Configuring my solar system

[scheek]

Built 3 /65 watt SP back in 2009. They are still working. I did this to learn and test the waters.

I have since started construction of my off grid cabin. I have just purchased 6/100 watt SP. I will also buy the supporting batteries needed within the next few months. I have not purchased an inverter and really not sure as for just how much wattage I need and what kind. Main thing I will be supporting is lights, refrigerator (optional propane), ceiling fans, water pump. This is a 900 sf cabin, well insulated.

I would like to utilize the 3 /65 home made panels. I'm pretty sure I shouldn't hook all the panels in parallel but keep them on separate arrays and use different controllers to charge the same batteries (of course I read this). I'm thinking I will need around 1200 ah of batteries to perform my task. I will also have a backup generator. Again., not sure of just how much KW I will need. I have a friend who has done this and his generator will activate when the voltage goes too low (I need to research this more and find out what the controller is that does this). He has a nice generator (14KW) but I'm thinking I would like to get by with one much smaller with an electric start. I have been researching if the EU3000is Honda might do. This is a nice, small, but expensive generator. I like the size. My friend says his generator rarely turns on during the nicer part of the year. July and August in Mississippi is time to go home under a good AC and forget the cabin.

With all of this said, I would like some input on a what you may suggest for my remaining system. I'm trying to do this as economically as I can but I don't want to do anything twice. My batteries and array will be a within 40 feet of each other and the cabin is about 75 feet from them. So I must figure best way (wire size, etc) and where the main panel box should be located.

I will stop here and listen. I don't want this too long.

Thanks.

[inetdog]

With all of this said, I would like some input on a what you may suggest for my remaining system. I'm trying to do this as economically as I can but I don't want to do anything twice. My batteries and array will be a within 40 feet of each other and the cabin is about 75 feet from them. So I must figure best way (wire size, etc) and where the main panel box should be located.

I will stop here and listen. I don't want this too long.

Thanks.

Good. The first rather than the last thing you need to do is get a very accurate idea of the load you will need/want to support. Everything else starts from there.
Changing a system in midstream to a different load requirement is totally wasteful.

First load, then inverter and battery bank and then panels.

[classradiance]

system calculations if this helps you then great

Built 3 /65 watt SP back in 2009. They are still working. I did this to learn and test the waters.

I have since started construction of my off grid cabin. I have just purchased 6/100 watt SP. I will also buy the supporting batteries needed within the next few months. I have not purchased an inverter and really not sure as for just how much wattage I need and what kind. Main thing I will be supporting is lights, refrigerator (optional propane), ceiling fans, water pump. This is a 900 sf cabin, well insulated.

I would like to utilize the 3 /65 home made panels. I'm pretty sure I shouldn't hook all the panels in parallel but keep them on separate arrays and use different controllers to charge the same batteries (of course I read this). I'm thinking I will need around 1200 ah of batteries to perform my task. I will also have a backup generator. Again., not sure of just how much KW I will need. I have a friend who has done this and his generator will activate when the voltage goes too low (I need to research this more and find out what the controller is that does this). He has a nice generator (14KW) but I'm thinking I would like to get by with one much smaller with an electric start. I have been researching if the EU3000is Honda might do. This is a nice, small, but expensive generator. I like the size. My friend says his generator rarely turns on during the nicer part of the year. July and August in Mississippi is time to go home under a good AC and forget the cabin.

With all of this said, I would like some input on a what you may suggest for my remaining system. I'm trying to do this as economically as I can but I don't want to do anything twice. My batteries and array will be a within 40 feet of each other and the cabin is about 75 feet from them. So I must figure best way (wire size, etc) and where the main panel box should be located.

I will stop here and listen. I don't want this too long.

Thanks.

HOW TO CALCULATE YOUR MONEY SAVING SYSTEM for Home / Boat / Caravan / Shed
1.Add up the hours that each light will be on for to get the Total of Energy Consumed.
2.From that you can Calculate everything you need IE: Solar Panel / Battery / Regulator
------------------------------------------

My Calculations
3 Zones
1 X LED SPOT @ 10W + 2 x LED FLOOD @ 15W
on for (SEE CHART) hours per night
...................

-Watt/Hour Chart- - Only ever use 12 volt LED lights -

3 Room scenario

kitchen/Diner 15W on when required daily average use -- 3 hours = 45wh
Bedroom 10W on when required daily average use - 2 hours = 20wh
front Room 15W on when required daily average use - 8 hours = 120wh

Total usage per night in Winter = 185wh/d
-----------------------------------------------------------------------------------------

-Load and Battery -

House Lights Consumption = 185Wh
185 watt-hours divided by 12 volts = 15.42 amphours taken from system in 1 night

Because we can only use half the energy in a lead acid battery without harming the battery,
the minimum battery size is 15.42 amps x 2 = 30.84 amp hours.
the minimum battery size is 15.42 amps x 2 = 30.84 amp hours
or 15.42ah / .5(50%) = 30.84ah or 15.42ah / .3 (30%) = 51.4ah or 15.42ah / .2 (20%) = 77.1ah, choose what calculation will be best for your battery !!
10% discharge

I want my system to be reliable if we have four consecutive days of cloudy weather,
4 days of autonomy x 30.84 = 123.36 amp hours for the battery. = 124 + amp hour battery
(Required Battery Bank = 1 x 130 Ah True Deep Cycle


-------------------------------------------------------------------------------------------

-Charging Battery from Panel-
This installation is in a location that gets 5 hours of full sun per day.
Check the charts for this depending on the month in the Season.
To recharge the battery for one day of use we need 30.84 amps in 5 hours = 30.84 / 5 = 6.17 amps from a 12 volt solar panel array.
------------------------------------------------------------------------------------------------------------------------

-Solar Panel -
Most load calculations include a discount factor for the inefficiency of recharging the battery.
20% is typical. 6.17 / 0.8 = 7.71 amps.

A single 140W solar array that has an Impp (amps maximum power point) of 7.7A would be suitable

------------------------------------------------------------------------------------------

-Charge Controller Rating in AMPS-
The 140W solar array has a short circuit amp rating (Isc) of 8.2A 8.2A x 1.25 = 10.25A
use a 10.3A or larger charge controller with this array to charge the battery.

Cheap example - 20A Unit
For best efficiency to charge use an MPPT Type.
------------------------------------------------------------------------------------------

- estimated Cost of mentioned Materials - 20 years / $450. = $500./240 months = £2.08 month = .52 per week ....wow

Have seen 140w poly panel on Net for $170 inc delivery
Have seen 130Ah Varta Leisure Battery 12V 130Ah for around $150 inc delivery
20A Charge controller $20 - $60 - mppt prefered of course
3 QUALITY External (For in or out & VERY BRIGHT) LED Lights 2 x 15w/1 x 10w = $60
100m of .75mm twin and earth from wholesalers = $30
Mounting Bracket for Panel = $20

Estimated Total = $500ish

Also required - Fuse box / switches / bits ..


-----------------------------------------------------------------------------------------
-Solar Panel specification-
STK-140P6-A ...... manufactured by 3E
Related power
140W
Open circuit voltage Voc(V)
23V
Short-circuit current Isc(A)
8.2A
Optimum operation voltage Vmp(V)
18.3V
Optimum operation current Imp(A)
7.7A
.......................

[PNjunction]

:HOW TO CALCULATE YOUR MONEY SAVING SYSTEM

Uh oh. You will NOT be saving money. Especially when one delves into homebrew windmills and diy solar panels for "free electricity". I've seen the videos. Maybe as a costly learning experience.

[PNjunction]

With all of this said, I would like some input on a what you may suggest for my remaining system. I'm trying to do this as economically as I can but I don't want to do anything twice.

Then you definitely want to get a handle on your loads first. Grab a P3 Kill-A-Watt meter, a decent multimeter, and start documenting. RS has them on the racks typically. Everything else depends on that if you don't want to do it twice. Or more.

[classradiance]

Nothing is free .. If it only takes up your own time . .that was a cost !!

Uh oh. You will NOT be saving money. Especially when one delves into homebrew windmills and diy solar panels for "free electricity". I've seen the videos. Maybe as a costly learning experience.

Hi PNjunction

I used to study Transistor theory which really is what you can call a nightmare.
Interesting that the Transistor Study is the same as this Solar Topic !! You are calculating Power consumption within a Component at the design phase.
In contrast the calculations for Solar Lighting have been placed here in a Simple template format that may help you.

You are right in a way where the learning curve comes at a price, but when the knowledge gained is passed on for free to others
..... Satisfaction !

Costs of Panels are now getting very cheap as Mass production drives down the cost.
Batteries can be picked up !! or you can invest.
Magnets for Stator plates can be found in Microwave ovens . . etc . .etc

What is it you need help with?
Its always a pleasure to try and solve problems.

[PNjunction]

What is it you need help with? Its always a pleasure to try and solve problems.

I think scheek is the one looking for a solution, not me.

I'll pass on the cheap stuff. I don't want to pay for things twice - once for the cheap crap to fail, and then yet again for what should have been purchased in the first place.

[classradiance]

Read all about it -

I was once told that in the science of Electronics you can get away with things .. sometimes !!
So the message is build and see, where parameters can be left out of the recipe if certain conditions are met first !!
The condition of having an over sized Battery Bank for instance, or more collecting Panels.
Cable at low voltage should be respected, and never shortcut the risk of fire.
LED lights are of such low power in the 12V world, they are a designers dream.
You really can light your house / boat / caravan / shed / garden / with a small amount of Electrical/Electronics knowledge.
The maths above are really as hard as it needs to get.
Get a simulator or learn the calculations of OHM's Law - Both really.
The old saying is eat it / sleep it / for a while and you wont look back.
Always get your system calculations checked for safe use and away you go.