Question about 100w solar panel for small devices

What did you mean before the first comma? Thanks

 

So, if I decide to put something together to begin to replace my grid use waste, suppose I determine what I'll need to run my fridge let's start with, which is I think 6amp x 110 volts = 660w x 8hrs I read the average fridge runs a day, = 5.3kwh right? Then by the month x 30 =158kwh x elec. Co. charge of 8 cents =about $13 a month savings would that be right? I'm just trying to first get an economical overview of what I can achieve here. It's that basically it? And then there's of course calculating your equipment requirements which seems pretty straight forward that I read but that's another question. Thanks

 

Keep in mind, and it's been said before in this thread but bears repeating, that label numbers are a good place to start a SWAG but only just that. You need to purchase a Kill-a-watt meter and get accurate numbers specific to your situation.

You plug it in between the wall an you device and it tells you exactly what the device is drawing...exactly, not a guesstimate and unless you are overbuilding your system because you literally have money to burn, exact numbers are what you need.

That MUST be your starting point or you will be constantly short and or drawing your batteries down too far and destroy them.

The exact numbers are needed to ensure that you account for the surge/startup draw for any inductive motor (fridge compressor) but also lets you determine and account for any phantom loads you have (soft power buttons as opposed to manual power switches).

You are getting the basics, but from this point on it's just a guess without real, hard, factual numbers. You could be off by 20%+ in one direction or another which makes a huge difference in the end numbers.

 

Golf carts are TWO flavours in Voltages , 36Vdc (6 x6Vdc=36) or THE MEANER 36 HOLE TYPE 48Vdc (6 x8vdc =48Vdc )
~~~~~~~~~~~~~~~~~~~~~~
Mine is 48Vdc with a trace 2500W inverter on its back , 3 140W panels & a Kid with WBjr & a tri shunt system . I can weld off the cart !!
Stay away fro 36 volt units , not a nice pair into housing inverters !!

Not dickering , but waiting for the go ahead !!
I need to pull flat-decks & fork lifts to make this easy on the old men (me)

Any free battery to destroy & play with , it's the Batterys that die will cost YOU !!!

Math is close (closer than many )
As said Kill-a-watt (Harbour freight has them ) 20.00 to let you know loads & It will enlighten you !! As it did me .
TV was a hog off !!! wall warts are a parasitic draw .

If you play , buy stuff that can let you play @ 12 , 24 , ---48Vdc as in a charge controller ,as for fridge , thats a 1500W inverter to start the compressor in full wave or not a POS Modified square wave that will kill the motor !! So maybe try a grid tie feedback inverter & then your not out of pocket when you change & move up in voltage .
I run 12 , 24 , 48 Vdc systems 7 differnt systems all over . None are alike but the back wood cabins in the mountains (SURVIVAL IF A STORM GETS YA) .
Sloth

 

If your fridge is using 5kwh per day the most economical thing to do is get a new fridge.

 

He is just using math , & no Kill-a-watt , more like 1,5-1.9 kw/24hrs . Frost free are the worst hogs . Do a manual defrost & have better food . Less extracted from the food it's keeping !

 

Also @juntjoo
New inverter in your power style is coming out as the Little Willy from Midnite also !!
It's in the final testing of CSA +

Sloth

 

The first thing you need to buy is 1 or 2 kill-a-watt meters, the P3 edition. Those will track actual useage.
Also don't go off watts, go by VoltAmps. Inverters and generators only care about VoltAmps.

 

Thanks. Lots to digest. So before I get a killawatt what are we looking at around? 2.5kw inverter? Do I just have to figure what my max watt output per time possible(all surge startup devices at once surging) + average energy draw to cover that and no more? What does it mean to "draw your battery down" having calculated too high on your energy requirements? Let me guess b4 googling: battery needs to regularly drain to keep healthy?? And what's wrong with 36v batteries? I think I almost got it lol. Why are we welding? Apocalyptic preparation? Ability to rebuild stuff when no welder or pre-built solution available? Did mad max have welding abilities, or was he just a tough guy with a lot of friends and bullets?

 

I like the modular'ness of the grid tie inverter. Anything else that needs to be specifically sought after like a charge controller or just plan for the max? And what needs to be uniform, batteries, panels? I like flexibility with minimal components

 

From your first question, you're doing it backwards. The whole point of the kill-a-watt is to answer the question "What are we looking at here". Without knowing what your actual utilization is, anything is a total guess which could be high (waste of money as you'll build/buy too much) or low (insufficient and will kill your batteries among other things). Step one, get real numbers with a kill-a-watt.

Which leads to your other question about battery draw down, and what you said you assumed it meant. No, no, no, no, no. That is the literal and exact opposite of what should happen. NEVER draw (use) more than 75% of the usable, not rated, capacity of a deep cycle battery before recharging. Draw down means pulling from or using and drawing it down over that will kill the usable capacity. The older the battery, the lower % too, more like 50%.

The usable capacity is whatever "full" means and that changes with age. Full at brand new is the max the battery will ever be able to hold and is referred to as rated capacity. The old saw "your mileage may vary" is apt here since with age, the capacity decreases for a number of reasons. Never use more than 75% of usable capacity before recharging unless you already have replacements on hand (yes, perhaps a bit overstated but you get the point).

 

You can't go by name plate watts.
1 they name plate watts, you need to know voltamps.
2 the name plate ratinga are usually higher than actual and you don't know how much the device is on, such as a refrigerator, it turns on as needed.
If you had the yellow energy use tag for the appliances when you bought it then you would have a pretty good idea how much it uses, but most people ignore or throw them away.

 

That IS not a recommended way of keeping the the 12Vdc system up , If the 12Vdc has loads or a bad cell the 24Vdc system will feel a parasitic draw & makes the diagnosing very hard,

Better is to make the Classic MTTP unit switch the 12 Charging on when the 24Vdc system is in (Float ,or at amps , Or % of charge or many other factors you can pick)
That way the systems are joined but not dependent on the 24vdc .

Sloth

 

If I got a free 36v forklift battery on would sell it and buy a 24 or 48v bank.

 

Whoa! You're hardcore. Or it's just all new and amazing to me. But thanks for that run-down of your setup. Easy to understand and interesting.

So you got a 36v you split up, 2x6v & 4x6v, and sun going straight to the 4x6v which then charges the 2x6v and the 12v part is for all DC devices while the 24v w/ inverter is AC stuff.

And then you said you have some sort of additional gas charger too. I guess that's common practice to have more than one source of power on your system. In a typical setup do you have the 12v vehicle battery system hooked up to feed the main energy system as a backup? If typical, or with whatever backup you have connected, is it usually setup with simply a switch to include or exclude in 'the loop'? Would it be like an input switch on the back of the charge controller?

Good stuff