Calculations for Solar Lighting System - 20 years / $2k = $8.3 per month

[classradiance]

HOW TO CALCULATE YOUR MONEY SAVING SYSTEM
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
14 Zones
15 X LED SPOT @ 10W + 1 x LED FLOOD @ 15W
on for (SEE CHART) hours per night
...................
-Watt/Hour Chart- - Only ever use 12 volt LED lights -
Down Stairs
kitchen    15W on when required daily average use -- 3 hours = 45wh
bed1           10W on when required daily average use -- 7 hours = 70wh
bed2     10W on when required daily average use -  7 hours = 70wh
hall           20W on when required daily average use -  2 hours = 40wh
toilet          10W on when required daily average use -  4 hours = 40wh
bed3           10W on when required daily average use -  1 hours = 10wh
utility         10W on when required daily average use -  2 hours = 20wh
front Room      20W on when required daily average use -  8 hours = 160wh
outside front  10W on when required daily average use -  1 hour = 10wh
outside back  10W on when required daily average use -  1 hour = 10wh

Up Stairs
stairs top      10W hardly used  daily average use -  2 hours = 20wh
toilet          10W on when required daily average use -  void as 2 exist
bed4     10W on when required  daily average use -  8 hours = 80wh
bed5           10W on when required daily average use -  4 hours = 40wh

Total usage per night in Winter = 615wh/d
-----------------------------------------------------------------------------------------
-Load and Battery -
House Lights Consumption = 615Wh
615 watt-hours divided by 12 volts = 51.25 amp hours.  Because we can only use half the energy in a lead acid battery without harming the battery, the minimum battery size is 51.25 amps x 2 = 102.5 amp hours.
(only do this if using a Lead acid Battery)
I want my system to be reliable if we have four consecutive days of cloudy weather,
 4 days of autonomy x 102.5 = 410 amp hours for the battery.  = 410 + amp hour battery
(Required Battery Bank =  2 x 220Ah or 4 x 110Ah or 8 x 55Ah
Autonomy allows for No charge over 4 days flat
------------
-Charging Battery from Panel-
This installation is in a location that gets 5 hours of full sun (insolation) 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 102.5 amps in 5 hours = 102.5 / 5 = 20.5 amps from a 12 volt solar panel array.
-----------------------------------------------------------------------------------------------
-Solar Panel Array-
Most load calculations include a discount factor for the inefficiency of recharging the battery. 20 percent is typical.  20.5 / 0.8 = 25.7 amps.
A  (5 panel) 500W solar array that has an Impp (amps maximum power point) of  25.7A would be suitable
The Panels SUM ( Impp ) must be more than the 25.7A ( 5 x 5.79A = 28.95A)
-----------------------------------------------------------------------------------------------------------
-Charge Controller Rating in AMPS-
The 500W solar array has a short circuit amp rating (Isc) of 5 X 6.46A = 32.3A.  32.3A x 1.25 = 40.375A
use a 41A amp or larger charge controller with this array to charge the battery.
Cheap example - 50A CM5024Z JUTA PWM Charge Controller
For best efficiency available for charging the batteries use a MPPT charge controller for lead acid.
-------------------------------------------------------------------------------------------------------------
-Cost of mentioned Materials - 20 years / 2k =  £8 month
100w watt poly solar panel = £80 + £15 delivery x 5 = £475 UK delivery
50A CM5024Z JUTA PWM Charge Controller = £85
Yuasa 12v 220Ah Cargo Batt For trucks £ 234.47x 2= £ 468.94 + shipping
1 x 15W Flood = £ 20, 15 x 10W Spot = £ 180 -- Total = £ 200
Twin & Earth 1mm x 100m = £ 29.58 from Electrical wholesaler
Max Length for 15w@12V = 6m of .75/Max Length for 10w@12V = 9m of .75
Total Cost can be either + or - dependent on your Budget . £2k / 20years = £8 per month
---------------------------------------------------------------------------------------
-Solar Panel specification-
Related power
100W
Open circuit voltage Voc(V)
21.5V
Short-circuit current Isc(A)
6.460A
Optimum operation voltage Vmp(V)
17.3V
Optimum operation current Imp(A)
5.79A
.......................

Thanks to everyone who places information out there on the WEB
Hope the above can inspire you.
Not mentioned above are Switches, Inverters, Distribution, Heating, Health & Safety,
etc ... Caution -12V Batteries can Cause Fire if not Fused or Stored Correctly- 

[Bruce S]

OKAY I've removed your previous post and still I need to ask!
... IS this your setup or are you posting specs to assist possible future users?
Not really sure where you're going with this 
Bruce

[classradiance]

The calculations required to Design a system are free to all whom require the knowledge from this post.
I hope it can help other enthusiasts to be interested in the topic, where design of such systems can get very complex and confusing.

 

[classradiance]

<...... Smaller calculations for just 3 rooms  ....>

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.

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

Thanks to everyone who places information out there on the WEB
Hope the above can inspire you.
Not mentioned above are Switches, Inverters, Distribution, Heating, Health & Safety,
etc ... Caution -12V Batteries can Cause Fire if not Fused or Stored Correctly-

 - Battery info -

Deep cycle batteries are designed to be discharged down as much as 80% time after time,
and have much thicker plates. The major difference between a true deep cycle battery
and others is that the plates are SOLID Lead plates - not sponge. This gives less surface
area, thus less "instant" power like starting batteries need. Although these can be cycled
down to 20% charge, the best lifespan vs cost method is to keep the average cycle at about
50% discharge.

Battery life is directly related to how deep the battery is cycled each time.
If a battery is discharged to 50% every day, it will last about twice as long
as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times
as long as one cycled to 50%. Obviously, there are some practical limitations on this
- you don't usually want to have a 5 ton pile of batteries sitting there just to reduce
the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean
you cannot go to 80% once in a while. It's just that when designing a system when you have
some idea of the loads, you should figure on an average DOD of around 50% for the best storage
vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less
will usually not last as long as one cycled down 10%. This happens because at very shallow cycles,
the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film.

Always get a another opinion on the above
IE: maybe a 30% discharge rule would be best for your system . . etc

[classradiance]

  I need feedback ...  Please post with your spec if this has helped ...

[Bruce S]

Most of us reading these are not sure if these are mere calculations OR something you've actually built in your home.
Pictures of finished setups with how well the lighting looks with light levels would be nice.
IF these are merely calculations of an install.
I would say better than 70% of the people here can do these themselves.

Come back with installs you're doing and pictures then we can give a better feed back.
Bruce S

[DamonHD]

Seconded: if you want feedback we need more specifics and narrower questions.  Your current question seems to be at the vagueness of "How can we fix the world's problems?"

Rgds

Damon

[classradiance]

FYI  if any body needs to see my equipment as an image/video. Please click your mouse on the play button at the bottom of the first post above.

If you would like to discuss Maths .. etc then please message me as 30% of the otherpower.com community may need help on the subject, I have been advised of this by Bruce.

  Please send me your feedback if any of this helps you ...

[DamonHD]

This is a forum to *discuss* things, so please keep discussion on here as much as you can; taking it off-board doesn't help other current or future members/visitors.

If you want to show off your skills, that's fine.  If you want to ask for feedback, please be specific.

Rgds

Damon

[bart]

   Thanks for posting.
You cleared up How I was calculating the inefficiency of recharging the battery.
Was just adding 20% of the total solar watts to make up for it and that was totally wrong.

   By the way, this or something like it would be nice in the FAQ for all us "newbies".

[classradiance]

 :)Thanks Damon and Bruce
Electronics is a complex subject, and Battery charging is mind blowing.
I discovered a few good links on utube /google/yahoo/net, about Batteries.

But it seems that cost is considered to be the best way to achieve quality !!
What say you? 

[Bruce S]

One small part about the youtube link; there are people here who cannot get to the youtube link as it may be blocked by firewalls at their workplace ( Mine included).
Hence my asking for pictures.

[Bruce S]

   Thanks for posting.
You cleared up How I was calculating the inefficiency of recharging the battery.
Was just adding 20% of the total solar watts to make up for it and that was totally wrong.

   By the way, this or something like it would be nice in the FAQ for all us "newbies".

Bart;
I'm pretty sure there's a very nice write up in the FAQ section for LEDs and the electronics done by two very knowledgeable people. One a complete overview which is so well done it should be taught in College or at least University done by Commanda and a build project done by Rich Hagen.
IF the FAQ is not there do a search for their names and look at their posts on this subject.
I'll wander over to the FAQ and see if they got misplaced.
Cheers;
Bruce S

[bart]

   Thanks Bruce, but....
I'm looking at this from the perspective of the basic set up of a solar system.
Figuring from Load (if LED,fine), to battery size, to solar panel size, etc...
And his write up also includes watt hours, to amp hours used, to battery size in amp hours, etc.
   For a newbie to try to grasp from watts to watt hours from what classradiance posted is a great help.
Although this info exist else where on the web, this is done in a concise and brief format.
 I have read what Commanda and Rich Hagan have done, just as a curiosity, because they are so far beyond
my skills at anything electronic, that maybe by reading their post it might ooze in.
Not really holding much hope there.

[Bruce S]

Bart;
 It is a very good read and having everything in one place can be very helpful.
Enjoy
Bruce S

[classradiance]

One small part about the youtube link; there are people here who cannot get to the youtube link as it may be blocked by firewalls at their workplace ( Mine included).
Hence my asking for pictures.

Hi Bruce

As a 3rd Line Support analyst, I too have had that issue.
Where in Secure environments like some of the Government buildings I have worked in over the years the Tears of Security which I cannot talk of here, are incredibly locked down as you can imagine.
My advice to you as a friend is not to try to breach the Wall which is there to keep yours and your company data safe.

If you feel the requirement to ask for images of my system, then it would be a pleasure to email them to you as a .RAR.
If that attachment is blocked then it may be possible for you to have the Email unblocked via you Administrator.
If that fails then please access my Link on a machine that is stand alone and off of your Network.

As it stands  .. today was clear and my battery charged up to it's full potential. That has made me feel very satisfied.

[Bruce S]

As a front line IT tech and Administrator , it is easy for me to take a break and look things up on either my cell phone or tablet.
However others may not have that ability, also there are still people who come here through dial up and satellite.
They are the ones I truly speak on behalf of.
 Thanks for the offer.

[Frank S]

Not to hijack this thread but there are those who pay by the KB for their internet service in some countries.

[dave ames]

I need feedback ...  Please post with your spec if this has helped ...

Still not sure what exactly you are up to with these postings?

If your motives are to be helpful and nothing else, then well done! Some people could use an example like this..and just plug their numbers in where yours are.

Some minor points to consider:

-many locations do not receive a full solar window (9am-5pm) need to derate for that..seems obvious but maybe not to some.

-should maybe do the 20% additional derate twice..Once for the solar modules and once for the batteries.

-corrected short circuit currents for solar arrays are usually ISC X 1.56

Kind regards,
Dave  <-who still wonders what this is leading to 

[ghurd]

Still not sure what exactly you are up to with these postings?

If your motives are to be helpful and nothing else, then well done! Some people could use an example like this..and just plug their numbers in where yours are

Kind regards,
Dave  <-who still wonders what this is leading to 

I would say better than 70% of the people here can do these themselves.

To me it looks like reinventing the wheel or the solar sizing worksheet.

A few areas appear overly complicated, while a few others are overly simplified (mainly about replacing used AH).

"today was clear and my battery charged up to it's full potential".
Full potential, as in regulation voltage?
Or fully charged?
There is a big difference between the 2.  (probably not a big deal because of some of the other numbers in your example)

The shown example would NOT work for me.  Average insolation here is a fairly typical ~4.5 hours, when I do not need much lighting.  Worst case is <0.5 hours, which is when I need more lighting.
Winter here makes London look like Hawaii.
G-

[classradiance]

Still not sure what exactly you are up to with these postings?

If your motives are to be helpful and nothing else, then well done! Some people could use an example like this..and just plug their numbers in where yours are

Kind regards,
Dave  <-who still wonders what this is leading to 

I would say better than 70% of the people here can do these themselves.

To me it looks like reinventing the wheel or the solar sizing worksheet.

A few areas appear overly complicated, while a few others are overly simplified (mainly about replacing used AH).

"today was clear and my battery charged up to it's full potential".
Full potential, as in regulation voltage?
Or fully charged?
There is a big difference between the 2.  (probably not a big deal because of some of the other numbers in your example)

The shown example would NOT work for me.  Average insolation here is a fairly typical ~4.5 hours, when I do not need much lighting.  Worst case is <0.5 hours, which is when I need more lighting.
Winter here makes London look like Hawaii.
G-

Thanks Dave

Very helpful for me .. I don't know it all which is why I am asking for feedback
Seems the whole point of this post has actually generated much interest.
What do you mean where is it going?
Its going where I wanted it, in the direction of helping others that may have struggled like me in the earlier days of putting the
hardware  together, but safely !!

You can expand or contract the above calculations, but like another so rightly said it would not be for him possibly.
Do this for me ? - > place the positive thoughts on here for everyone to see . . that's what this post is about.
Please remember to show me a spec and I will update my calculations with yours for a better way to design for lights.

So far I have learned this week about 20% / 30% / 50% points of view !!
The voices of solar forums are indicating an unhappy reflection regarding certain investments.
Claims of not getting the money back etc......... after rented space above roof does not return the promised calculation !!
(personally I see it as a way of living and not about money making which is why we are at this point on here
 - politics/economics -) hmmm
 


< - Massive thanks - >

[classradiance]

I need feedback ...  Please post with your spec if this has helped ...

Still not sure what exactly you are up to with these postings?

If your motives are to be helpful and nothing else, then well done! Some people could use an example like this..and just plug their numbers in where yours are.

Some minor points to consider:

-many locations do not receive a full solar window (9am-5pm) need to derate for that..seems obvious but maybe not to some.

-should maybe do the 20% additional derate twice..Once for the solar modules and once for the batteries.

-corrected short circuit currents for solar arrays are usually ISC X 1.56

Kind regards,
Dave  <-who still wonders what this is leading to 

.........................................>
30% Discharge rule
the minimum battery size is ( amps / .3 = amp hours )
20% Discharge rule
the minimum battery size is ( amps / .2 = amp hours )

You are right, but I left it off to simplify ... amazingly i never realized that a 10% calculation was not good until last week ..!!
Cheers for the ISC X 1.56, this is my point with all this !! you only find out when you put it all up for scrutiny.

[classradiance]

Still not sure what exactly you are up to with these postings?

If your motives are to be helpful and nothing else, then well done! Some people could use an example like this..and just plug their numbers in where yours are

Kind regards,
Dave  <-who still wonders what this is leading to 

I would say better than 70% of the people here can do these themselves.

To me it looks like reinventing the wheel or the solar sizing worksheet.

A few areas appear overly complicated, while a few others are overly simplified (mainly about replacing used AH).

"today was clear and my battery charged up to it's full potential".
Full potential, as in regulation voltage?
Or fully charged?
There is a big difference between the 2.  (probably not a big deal because of some of the other numbers in your example)

The shown example would NOT work for me.  Average insolation here is a fairly typical ~4.5 hours, when I do not need much lighting.  Worst case is <0.5 hours, which is when I need more lighting.
Winter here makes London look like Hawaii.
G-

Thanks for that
So what is your situation, do you have a generator and can you be more specific to see exactly what you mean.
30 minutes of irradiation can add up, if you have a vast amount of panels, none of us do !! so the model could be ?
What have you determined as best after years of trial and how much have you saved?
Its the point ... 

"Worst case is <0.5 hours, which is when I need more lighting" I would think you mean an alternative charging source ?

 

[classradiance]

 

Question .. over recent years has the Low Voltage Appliances market changed at all?
Is a new 24V fridge better now than say 5 years ago.

[ghurd]

So what is your situation, do you have a generator and can you be more specific to see exactly what you mean.
30 minutes of irradiation can add up, if you have a vast amount of panels, none of us do !! so the model could be ?
What have you determined as best after years of trial and how much have you saved?
Its the point ... 

"Worst case is <0.5 hours, which is when I need more lighting" I would think you mean an alternative charging source ?

 

No grid there.

"and how much have you saved?"
Saved on what?
No grid possible, so nothing saved on the electric bill.
Compared to gas powered gennies, many $1000s on fuel, maintainence, replacments, noise, etc (silly to run any gennie for a 15W soldering iron and 3W LED bulb).

"What have you determined as best after years of trial?"
Learn to adapt.
Like if there happens to be 2 good days of sun in a row and the bank reaches regulation voltage (different than 'fully charged'), then there is some power that can be used without effect on the actual battery state of charge, so thats a good time to get the cordless tool batteries charged up, etc.

Basically, the batteries are abused very badly during the winter, but that is when the money is flowing in from using the batteries.
If they get too low, the electric soldering irons are replaced by a butane iron, the LED and CFL lights are replaced by gas lamp (IE: Hippo types).
If it gets critical to have battery power for something, there is a 20A charger, but running a tiny 2-cyl gennie to get 8A (from a 20A charger) into a 800AH battery is silly.  If I am there at the right time, jumper cables from my truck to the house bank gave them a pretty good boost.

Added move PV this year, so we'll see how much that helps.
Have all the parts for a reasonably efficient gasoline powered charger (still) waiting to be assembled.
Had a small wind turbine in use for a while, needs some work on the bearings now, and not sure it helped much anyway (every little bit helps).

I should point out that is at the solder shop, and a friend's home.
I have grid at my house.
G-

[classradiance]

So what is your situation, do you have a generator and can you be more specific to see exactly what you mean.
30 minutes of irradiation can add up, if you have a vast amount of panels, none of us do !! so the model could be ?
What have you determined as best after years of trial and how much have you saved?
Its the point ... 

"Worst case is <0.5 hours, which is when I need more lighting" I would think you mean an alternative charging source ?

 

No grid there.

"and how much have you saved?"
Saved on what?
No grid possible, so nothing saved on the electric bill.
Compared to gas powered gennies, many $1000s on fuel, maintainence, replacments, noise, etc (silly to run any gennie for a 15W soldering iron and 3W LED bulb).

"What have you determined as best after years of trial?"
Learn to adapt.
Like if there happens to be 2 good days of sun in a row and the bank reaches regulation voltage (different than 'fully charged'), then there is some power that can be used without effect on the actual battery state of charge, so thats a good time to get the cordless tool batteries charged up, etc.

Basically, the batteries are abused very badly during the winter, but that is when the money is flowing in from using the batteries.
If they get too low, the electric soldering irons are replaced by a butane iron, the LED and CFL lights are replaced by gas lamp (IE: Hippo types).
If it gets critical to have battery power for something, there is a 20A charger, but running a tiny 2-cyl gennie to get 8A (from a 20A charger) into a 800AH battery is silly.  If I am there at the right time, jumper cables from my truck to the house bank gave them a pretty good boost.

Added move PV this year, so we'll see how much that helps.
Have all the parts for a reasonably efficient gasoline powered charger (still) waiting to be assembled.
Had a small wind turbine in use for a while, needs some work on the bearings now, and not sure it helped much anyway (every little bit helps).

I should point out that is at the solder shop, and a friend's home.
I have grid at my house.
G-

Thanks Ghurd

I enjoyed the read, and would say that "Learn to adapt" is something we are all having to realize more and more.
So at a push you would charge the Battery Bank with a vehicle!
Food for thought when planning where you are going to put the Bank maybe !!

 

[bob golding]

interesting if a trifle over complicated. i am off grid and  slowl;y built up my system as finance and time permitted. this will be the situation for most people. not many will get the calculator out and try and work the whole thing out in one go.

batteries are the biggest expense if this is for an off grid system. once you have brought the  biggest bank you can afford you can then start adding things as time permits. being UK based you no doubt have seen some of the schemes people have dreamed up on "grand designs" very few of them deliver what they should on paper.

i think most on here will have worked out most of what you have written already. when i started to work out the power requirments of my lighting CFL where the norm. then LED bulbs came along and now i am using led tape lights. so  doing long term projections over 20 years might not be the way forward as lighting technology might well be different in 20 years as batteries may well be too.

[classradiance]

Thanks Bob

6 of your major points:-

1.interesting if a trifle over complicated.
2.not many will get the calculator out and try and work the whole thing out in one go.
3.once you have brought the  biggest bank you can afford you can then start adding things as time permits.
4.i think most on here will have worked out most of what you have written already.
5.then LED bulbs came along and now i am using led tape lights.
6.so  doing long term projections over 20 years might not be the way forward as lighting technology might well be different in 20 years as batteries may well be too.
----------------
------------
--------
--
Please can you post an uncomplicated way to design a system for Lighting (1)

are you saying to design and build your first system where you  found you would firstly acquire the biggest bank of Batteries you could (2)

Not many will get the calculator out and work it all out when trying to begin the design of a system (3)
But most would have worked out a system based upon what I have already placed at the top (4)

LEDs came along and now are obsolete to Tape LEDs (5)

Don't bother to try and create a model of cost over time (6)
-------------------------------------------------
----------------------------
--------------
------

Thanks Bob, I shall try to consider your advise, and would like to know if your system when first built was running safely.
Was it that you built it first without calculations and tested with meters or did you just put it together after certain considerations.

What would you advise so that I can avoid possible Hazards or Risk, and have you any pictures please.

I am happy you discovered the strips, they really do the job, I have been told.
Did you use them because of the Light efficiency or because they are cheaper to run?
 

[bob golding]

will get back to you on the other things, but as regards the tape LEDs. someone gave me some at a meeting i organised for bio diesel producers. i had not come across them before. just shows you have to keep up!!

[classradiance]

WHY NOT  !!?   - New Scenario -

Each room LED has it's own smaller Battery and Charge Controller dedicated to it. say 1 x 10W LED & 1 x FewAmps Controller
Only one Sufficient PV charge source is in place.

Would this be better or worse for any reason than having 1 Large Battery and a Controller supplying all LED lights?

[ghurd]

It would be worse.

First, it would cost a LOT more.

Second, it woud be less efficient.  Peukert's Law.  And other things too.
G-

[classradiance]

 

I was told today that the yearly return on an 800W array Grid Tied, is 600 pounds.
Is this the same in the USA ?

What is going on?

[DamonHD]

An 800Wp array in middle England would generate ~600kWh/year which even if you used all the power displacing retail import would bag you maybe one third of what you are suggesting at best.

Rgds

Damon


Edit: fixed typo in units