Hi everyone.

I am from South Africa and enjoy an awesome 6 hours of sunlight hours (On Average). I got interested in solar about a year or 2 ago and have been hooked ever since.I have built my own 60W panel and a solar box that houses a 100AH deep cycle and the switches,fuses,meters etc.

I had bought that Earth for energy guide which helps only up to a point.The video says work on watts to size the system yet the additional pdf with the formula equates everything to Amps.So I had a bit of a confusing time.I then came across this site and browsed articles to get some info on how to size a pv system in Watts using different formulae.(Thank you Sunking,Russ,Mike etc)

After doing the browsing on this forum,I have pieced together how to work out formula for "Battery Sizing" and "PV Sizing" to charge the batterys in the correct time frame.This is JUST what I have gathered and need it to be verified by one of the forum members who know their stuff like the people mentioned above so not to mislead anyone else.

Temperature Correction Factor Table for below calculations:

80 F / 26.7 C = 1.00

70 F / 21.2 C = 1.04

60 F / 15.6 C = 1.11

50 F / 10.0 C = 1.19

40 F / 4.4 C = 1.30

30 F / -1.1 C = 1.40

20 F / -6.7 C = 1.59

I am using 1 day autonomy

1. 1000 WH (Needed for 1 day)

2. 1 day autonomy (Just an example)

3. 1000 wh x 1 = 1000 wh (Replace "1" with days autonomy for your own calculations)

4. 50 % = .5 (Depth of discharge,remember the less discharge the longer the batteries last but the more cost)

5. 1000 wh / .5 = 2000 wh

6. 1.11

7. 2000 wh x 1.11 = 2220 wh

8. 2220 wh / 12 volts =

1. How long it will take to charge the above 185 AH battery with the panels you have right now with 50% DOD.

2. What PV Watts are needed to charge the battery ideally in 1 day

1. 50% battery is 93 AH @ 14V (charge volts) = 1302 WH to replace

Say you have a 120W PV Panel already.

120W panel x 80% = 96W (Actual panel size taking inefficiencies from the panel into account,including charge controller inefficiency?)

1302 WH / 96W = 13.6 hours to fully charge.

13.6 hours / 6 Sun hours = 2.26 days to fully charge. ( 6 hours of sun in South Africa)

2. 1302 WH to replace / 6 hours sunlight = 220 W panel (Rounde off)

220 W panel / .80 = 275W Panel needed to recharge the 50% DOD in 6 hours (1 Day) taking panel inefficiencies into account.

So anyways.These are the formula taken from various parts of the site.Please verify if they are correct or show me where I can tweak (Without getting ridiculously detailed,this is a guideline.)

Thanks!

I am from South Africa and enjoy an awesome 6 hours of sunlight hours (On Average). I got interested in solar about a year or 2 ago and have been hooked ever since.I have built my own 60W panel and a solar box that houses a 100AH deep cycle and the switches,fuses,meters etc.

I had bought that Earth for energy guide which helps only up to a point.The video says work on watts to size the system yet the additional pdf with the formula equates everything to Amps.So I had a bit of a confusing time.I then came across this site and browsed articles to get some info on how to size a pv system in Watts using different formulae.(Thank you Sunking,Russ,Mike etc)

After doing the browsing on this forum,I have pieced together how to work out formula for "Battery Sizing" and "PV Sizing" to charge the batterys in the correct time frame.This is JUST what I have gathered and need it to be verified by one of the forum members who know their stuff like the people mentioned above so not to mislead anyone else.

Temperature Correction Factor Table for below calculations:

80 F / 26.7 C = 1.00

70 F / 21.2 C = 1.04

60 F / 15.6 C = 1.11

50 F / 10.0 C = 1.19

40 F / 4.4 C = 1.30

30 F / -1.1 C = 1.40

20 F / -6.7 C = 1.59

**Battery Sizing**(From Sunking - http://www.solarpaneltalk.com/showth...ing-Calculator)I am using 1 day autonomy

1. 1000 WH (Needed for 1 day)

2. 1 day autonomy (Just an example)

3. 1000 wh x 1 = 1000 wh (Replace "1" with days autonomy for your own calculations)

4. 50 % = .5 (Depth of discharge,remember the less discharge the longer the batteries last but the more cost)

5. 1000 wh / .5 = 2000 wh

6. 1.11

7. 2000 wh x 1.11 = 2220 wh

8. 2220 wh / 12 volts =

**185 Amp Hours**@ 12 volts. (Rounding off may come into play here)**PV Sizing**2 formula can be used:1. How long it will take to charge the above 185 AH battery with the panels you have right now with 50% DOD.

2. What PV Watts are needed to charge the battery ideally in 1 day

1. 50% battery is 93 AH @ 14V (charge volts) = 1302 WH to replace

Say you have a 120W PV Panel already.

120W panel x 80% = 96W (Actual panel size taking inefficiencies from the panel into account,including charge controller inefficiency?)

1302 WH / 96W = 13.6 hours to fully charge.

13.6 hours / 6 Sun hours = 2.26 days to fully charge. ( 6 hours of sun in South Africa)

2. 1302 WH to replace / 6 hours sunlight = 220 W panel (Rounde off)

220 W panel / .80 = 275W Panel needed to recharge the 50% DOD in 6 hours (1 Day) taking panel inefficiencies into account.

So anyways.These are the formula taken from various parts of the site.Please verify if they are correct or show me where I can tweak (Without getting ridiculously detailed,this is a guideline.)

Thanks!

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