Inverter to Battery

[SunEagle]

Ooh ok. Can i add a 20Wp panel paralel to 50Wp panel??

If the Vmp for the 20watt is within 5% of the Vmp of the 50watt you should be ok.

The Imp for those 2 panels will just add up but the Vmp will average out between the 2 panels and will reduce the output of the panel with the higher Vmp rating.

[fivewin]

Ooh ok. Can i add a 20Wp panel paralel to 50Wp panel??

[SunEagle]

Thank you @SunEagle.
i still have a 50wp panel left and a 10amp CC. Lets say that i use the pump 1 hour every day ONLY after peakhours this 50Wp system with 40Ah agm should do i think. Im able to pump 600-800 liters of water to my watertank and thats more than enough for me.

Depending on what the Imp rating of that 50w panel it may be a little small for a 40Ah battery. You need about 1/10th the Ah rating to charge an FLA type battery. For the 40Ah that would be 4 amps. You can get away with 1/12th the Ah rating or ~ 3.33amp of charging but run the risk of not getting the battery charged back to 100% each day.

[fivewin]

Thank you @SunEagle.
i still have a 50wp panel left and a 10amp CC. Lets say that i use the pump 1 hour every day ONLY after peakhours this 50Wp system with 40Ah agm should do i think. Im able to pump 600-800 liters of water to my watertank and thats more than enough for me.

[SunEagle]

So, how much Ah (single)battery i need then (without connecting to a solar system) to run a 75watt ac waterpump for for example 1 hour and what is the minimum watt inverter i have to use?? Assuming that the battery is fully charged ofcourse.

A 75watt ac load for 1 hour is 75wh. Using a 12volt battery you would need a battery around (75wh / 12v x 4 = 25Ah). The DC to AC inverter could be as small as 150 watt.

That battery will allow you to discharge it 25% to get your 75wh give or take and you will need at least 3 amps of charging so about an 80watt panel and 10amp PWM CC should complete the system. If you run a bigger pump or for more hours you will need a bigger battery and solar panel wattage.

[fivewin]

So, how much Ah (single)battery i need then (without connecting to a solar system) to run a 75watt ac waterpump for for example 1 hour and what is the minimum watt inverter i have to use?? Assuming that the battery is fully charged ofcourse.

[SunEagle]

Complete BS.

A 12 volt 7 AH battery cannot run a 75 watt load. The math is impossible.

Actually it did run for about 30 seconds and then I heard a "beep" which I think was the inverter shutting down due to low battery voltage.

[fivewin]

Im now testing a sanyo pump ac220v 50hz 125watt.
i use a NEW fully charged 40Ah agm battery and a 500watt inverter. i did not connect to solar panel and chargecontroller. The pump will not start and the inverter beeps and red light is burning.

does it mean i need a bigger inverter or bigger battery???
its my intention to use such a pump for 1-2 hours per day only.

[Sunking]

Thanks for the expl Sunking. Im wondering what the minimum Ah needed (battery) for that 75w pump??.

depends on how many hours you run the pump each day. I can tell you how to calculate it.

Watts x Hours x 5 / Battery Voltage.

Example you want to run the pump 10 hours and use a 24 volt battery:

75 watts x 10 hours x 5 / 24 volts = 150 AH. 200 pound battery.

[fivewin]

To be specific, i want to run that 75watt pump 1 hour during peakhours and 1 hour in the evening to fillup my watertank.
in theory i will use 150 watt/hours. What is the minimum Ah battery i needed to use in the evening?? That pump needs more wattage to startup i think.

[fivewin]

Thanks for the expl Sunking. Im wondering what the minimum Ah needed (battery) for that 75w pump?? I think that guy on youtube can not run that pump in the evening with such a setup.

[Sunking]

If i connect my inverter directly to battery and i have load during the day when the battery is also charged what happend??

will the battery also be charged when there is a load??

Real simple, if the system is designed right it works.

Let's say you have a 50 watt load and run it 24 hours per day (1200 watt hours) with a 4 Sun Hour Day. You would need:

12 volt 500 AH 300 pound battery.
450 watt solar panel
40 Amp MPPT Charge Controler

It would run 24 hours a day no problem. When the sun is out the panels generate enough power to run the pump. plus recharge the batteries to run all day and night. It is really simple math when you think about it.

• A 50 watt load uses 1200 watt hours in 24 hours (50 watts x 24 hours = 1200 watt hours)
• The panels must generate 1.5 times the amount of power you need in a day on the shortest day of the year. So 1200 watt hours x 1.5 = 1800 watt hours.
• If you have only a 4 Sun Hour Day and need to generate 1800 watt hours then you need 1800 watt hours / 4 Sun Hours = 450 watts.
• 450 watt panel with a MPPT Controller into a 12 volt battery delivers 450 watts / 12 volts = 37.5 amps, so you need a 40 amp controller.

5th grade math.

[Sunking]

Thanks for your reply. I saw a youtube whereby a guy claims he can rum an ac pump 75watt with an 300watt inverter and a 7Ah battery. If this is not a hoax its ideal for me.https://m.youtube.com/watch?v=hFTF1HjPihs

Complete BS.

A 12 volt 7 AH battery cannot run a 75 watt load. The math is impossible.

[Wy_White_Wolf]

If i connect my inverter directly to battery and i have load during the day when the battery is also charged what happend??

will the battery also be charged when there is a load??

If the load is greater than the array output then the battery will discharge as it needs to make up the deficiency.

If the load is smaller than the array output then the battery will be charged if it needs to be.

WWW

[SunEagle]

Thanks for your reply. I saw a youtube whereby a guy claims he can rum an ac pump 75watt with an 300watt inverter and a 7Ah battery. If this is not a hoax its ideal for me.

https://m.youtube.com/watch?v=hFTF1HjPihs

You can charge a battery while it is being used but if the battery is too small you might drain it below 50% SOC if your panel does not provide you enough to keep it charged.

In the case of that video I would say he is taking a chance of killing that little 7Ah battery running that 75watt pump because the battery is just too small.