how many solar pannel to connect for 875VA inverter

[suneel117]

I'm using 875VA home inverter with 150aH battery.
how many watts of solar panel can be connected using charge controller.

i want to use charge battery and use for home appliances (TV,fans etc) at the same time using solar source.
Isn't possible?

Thanks

 

[Centmo]

Is this for an off-grid installation?

The rule of thumb is to connect a total power rating of PV modules equal to 110% - 120% of the inverter rating, but it depends on where you live. This is because PV modules spend very little time (or in some cases, no time) at their rated power, and to match their total power rating to that of the inverter would be a waste of inverter capacity. During the very short periods of time in a year when modules do pump out rated power, the inverter just dials them back slightly by adjusting the load to put them off their maximum power point (MPP).

 

[suneel117]

I want connect in this way.
at day time i want to charge battery using solar
at night time use DC-AC inverted current

How many panels are required and ?Amps of charge controller are needed?


thank u

 

[Centmo]

If you are interested in learning all about the design of a PV system such as the one you're describing, I recommend this book:

https://www.amazon.com/Photovoltaic-Systems-Engineering-Third-Edition/dp/1439802920

You do not have to be an engineer to understand it, as the math is very basic. He gives step by step instructions on how to design a PV system, from determining how big your system should be based on your loads, to selecting an inverter/charge controller, batteries, PV modules, wiring, to laying them out on your roof. Covers the entire process.

If you want a rough idea of how big your charge controller and PV array should be based on re-charging a 150Ah battery, tell me what location you are in.

 

[suneel117]

Vijayawada, Andhra Pradesh, INDIA

 

[Centmo]

If we assume your battery (12V, 120Ah) is depleted down to 20% after a night of use, then you need to put 12*120*0.8 = 1152Wh back into it during the day to recharge it. If we assume a 90% charge efficiency, this is 1152/0.9 = 1280Wh to be supplied by the PV system during the day just to recharge the battery. Assuming an inverter efficiency of 95%, this is 1280/0.95 = 1347Wh = 1.35kWh from the PV modules. If we assume that the PV module is polycrystalline, and 13% efficient, then you would need 1.35/0.13 = 10.38kWh of solar radiation on the PV modules.

https://eosweb.larc.nasa.gov/cgi-bi...p=1&lat=16.519028&lon=80.621494&submit=Submit

For Vijayawada, the worst case month is July, with an average of 4.17kWh/m^2/day horizontal radiation. So, if you laid your PV modules flat, you'd need 10.38/4.17 = 2.49m^2 of PV module area. If you tilt the modules at the correct angle, you might get an extra ~10-15% solar radiation. So, 2.49/1.1 = 2.26m^2. But, there are other losses in the system (such as dust on the modules, wiring losses, MPPT losses, PV module mismatch, etc..) which may add up to ~5%. 2.26/0.95 = 2.38m^2 of PV modules.

A typical PV module (~13% efficient) might be rated for 170W, and 1m x 1.3m = 1.3 m^2. So, you might need two of these, so 340W total.

Keep in mind, that this is JUST to re-charge the battery on an average July day. If you are also using electricity during the day while the battery is charging, then you might want to double the size of the PV array, to 680W.


Edit: I just realized its a 150Ah battery (not 120Ah), so multiply everything by 150/120 = 1.25. 680W * 1.25 = 850W. Also, if you want to be able to charge on a cloudy day you might want an even bigger system. So, your 875VA inverter sounds suitable for the application. If you tell me the model of the inverter, I can help you choose the number and type of PV modules to get.