Hi,

I have been thinking about solar for a couple of years , but financially I do not hav ethe funds and secondly power consumption is low therefore return on investment will be long.

For our household of 3 we use 15-18 KW per day. 

I will therefore keep on looking for a Cheap solution but thought about to just set up solar lights outside as a Security precaution during loadshedding and to start to learn about solar a bit more.

 

I was thinking about 5 x 20 W 12 V lights.

 

For this I would only need solar Panel/s , a charge controller and Battery if I am correct.

If I work out what the battery for 12 hours it gives me 100AH , end therefore I need to purchase a 200AH battery. 

I would like to know if this is correct , as 200AH battery seem big if I only have a few lights on, although it is for 12 Hours. 

What Solar Panel would I require to charge the batter @ 6 hours a day.

 

Thanks Cheese.

 

If you are only interested in backup power during power outages then you don't even need PV panels. 

And yes,  a DC solution also makes for an efficient solution. Then you only need your LED lights (make sure they are low voltage) a battery and a mains charger... 

I would like to use these permanently , replacing the 'EsKom' Lights .

But a 200AH baattery seems to be quite big for 5 20W lights for 12 Hours

 

Or is this just how it is.

 

 

4 minutes ago, Cheese said:

I would like to use these permanently , replacing the 'EsKom' Lights .

But a 200AH baattery seems to be quite big for 5 20W lights for 12 Hours

 

Or is this just how it is.

 

 

Remember this is for a 12v system. 

200ah on a 48v battery will power 100w lights 4 times longer. 

I'm powering my whole house from 222ah 48v lithium batteries for over 6 hours. 200ah 12v battery will not even run my kettle. 

11 minutes ago, Cheese said:

I would like to use these permanently , replacing the 'EsKom' Lights .

But a 200AH baattery seems to be quite big for 5 20W lights for 12 Hours

 

Or is this just how it is.

 

 

That's correct if you're going to use something like a lead acid battery that can only be discharged to 50% to prevent damage.

14 hours ago, Achmat said:

Remember this is for a 12v system. 

200ah on a 48v battery will power 100w lights 4 times longer. 

I'm powering my whole house from 222ah 48v lithium batteries for over 6 hours. 200ah 12v battery will not even run my kettle. 

Ok, Thanks that makes a big difference.

 

 

14 hours ago, Achmat said:

Remember this is for a 12v system. 

200ah on a 48v battery will power 100w lights 4 times longer. 

I'm powering my whole house from 222ah 48v lithium batteries for over 6 hours. 200ah 12v battery will not even run my kettle. 

Ok, If I have a 48V I would only need 50AH for the 100Watts for 12 hours.

To get the 48V I can connect 4 12V batteries in series, I assume each one of the batteries need to be 50AH 

39 minutes ago, Cheese said:

Ok, If I have a 48V I would only need 50AH for the 100Watts for 12 hours.

To get the 48V I can connect 4 12V batteries in series, I assume each one of the batteries need to be 50AH 

Yes but you don't get 48v DC lights so you will then need an inverter and normal 220v AC LED lights. Comparing prices of different battery voltages can be tricky and normally comes out to the same price when working out kWh.

 

4 x 50Ah 12v batteries would be similar in price to one 200Ah 12v battery. Then you still need factor in cabling to get the 4 batteries to a bank of 50Ah at 48v.

1 x 40Ah 12v lithium will cost in the region of R6.5k taking 4 to R26k whereas 1 x 50Ah 48v lithium battery could be had for R20k

1 x 45Ah 12v AGM battery is about R1.8k and 4 will be R7.2k. 1 x 200Ah AGM is about R6.5k.

 

I would just stick to the 200Ah AGM battery if just for LED lights and keep them on DC.

1 hour ago, Achmat said:

Yes but you don't get 48v DC lights so you will then need an inverter and normal 220v AC LED lights. Comparing prices of different battery voltages can be tricky and normally comes out to the same price when working out kWh.

 

4 x 50Ah 12v batteries would be similar in price to one 200Ah 12v battery. Then you still need factor in cabling to get the 4 batteries to a bank of 50Ah at 48v.

1 x 40Ah 12v lithium will cost in the region of R6.5k taking 4 to R26k whereas 1 x 50Ah 48v lithium battery could be had for R20k

1 x 45Ah 12v AGM battery is about R1.8k and 4 will be R7.2k. 1 x 200Ah AGM is about R6.5k.

 

I would just stick to the 200Ah AGM battery if just for LED lights and keep them on DC.

48V is not required for a DC solution, only if you are going to use an inverter. And there's a hectic price for using an inverter due to the power required simply to keep it idling.

Also you don't need a 200Ah battery for LED lighting (unless you have a warehouse to light up!)

1 hour ago, Richard Mackay said:

 

Also you don't need a 200Ah battery for LED lighting (unless you have a warehouse to light up!)

So how much Ah do you need to power 100w of led lights for 12 hours using 12v AGM batteries. 

19 minutes ago, Achmat said:

So how much Ah do you need to power 100w of led lights for 12 hours using 12v AGM batteries. 

100W @ 12V is 8.3A

8.3A for 12h is 100Ah

53 minutes ago, Richard Mackay said:

100W @ 12V is 8.3A

8.3A for 12h is 100Ah

Double of you are running from AGM as you don't want to run them below 50% SOC. Which takes me to 200Ah.