Stand alone solar panel for single building

[MrDee]

I am in the process of building a new garage. I would like to start my introduction into a solar panel energy source, however, though I have read up on these systems, most of it is still Greek. I want to run my garage door opener and two shop lights and a couple of electrical outlets. I would like to find out how many panels I would need and what else I would need to complete this project. Anyone?

[Sunking]

You need to determine how many watt hours per day you need is the very first step.

Basically you need solar panels, charge controller, battery, hardware, and inverter. Battery systems cost right about $3/watt hour, plus about $1/wh battery replacement every 5 years.

[charles]

can i buy grid tie inverter for stand alone solar system( off grid ) use?

[Sunking]

can i buy grid tie inverter for stand alone solar system( off grid ) use?

No sir.

[MrDee]

Response questoin to Sunking

You need to determine how many watt hours per day you need is the very first step.

Basically you need solar panels, charge controller, battery, hardware, and inverter. Battery systems cost right about $3/watt hour, plus about $1/wh battery replacement every 5 years.

Not quite sure how to do that, I am assuming you mean how many watts the garage door opener uses when it is in operation? Otherwise the unit is in down mode and does not use any energy. As far as the shop lights go, only when I would need them maybe an hour or two per day. The outlets if I needed to hook up a room heater or drop light once in a while. Is there a site I can access that talks about battery systems and the cost of a charge controller, battery hardware and inverter?

[Sunking]

I am assuming you mean how many watts the garage door opener uses when it is in operation?

No sir. that is is only half the equations. Watt Hours = Watts X Hours. Tough formula huh?

The outlets if I needed to hook up a room heater

Room heater or any other large wattage item will never happen, you cannot afford it. A very small foot warmer type of heater uses 1500 watts, and only used in winter when days or short. You garage is not large enough to hold the batteries required. If you used say a 1500 watt heater for say 2 hours = 1500 watts x 2 hours - 3000 watt hours which is very little electricity. Battery systems are very inefficient of around 50% so the panels need to generate about 6000. If you live in some place like Kansas City with decent winter isolation of 2.9 hours you would need 6000 wh / 2.9 h = a 2100 watt solar panel array, and about 1000 pounds of battery. That may not mean a lot to you, but you will understand money and to build that kind of system in KCY that generates 25 cents worth of electricity per day will cost you about $6000 with $2000 of that in battery cost that has to be replaced about every 5 years.

Keep in mind what I said earlier, it will cost you roughly $3000/Kwh to install off-grid solar.

Is there a site I can access that talks about battery systems and the cost of a charge controller, battery hardware and inverter?

Sure just GOOGLE solar power equipment suppliers.

Now with all that said you can reasonable install a system that will handle you garage opener and a few small lights for occasional use. Actual size depend son where you live and how much power you want to use in a day. For a garage door opener and a few lights you need roughly, a 100 watt solar panel, 10 amp charge controller, 12 volt 100 AH AGM battery, and about a 500 watt inverter. Inverter size will depend greatly on how large the motor is in the opener.

[russ]

If you want heat solar thermal is a better choice for that portion of the application.

Solar thermal water panels or solar thermal air are both far more efficient than solar PV - more or less 3 times the efficiency of solar PV.

One step back - daylighting (use of natural light) and insulation are an essential ğart of any solar system. Both are far cheaper than adding solar PV panels.

[MrDee]

Garage Door Opener

No sir. that is is only half the equations. Watt Hours = Watts X Hours. Tough formula huh? Room heater or any other large wattage item will never happen, you cannot afford it. A very small foot warmer type of heater uses 1500 watts, and only used in winter when days or short. You garage is not large enough to hold the batteries required. If you used say a 1500 watt heater for say 2 hours = 1500 watts x 2 hours - 3000 watt hours which is very little electricity. Battery systems are very inefficient of around 50% so the panels need to generate about 6000. If you live in some place like Kansas City with decent winter isolation of 2.9 hours you would need 6000 wh / 2.9 h = a 2100 watt solar panel array, and about 1000 pounds of battery. That may not mean a lot to you, but you will understand money and to build that kind of system in KCY that generates 25 cents worth of electricity per day will cost you about $6000 with $2000 of that in battery cost that has to be replaced about every 5 years.

Keep in mind what I said earlier, it will cost you roughly $3000/Kwh to install off-grid solar.

Sure just GOOGLE solar power equipment suppliers.

Now with all that said you can reasonable install a system that will handle you garage opener and a few small lights for occasional use. Actual size depend son where you live and how much power you want to use in a day. For a garage door opener and a few lights you need roughly, a 100 watt solar panel, 10 amp charge controller, 12 volt 100 AH AGM battery, and about a 500 watt inverter. Inverter size will depend greatly on how large the motor is in the opener.

Thank you Dereck for that infor: It's a 1/2 horsepower motor with about 375 wh. If I did the calculations correctly that equates out to about 5 watts per use. So if I average opening and closing the door on average of 4 times per day, so I figure about 20 watts per day usage(?). If I am correct in my thinking, do you know of a place where I can purchase a complete solar 75-watt panel kit?

[Mike90250]

The door opener also has a radio and other electronic circuits inside. My opener, idling, pulls about 20 watts, 24/7 That ends up being a lot more power than the motor uses.

[Sunking]

It's a 1/2 horsepower motor with about 375 wh. If I did the calculations correctly that equates out to about 5 watts per use. So if I average opening and closing the door on average of 4 times per day, so I figure about 20 watts per day usage(?). If I am correct in my thinking, do you know of a place where I can purchase a complete solar 75-watt panel kit?

No your math is backasswards. The motor uses 375 watts, and if you use it say 5 minutes per day it uses 375 watts x .083 hours = 32 watt hours.

However there are a couple of catches. In order to drive a 500 watt inverter, you will need at least a 12 volt 100 AH AGM battery. To properly charge a 12 volt 100 AH battery using a PWM charger will require at least a 100 watt or more solar panel. Yes it is overkill, but the problem is you are driving a rather large wattage motor. With that you will have enough to run a few lights OK. Only problem is a 500 watt inverter may not be enough to drive a 1/2 hp electric motor, you may need a 1000 watt inverter.

[johncslee]

No your math is backasswards. The motor uses 375 watts, and if you use it say 5 minutes per day it uses 375 watts x .083 hours = 32 watt hours.

However there are a couple of catches. In order to drive a 500 watt inverter, you will need at least a 12 volt 100 AH AGM battery. To properly charge a 12 volt 100 AH battery using a PWM charger will require at least a 100 watt or more solar panel. Yes it is overkill, but the problem is you are driving a rather large wattage motor. With that you will have enough to run a few lights OK. Only problem is a 500 watt inverter may not be enough to drive a 1/2 hp electric motor, you may need a 1000 watt inverter.

hahaha backasswards. i love reading posts that has to do with watt and watthours, i felt the same confusion when i first tried to understand these terms...

[Sunking]

hahaha backasswards. i love reading posts that has to do with watt and watthours, i felt the same confusion when i first tried to understand these terms...

It is really simple to understand. If you earn $10/hr how much money do you make in a day, week, year?

[johncslee]

its more of the term wattxhour that confused me. now i just think of it as joules = 3600 watthour

[Sunking]

its more of the term wattxhour that confused me. now i just think of it as joules = 3600 watthour

Joules is a measurement of mechanical energy. For example lifitng x pounds, y feet, in z time. It can be converted to electrical energy minus heat and friction losses.