Solar Powered Air Pump

[Methix]

Hello everyone

I am looking to power an air pump with solar energy. The pump is a Hiblow air pump model HP-80. It runs with AC120V with a power consumption of 71W. The pump needs to run 24 hours a day, 365 days a year in Cleveland, OH. I understand for this to work I will need the following: a solar panel, a charger, a battery, and an inverter. I have found some nice kits online but I'd really like to get the price down by outsourcing each piece of the system. Can any of you recommend any brands and/or websites? Can you also recommend the sizing of the PV system and all it components?

I appreciate any and all help!

[Sunking]

OK 71 watts x 24 hours = 1700 watt hours which means you need to generate 2550 wh/day minimum year round. To do that will require in your location of Cleveland OH:

Panel Wattage = 1500 watts minimum
24 Volt Battery Capacity = 350 AH, Rolls model S460 x 4 units
MPPT Charge Controller = 60 amp, Choose a 60 amp model form this chart
True Sine Wave Inverter = 200 VA minimum. Do not skimp on quality here because you are running a motor load 24 x 7 and a cheap inverter will only burn up the motor and/or the inverter.

If this is a critical mission application you will also need a good quality LPG or diesel 3 Kva generator with a minimum 75 amp 24 volt AC battery charger to get you through 3 or more cloudy days in a row which you get a lot of in Cleveland.

Good Luck.

[Methix]

Thank you for the quick reply , Sunking. 1500W seem like a very large system, doesn't it? Why didn't you include the solar radiance in your calculations?

It turns out that this system will actually be installed in Cabo San Lucas, Mexico. How does this change the sizing of the system? Also, they will have backup power.

Can you also recommend an inverter and a brand of solar panels? There are so many different ones out there!

EDIT: What is MPPT? And how do you know that it requires a 60 amp charger?

[Sunking]

Thank you for the quick reply , Sunking. 1500W seem like a very large system, doesn't it?

No it is bare bones minimum for Cleveland Ohio

Why didn't you include the solar radiance in your calculations?

Solar Insolation was included in the calculation of 1.7 for Cleveland Ohio December/January numbers. [1700 wh x 1.5] / 1.7 hours = 1500 watts

It turns out that this system will actually be installed in Cabo San Lucas, Mexico. How does this change the sizing of the system? Also, they will have backup power.

You clearly stated the system was for Cleveland Ohio. It only changes the Panel Wattage and Charge Controller sizes. Battery and Inverter requirements remain unchanged.

EDIT: What is MPPT? And how do you know that it requires a 60 amp charger?

MPPT = Maximum Power Point Tracking as opposed to PWM controller. The charge controller amps is simple math. 1500 watts / 25.2 volts = 59.5 amps.

[Methix]

Yes, sorry, although I plan on testing this system in Cleveland, it will eventually be installed in Cabo.

So, with a solar radiance of 4.18 in Dec/Jan in Cabo, my calculations give me a solar panel size of 784W and 31.11Amp for the charger. How did you decide on the size of the batteries?

Why is 25.2V the voltage used in calculations for 24V systems? What would be the equivalent for 12V systems? Do you recommend using 24V or 12V systems?

I've noticed that MPPT chargers cost about 4 times as much as non MPPT chargers. How much better do MPPT chargers run? Is it worth the extra cost?

[Sunking]

So, with a solar radiance of 4.18 in Dec/Jan in Cabo, my calculations give me a solar panel size of 784W and 31.11Amp for the charger.

Be careful here because everything depends on charge controller type of being either MPPT or PWM. MPPT uses a 1.5 correction factor, and PWM uses 2. So for you to generate 1700 wh with MPPT require the panels generate 2250 wh, and PWM at 3400 wh

How did you decide on the size of the batteries?

5 times daily watt hours / battery voltage

Why is 25.2V the voltage used in calculations for 24V systems? What would be the equivalent for 12V systems? Do you recommend using 24V or 12V systems?

25.2 is the voltage of a 24 volt system. Going back to your last question: 5 x 1700 wh / 25.2 volts = 337 AH, 5 x 1700 / 12.6 volts = 674 AH It is the Watt Hour capacity of the battery which = Battery Voltage x Amp Hours

I've noticed that MPPT chargers cost about 4 times as much as non MPPT chargers. How much better do MPPT chargers run? Is it worth the extra cost?

Do the math and you tell me. If you use PWM controllers you are forced to use battery panels which are expensive. Use MPPT and you can run at much higher voltages for efficiency gain, lower wiring cost, and use much less expensive Grid Tied Panels. Move your system to Mexico and if you use PWM controller requires 820 watt panel with a 25 (40) amp PWM controller operating at 24 volt battery. Use MPPT controller requires 610 watt panel and a 25 amp (40 amp) MPPT controller. Battery panels will cost you around $3/watt. GT panels will cost you around $2/watt. Do the math, it is a No Brainer.

Since cost seems to be an issue for you you need to ask yourself 1 very important question and be honest with yourself.

If you have commercial power available to run this pump, why do you want to pay 10 to 20 times more for electricity for the life of the project taking it off-grid? I hope you have a good answer to justify it otherwise you are just throwing money away. Battery cost alone are $1800-$2000 every 5 years up front in cash. Well that is not right, batteries will cost you more in 5 years.

[Methix]

I appreciate the thorough replies, Sunking. The company I am working for has had some interest from customers to have solar energy power their air pumps (these pumps are part of our main product). Although the customers have an electricity source in Cabo, it is very expensive and also quite scarce (apparently it cuts out for days sometimes). They are trying to be conscious of their energy usage by looking for a second energy source, and this is where the idea of solar energy came into play. I was assigned to find out if 1) solar energy would be feasible to power the air pump and 2) what it would cost. I absolutely agree with you - looking at the current prices, I do not think that our customers will actually purchase a solar panel system. However, we have also had some interest from other customers that do not have any local power source, and for them the price might just be worth it.

[Sunking]

Although the customers have an electricity source in Cabo, it is very expensive and also quite scarce (apparently it cuts out for days sometimes).

What do you call expensive? What do they charge per Kwh? Solar Battery is going to run you around $2/Kwh right up front in cash with 5 years renewal of batteries.

Have you considered just using AC Charger > Battery > DC Powered Pump. Basically a home brew UPS with or without an inverter. It is a lot cheaper and you can size the batteries to run for weeks if you want or just have a generator on site for extended power outages beyond the battery capacity. Lot's of ways to skin this cat for a lot less expense and more effective than solar.