A 50w panel can generate 50w of power in 1hr. So if you expose the panel in whole day, it can generate 50Wx 5hr=250whr of power. But this is just a theory calculation. Not yet minus some bad thing.

You need to know your device usage. Than you can know the panel can support or not. Let say your device suck 20w and you want to use 10hr. That is 20wx10hr=200whr. So it is under 250whr panel. Your device are good to go.

For battery is a bit complicated.

For on-grid, you need get a approving installer. Can't DIY. Just only the document, can kill you.

Your fan is only require 9.6w. If you run for 1hr,  it only consume 9.6wx1hr=9.6whr. Your panel supply more than enough power. The problem is the voltage. 18v is too high for the fan. Any possibility burn down the fan.

You need a charge controller to regulate the voltage down to 12v. The charge controller also  can use for charge the battery.

Read back previous post.

Too much poison is it?

50w panel what you want maximize? Can generate 100w from 50w?

You can do a calculation.

50w expose 5hr a day, 50wx5hr=250whr. 1mth output is 250whrx365day/12=7.6kwh/mth.

Given the TNB rate is 0.218sen/kwh. So 7.6kwh x 0.218sen = RM1.65/mth can be reduce.

Is it possible?

Don't ever think to invest solar power to reduce TNB bill, unless you apply Feed In Tariff. Our electricity is still consider low compare to those developed countries.  When the day TNB charge RM1 per KWH, then you can think to invest solar power.

You need a 45AH battery. You don't drain your battery to zero. It will shorten the battery life. So put it at 50% or more of battery usage. This calculation is also just provide 1day backup. If you have cloudy day next day, you won't be able to run full of your fan.

The remaining 19hr is using 183whr. 183whr/12v = 15.25AH.

12.25AH / 0.5 = 30.5AH of battery. Than you need to consider the rate of discharge. Cincai put it at 0.8.

So you need 30.5AH /0.8 =38AH battery.

What you have run in your home 24/7 ?

You mean want to power this dispenser is it?

But you got to check the power consumption first. Get a kill a watt meter to check for a mth. Get the average consumption usage. Than only can do the calculation.

0.218 is just a basic calculation. More accurate is depend on your average usage yearly.

Example my average is RM59.09 peryrs. Average is 0.24/kwh.

But you cannot use my example. Cause your usage is probably lower or higher than me. You have to comeout your rate.

The more appliances you have the more  expensive you will be paying.

If you are paying at 0.218, that mean you are using less than 200 units per month. I am impress how you can achieve this. Can you describe to me what appliances you have, and how long it run a day?

The last I did help my friend calculate, his meter was tempered and he reported it back to TNB. Lucky enough he did not have to pay anything because he just got the house 2nd hand, and TNB when chase after the original owner 

under the SEDA's FIT system, all the electricity is sold to TNB. above RM1/kwh.  Don't use it if you got FIT quota. Sell all to TNB. more worthwhile.

you can try to install an off-grid system (generate for your own use) but generally not worth it.  Msia electricity cheap.

check out;

1. http://seda.gov.my/

2. https://forum.lowyat.net/topic/2661898

all in there..... please read....

Yes, installed solar fit system.

I don't understand. You said you use solar at night. So what solar that give out electricity at night? Is it somekind of new technology?

buy electricity from TNB (per unit) -> 22sen / kwh
sell electricity to TNB (per unit - via FIT) -> more than RM1.00 / kwh

for home use (incl air-con) buy from TNB lah.

solar generation, all sell to TNB also. baru ada untung !