14 October 2012, 19:23

I love the idea of not paying for Electricity, and being an Electronics Engineer thought I would build my own system.

The whole Solar thing is made out to be complicated but its easy !!

Many Cars now have these Low Power Led's as Headlights/Back Lights etc

You can Leave them on all night in a car and it would not have even touched the Battery.

Found as strips or units they are usually 1W or 3W but in groups are very bright - So Bright that they blow away anything that is a normal standard 12V Car Bulb.

Being so Bright even in Daylight and using such a small amount of Power from the Battery over x amount of hours, Solar Lighting Systems can now

be made from a few pieces of Hardware, for not allot of cash.

- But calculations are critical -

Remember that what Power you take out - must be returned to the Battery.

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How to calculate a Complete Single Light System for a Cabin

1. Add up the hours that the 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

1 Zone

1 x LED FLOOD @ 15W (could be 5 single 3W LED units)

on for (SEE CHART) hours per night

...................

-Watt/Hour Winter Chart- - Only ever use 12 volt LED light -

1 Zone - 15W on when required daily average use -- 4pm until 10pm - 6 hours x 15 Watts = 90wh

Total usage per night in Winter = 90wh/d

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-Load and Battery -

Cabin Lights Consumption = 90Wh

90 watt-hours divided by 12 volts = 7.5 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 7.5 amps x 2 = 15 amp hours.

I want my system to be reliable if we have four consecutive days of cloudy weather,

4 days of autonomy x 15 Amps = 60 amp hours for the battery. = 60 + amp hour battery

(Required Battery Bank = 1 x 60 Ah minimum - True Deep Cycle

cost so far = 15 for LED light + 50 Battery = 65 quid

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

-Charging Battery from Panel-

This installation is in a location that gets 4 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 15 amps in 5 hours = 15 / 5 = 3 Amps every hour 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. 3 A / 0.8 = 3.75 Amps.

A single 70W solar array that has an Impp (amps maximum power point) of 3.9A would be suitable

Based on (Model - CS6D - 70P / Manufacturer - Canadian Solar Inc.)

cost of PV Array = 80 quid

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

-Charge Controller Rating in AMPS-

The 70W solar array has a short circuit amp rating (Isc) of 4.21A 4.21A x 1.25 = 5.3A

use a 5.3A or larger charge controller with this array to charge the battery.

Cheap example - 10A Unit

For best efficiency to charge use an MPPT Type = 30 quid

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

-Solar Panel specification-

CS6D - 70P..... manufactured by Canadian Solar

Related power

70W

Open circuit voltage Voc(V)

22.1V

Short-circuit current Isc(A)

4.21A

Optimum operation voltage Vmp(V)

17.8V

Optimum operation current Imp(A)

3.93A

etc ... Caution -12V Batteries can Cause Fire if not Fused or Stored Correctly-

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

That's it - and if you like, just double up on the panels and Battery to create a system with double the lights.

Just remember that 12V systems are limited to Cable distance.

So 1 x 15W Flood would have a .75mm Diameter no longer than 6 meters.

Just spider it all out to get around that or double up on the cable diameter to double the distance.

Store the Battery in a dry/ventilated place where no hands can touch Terminals.

Be aware of Fire Hazards as Car Batteries can be bad boys if ignored !!

If you get no Sun then drag out the jump leads and charge your system off a motor for a few hours ...

The whole Solar thing is made out to be complicated but its easy !!

Many Cars now have these Low Power Led's as Headlights/Back Lights etc

You can Leave them on all night in a car and it would not have even touched the Battery.

Found as strips or units they are usually 1W or 3W but in groups are very bright - So Bright that they blow away anything that is a normal standard 12V Car Bulb.

Being so Bright even in Daylight and using such a small amount of Power from the Battery over x amount of hours, Solar Lighting Systems can now

be made from a few pieces of Hardware, for not allot of cash.

- But calculations are critical -

Remember that what Power you take out - must be returned to the Battery.

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

----------

----

--

How to calculate a Complete Single Light System for a Cabin

1. Add up the hours that the 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

1 Zone

1 x LED FLOOD @ 15W (could be 5 single 3W LED units)

on for (SEE CHART) hours per night

...................

-Watt/Hour Winter Chart- - Only ever use 12 volt LED light -

1 Zone - 15W on when required daily average use -- 4pm until 10pm - 6 hours x 15 Watts = 90wh

Total usage per night in Winter = 90wh/d

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

-Load and Battery -

Cabin Lights Consumption = 90Wh

90 watt-hours divided by 12 volts = 7.5 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 7.5 amps x 2 = 15 amp hours.

I want my system to be reliable if we have four consecutive days of cloudy weather,

4 days of autonomy x 15 Amps = 60 amp hours for the battery. = 60 + amp hour battery

(Required Battery Bank = 1 x 60 Ah minimum - True Deep Cycle

cost so far = 15 for LED light + 50 Battery = 65 quid

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

-Charging Battery from Panel-

This installation is in a location that gets 4 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 15 amps in 5 hours = 15 / 5 = 3 Amps every hour 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. 3 A / 0.8 = 3.75 Amps.

A single 70W solar array that has an Impp (amps maximum power point) of 3.9A would be suitable

Based on (Model - CS6D - 70P / Manufacturer - Canadian Solar Inc.)

cost of PV Array = 80 quid

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

-Charge Controller Rating in AMPS-

The 70W solar array has a short circuit amp rating (Isc) of 4.21A 4.21A x 1.25 = 5.3A

use a 5.3A or larger charge controller with this array to charge the battery.

Cheap example - 10A Unit

For best efficiency to charge use an MPPT Type = 30 quid

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

-Solar Panel specification-

CS6D - 70P..... manufactured by Canadian Solar

Related power

70W

Open circuit voltage Voc(V)

22.1V

Short-circuit current Isc(A)

4.21A

Optimum operation voltage Vmp(V)

17.8V

Optimum operation current Imp(A)

3.93A

etc ... Caution -12V Batteries can Cause Fire if not Fused or Stored Correctly-

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

That's it - and if you like, just double up on the panels and Battery to create a system with double the lights.

Just remember that 12V systems are limited to Cable distance.

So 1 x 15W Flood would have a .75mm Diameter no longer than 6 meters.

Just spider it all out to get around that or double up on the cable diameter to double the distance.

Store the Battery in a dry/ventilated place where no hands can touch Terminals.

Be aware of Fire Hazards as Car Batteries can be bad boys if ignored !!

If you get no Sun then drag out the jump leads and charge your system off a motor for a few hours ...