Absolutely new to this

[WahineX]

HI. I've watched Will's videos and bought his book but I am still afraid of doing the wrong thing and hurting my equipment. As long as I get the right components, I think I will be fine.

I want to run:
(2) 100w pond pumps, 24/7
(2) 300w pond pumps, 24/7
(1) 35w air pump, 24/7, and
(2) strings of 125W patio lights, 1 hr per days max.

I already purchased:
(2) 200 Watt 12 volt mono crystalline (HQST)
(4) 100 Watt 12 volt mono cystalline (HQST)
I live near SF, so I get 6 hours sun in winter and 12 hours in summer. I could use the grid in winter, or run some pumps less.
It will be outdoors (in a box).

From my calculations I will need a minimum of (17) 12v batteries. This has to be wrong. What else would I need?

It would be nice if the system was upgradeable in the future. Maybe add in a turbine to the system.

Thank you in advance for the help.

 

[FilterGuy]

From my calculations I will need a minimum of (17) 12v batteries. This has to be wrong.

It may not be that far off. You describe some very large loads. Lets do some math.
(I will assume the pumps and lights are all DC.)

• (2) 100w pond pumps, 24/7 = 2 x 100W x 24hr = 4800Whr/day
• (2) 300w pond pumps, 24/7 = 2 x 300W x 24hr = 14400Wh/day
• (1) 35w air pump, 24/7, = 35W x 24 = 840Wh/day
• (2) strings of 125W patio lights, 1 hr per days max. = 125W x 1 = 125Wh/day

Total Whr/day = 4300Wh/day + 14400Wh/day + 840Wh/day + 125Wh/day = 20165wh/day

I will assume LiFePO4 batteries and an average voltage of 3.22V/cell (12.88V).

That means you need 20165Wh/12.88V = 1566 Ah to run the system for one day.

The wattages you gave sound like the name-plate numbers so the calculations are a little high. Lets be overly optimistic and say the actual need will be 80% of the numbers calculated.

.8 x 1566Ah = 1253 Ah. If you have 100Ah Batteries, that comes out to 12.5 or 13 batteries. If you want to be able to operate through two consecutive cloudy days, it comes to 25 100Ah LiFePO4 batteries or 50 Lead acid batteries.

I already purchased:
(2) 200 Watt 12 volt mono crystalline (HQST)
(4) 100 Watt 12 volt mono cystalline (HQST)
I live near SF, so I get 6 hours sun in winter and 12 hours in summer. I could use the grid in winter, or run some pumps less.
It will be outdoors (in a box).

let's calculate what that will produce.

The sun intensity varies through the day so we use what is known as an Insolation number for calculating daily output. (This number represents the number of full-intensity-equivalent hours) For the SF area 5 or 5.5 is a reasonable summertime number.

• Your 200 Watt panels will generate 2 x 200 x 5.5 = 2,200Wh/day if they operate at full rated capacity.
• Your 100 watt panels will generate 4 x 100 x 5.5 = 2,200Wh/day if they operate at full rated capacity.
• The total capacity of the 6 panels is 4400Wh/day if they operate at full rated capacity.

In real life, panels produce something closer to 80%-85% of their rated capacity. Consequently, a reasonable expectation is that the 6 panels will produce 4400Wh/Day x .8 = 3520Wh/day.

The loads will need about 5 times more power than the panels will create each day.

 

[chrisski]

I already purchased:
(2) 200 Watt 12 volt mono crystalline (HQST)
(4) 100 Watt 12 volt mono cystalline (HQST)
I live near SF, so I get 6 hours sun in winter and 12 hours in summer. I could use the grid in winter, or run some pumps less.
It will be outdoors (in a box).

I recomend no more purchases until you finalize your requirement. Otherwise you’ll end up with a Frankenstein Syst‘em.

In my signature block there is a Solar Calculator. You won’t get 6 X panel rating in the winter nor will you get 12 X panel rating in the Summer.

I did this to @Filter Guy’s Requirement. If you have a 20161 per day wh requirement, if you installed 7 kw of panels, about 9 times what you have now, and built a battery bank with 21000 watt hours, which is 18 batteries 12 volts at 100 ah, you’d have a full battery at some point in the day 3/4 of the time, and 1/4 of the time or more, you’d have used 80% of the batteries capacity.

The weather and sun angle really effects that power production.


I’ve found this ”Solar Calculator” to be accurate for my location in Arizona. The link is in my signature block.