acres and will place these on my garage roof which is open to sunlight.

The 60 watt panel is not of any real use and will rob you blind of power. There is just no configuration you can put it in to be compatible with the 120 watt panels. Depending on the actual specs and how configured you solar panel wattage could end up only being 100 watts when you expected 300 watts. Only good way to use it is to give it its own charge controller.

Is there an inverter that is recommended that will run at "sleep" mode when not needed and kicks on when the need for power kicks in?

So you are recommending I go 24 volts? Is my system not enough to do this job? Thanks

There are quite a few inverters out that have sleep mode... I think 24 volt would be best, but right now you do not have the batteries to run 24 volts. Well you do if you only use 2 of the 3. You would need a 4th battery however your solar panel wattage is too low to support 24 volt @ 200 AH

[milezone]

I am really not too sure how much it runs per day, but really only gets used for 2 of us for a nightly shower, and the normal cloths washing, etc. etc.

So is it possible if I purchase a 4th battery, and then go 24 volts? Or will I need to get another solar panel to have 3 120 watts hooked together?

Or do I stay with 12 volts for now until I do indeed get a 3rd and 4th battery? Just weighing all my options. I am really not too sure how to wire the solar panels to make 24 volt. I understand how to do that with batteries, just not sure with solar panels, or does that part matter?

BTW thanks for all your help.

[Sunking]

OK using an educated guess I assume the pump runs 1 hour or less per day, which means about 500 watt hours per day. Your December Solar Sun Hour Day is 2.5 hours. So based on that using a MPPT controller you would need a 300 watt solar panel with a 25 amp MPPT charge controller with a 12 volt battery. You have 240 watts, and since I doubt the pump actually runs 1 hour per day 240 watts should work OK. December and January might be a problem, but I doubt it.

As for battery voltage and capacity based on 500 wh daily usage requires a a 2500 watt hour reserve capacity. So at 12 volts you would need 2500 wh / 12 volts = 208 AH, or 104 AH at 24 volts. So with that said all you need is 2 of your 12 volt @ 100 AH batteries configured either 12 or 24 volts.

Caution:

I calculated assuming you will use a MPPT controller. If using a PWM controller you will need more solar panel wattage to make up for the low efficiency of a PWM controller. If you use a PWM controller your panel wattage jumps up from 300 watts to 400 watts.

[Mike90250]

You will need a "pure sine" or "true sine" wave inverter. Modified sine or square will rapidly burn out the pump motor.

You also will have to supply the starting surge needed by the pump, and the starting surge can be 10x the running power. Most inverters can only supply 2x or 3x as a starting surge, so you may need to greatly oversize your inverter, just to start the pump.

Many well pumps are dual voltage, and can run 120/240 by just swapping a jumper on the pump.

[milezone]

Thanks guys, that's some great information. I am glad I am on track for the right equipment needed. Now if you do not mind a few more questions.....

1. What is a MPPT Controller, and why is it different than a PWM, and how the heck do I know what I am using?

2. So is the rule of thumb (in my case) for each 120 watt panel, I should have 1 battery (100 amp)?

3. Do you have a good source for me to purchase a Pure Sine Inverter that has the power saving "Sleep Mode" feature?

4. The plan is to add a new 120 watt panel every 6 months, and eventually add a line to run to the house and use "green plugs" to start running lights, small appliances, etc, as the system grows.

I really appreciate the help guys, very helpful.

Milezone

[Bala]

Re charge controllers, there is a sticky thread at the top in the off grid section that may be off help

[Mike90250]

1. What is a MPPT Controller, and why is it different than a PWM, and how the heck do I know what I am using?

2. So is the rule of thumb (in my case) for each 120 watt panel, I should have 1 battery (100 amp)?

3. Do you have a good source for me to purchase a Pure Sine Inverter that has the power saving "Sleep Mode" feature?

4. The plan is to add a new 120 watt panel every 6 months, and eventually add a line to run to the house and use "green plugs" to start running lights, small appliances, etc, as the system grows.

Charge controller FAQ http://www.windsun.com/ChargeControls/ChargeCont.htm
MPPT Controller info http://www.windsun.com/ChargeControls/MPPT.htm

Before you purchase a charge controller or sine inverter, you need to "size" your system for your loads. If you get a small controller, and keep adding panels, you will outgrow your controller, and have to buy another. If you find an inverter on ebay cheap, what do you do when you discover it wont' start your well pump.

Plan on at least a 24V system, that will 2x batter for starting surges than a 12V system. You need to get an accurate measurement of your pump's starting surge, may cost you an electricians visit and have him use a "peak hold amp meter" to measure starting surge, then you have a # to use for shopping for a inverter..

I like http://www.solar-electric.com/inverters.html for inverters, they've been in business for a long time, have a brick & mortar store, and good prices. But you need to know the size before going further.

And, I'll ask - why all the expensive solar stuff. if you need water for a blackout, a small genset will run a long time on $500 of gasoline (1 solar panel)

[milezone]

Charge controller FAQ http://www.windsun.com/ChargeControls/ChargeCont.htm
MPPT Controller info http://www.windsun.com/ChargeControls/MPPT.htm

Before you purchase a charge controller or sine inverter, you need to "size" your system for your loads. If you get a small controller, and keep adding panels, you will outgrow your controller, and have to buy another. If you find an inverter on ebay cheap, what do you do when you discover it wont' start your well pump.
Found out our well pump is 240 volts, so guessing solar is out for that. But I have already hooked up the panels, and even have some plugs hooded up. Running garage lights, radio, and a few other things. Works just fine, and charges batteries each night.

Plan on at least a 24V system, that will 2x batter for starting surges than a 12V system. You need to get an accurate measurement of your pump's starting surge, may cost you an electricians visit and have him use a "peak hold amp meter" to measure starting surge, then you have a # to use for shopping for a inverter..
Yes i think I will convert to this when I reach 6 panels, right now "tinkering" in the garage with my 2 120 watt panels.

I like http://www.solar-electric.com/inverters.html for inverters, they've been in business for a long time, have a brick & mortar store, and good prices. But you need to know the size before going further.
Thanks will keep that site handy
And, I'll ask - why all the expensive solar stuff. if you need water for a blackout, a small genset will run a long time on $500 of gasoline (1 solar panel)
After that $500 in gas is gone, then what? Another $500. I thought solar was the way to go to be energy independant in the long run, help when power does go out, and top it off with being green. Appreciate all the help guys.

[john]

Hello there, I was where you are two years ago.I bought stuff (2 120 watt panels ,4 100ah batteries) and hoped it would work.It does, I am learning all the time,and sure I bought some stuff I didnt need or was crap ( I now have 5 inverters),but I am doing my washing machine for free. According to the experts I am way underpowered, and it should not work, but it does. Keep experimenting,you will figure it out.
Since we have basically the same system I will tell you what little I know. I now suffer from lowering voltage. My batteries when full read 13.00 volts when full. Two years ago it was 13.22.I am not putting enough amps into my 4 batteries (at least 6-7). I need another panel.
Inverters are tricky. You always need a bigger one than you think. To run my washer (700 watts) I tried a 1000 w inverter(200w surge). Didnt work .Had to use a 2500.
Pure sine inverters are the best.Power is just like the house power. Modified sine (square wave) is a little fussier.I ruined my drill battery charger. Good luck