Going Green - RC Groups
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Jul 31, 2012, 07:10 AM
It can't rain all the time
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Going Green

Hi Folks
The latest projects
After experimenting with the solar panel for caravanning I have installed a panel on the roof of the Bungalow .
Ok its only a small panel but it will give me more than enough free electricity for my own use ( lighting and charging the RC batteries )
The Caravan system uses a 120w solar panel 120Ah battery and a 500 watt inverter enough for the 5 day trips we usually do . Happily running the TV, lights and other small items .
The Home system is a little smaller using 100watt solar panel 160Ah battery and 2 x 300watt inverters This is ample ,since I upgraded to a bigger battery and a second inverter to power the television and HiFi Systems .
The downside of the inverter system is the overhead, with a 300w system about 8 watts and over 18 watts with the bigger inverters this must be taken into account when designing and commissioning the system . A 100% 12 volt only system would be more efficient in the long run as the losses would be minimised .
As you can see at home we already have a wood burner and a solar water heating system and both cut the cost of heating the water and the home .
The Solar water heating is effective for ten months a year and the wood burner will heat the bungalow to 24 deg C with outside temperatures of 0 deg C . the running costs of the wood burner are much less than running the central heating and gives a more homely feel . One advantage of the wood burner is the ash ( which there is only a little), it adds minerals to the garden and is effective to grit the paths in winter and protects the strawberrys from slugs in the summer,
another is that it recycles all the old pallets and timber into heat during the winter months.
Updates photos
On a finer note the 300 watt inverter has an overhead of less than 8 watts the 500 watt at 18 watt is higher ( more than twice and less than twice the output ) therefore it is better in my system to use 2 x 300 inverters rather than a single big one and of course I can always switch one off when not in use, saving a bit more energy.
update 30/9/12 160 Ah battery capacity 2 inverters and c/o switches
latest photos added 7,8 and 9
Last edited by twinkle; Nov 06, 2012 at 06:52 AM. Reason: 3rd update and spelling
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Aug 03, 2012, 01:04 PM
It can't rain all the time
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The Maths and the overheads

Hi Folks

I must point out here this is a working systems but does have its limitations

Here in the UK we work to 4 hrs of sunlight a day in march and september
so with a 100 watt panel 4 hrs and 85% efficiency the maths are

100 x 4 x .85 = 320 watt /hours

if the inverter was left on ALL THE TIME you would waste 8w x 24hrs =120 wh /day

so switching it off when not in use makes sense with a small system

the WH of the 80ah batteries ( 2 x 40 in parallel ) 80x12 =960 wh AT 20 hr discharge rate is 48 watt /hours ( 4 amps ) at 200 watt hours this will fall to about 4 or 5 hours a day if the inverters are switched off when not in use
this is still ok for me as the batteries are charging through the next day

This system still is adequate for my use during the evening when the electricity is being used and after all it is free eventually the batteries will be increased to 300 Ah and two small ( 300 watt ) inverters used as the overheads of the smaller inverters are less than the bigger one .

As I said before Its free and will take about 2 years to recoup the bits I purchased . And it doubles as emergency lighting if I run the system from the grid .

regards all emma
Aug 06, 2012, 05:57 AM
It can't rain all the time
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designing your own

Hi Folks

Try this website for more info on designing your own solar system


hope it helps

includes a simulator and other interesting features
and gives a lot of information on home and RV system designing
but dwells little on the overheads of the system

Last edited by twinkle; Aug 06, 2012 at 05:59 AM. Reason: laptop cant spell
Aug 28, 2012, 04:00 AM
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More mods

The Battery capacity has been increased to 120 Ah and the second inverter has arrived from China . Another 300 watt one as the overheads are lower . Still working . and enough capacity to use every day with a reserve . The real test will be in the winter months to see just how efficient the panel really is when the sun is low in the sky and there is less daylight per day to use ..

Its wait and see time- - - - - - - - - - - - - - - - - - - - - - - - - - -
Sep 10, 2012, 07:01 PM
It can't rain all the time
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The Solar regulator has been replaced with a german made dual charge system and now with two banks of two 40amp gell batteries
Thats a total of 160 Ah so far being charged by a 100 w Solar panel

We have fitted an inverter on each bank, one bank for the Tv and skybox whilst the original bank provides the lighting .
No problems yet with running out of battery power

We have one spare socket for any auxiliary equipment that we want to run or charge eg laptop or mains lipo charger although that is a waste as it is more efficient to use a 12v charger to minimize losses and gain efficency

The cheapo Chinese inverter died soon after and has been replaced with a better model still 300 watt nominal 500 watt surge with a usb charge output and a fan which switches on when loaded this also reduces the overhead . the only disappointment is the inverter does not have any mounting brackets so I manufactured some.

We will continue to monitor and post
for more details please PM me or leave a comment
Last edited by twinkle; Oct 05, 2012 at 10:14 AM. Reason: more info , etc
Sep 27, 2012, 10:20 AM
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The almost finished project

well Folks
The inverters are in and secure the batteries all connected and all the wiring needs is a bit of tlc but we all up and working . Both the current Inverters have automatic fans which come on as the load increases and there is now a 12v point outside the cupboard to monitor the battery voltage and to use as a takeoff to charge the lipos .

The Charge led can be seen glowing on the charge controller on the alloy heatsink ( black surround )

60% of the lighting ( the most frequently used lights ) are powered by one inverter and the tv and sky box the other .
this means the main electrics ( low current ) are being powered by FREE electricity. Leaving only the bulky items , fridge , oven and washine machine on the grid .
Over the next 18 months the system should pay for itself assuming the unit rate does not go down , which is very unlikely

Me yes Im pleased and last week the caravan system was put through its paces again when we went to a site without electric . Not a problem all week .

at the weekend we put the system throgh its paces using the Tv during the day for an hour and the tv and lights used for 5 hours in the evening without a hitch
Last edited by twinkle; Sep 30, 2012 at 06:34 PM. Reason: 2nd update
Oct 07, 2012, 03:52 PM
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The nights are drawing in

Hi Folks

With the nights drawing in, comes another problem, the sun is lower in the sky and the panel output is definably lower , to the point where the batteries do not recharge fully in a day. in fact they do not fully recharge in two days .
The next few months will be the proving of the system but I can foresee some additional work needed to maintain the battery voltage and charge rate by a second panel . The voltage output of a standard 12v panel has dropped from 19v on a summers day down to 15.6v on an dull October day . But Mid-day we still had over 5 amps of charge from the solar panel .
We found another little problem , The fuse and fuse holder was getting hot so we have replaced the standard 1 1/4 fuse with a car style 20 amp blade fuse. Tests over the past few days show that this little problem has now gone.

Now with 2 months till the shortest day , I think this means for the next four months the system will be struggling to maintain a high state of charge .

From my original calculation above with only 4hrs a day daylight it takes over 3 days to recharge the batteries if they are only 50% discharged

It really does need a 2nd panel for the next few months to maintain the output I have achieved during the summer.

Just acquired a second-hand 40 watt solar panel , I hope this will boost the output enough to keep it running for the next few months

The maths 4hrs 140 watt 85 % input = 560 watthours X 85% efficiency = 475 watthours an increase of 35%

regards for now
Last edited by twinkle; Nov 01, 2012 at 01:55 PM. Reason: update rather than another blog entry
Oct 28, 2012, 06:32 PM
It can't rain all the time
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Hi Folks

The second solar panel is fitted and wired in with a few little changes made and some more tests carried out .
The hour went back today to GMT and we are getting about 10 hours of light a day
and 14 hours of darkness .
Today it was very overcast and trying to rain , No sign of any sun . We had 650 ma of charge from the panels:- quite a lot less than the 8amps we were getting summer.
Off load today we had 20 volts from the solar panels.
But not enough current to charge up the batteries , lets hope we might get some sunny days through the winter.

Further tidying up of the system including another free mains electric socket outside the cupboard and a quad blade fuse holder for future modification
Now I can see this is going to become a project of continuous improvement and modification.
update 30/10/12 Battery fully charged indicator illuminated today the second panel appears to be helping the situation
photos added

edit 19/11/12 the solar panels are still keeping the batteries up all is well as the nights are getting longer

will keep you updated
Last edited by twinkle; Nov 19, 2012 at 01:24 PM. Reason: 3rd update photos added 4th edit 19/11
Nov 05, 2012, 05:33 AM
It can't rain all the time
twinkle's Avatar

Weather Station

Hi Folks

The Extra current supplied by the second panel is keeping the batteries charged

Last weekend we put a Maplin weather station on the roof stayed away from the chimney on an offset pole , great little toy (40 delivered ) EXCEPT There is NO wind direction Indicator . I must make a weather cock vane or plane . Oh Well another project .
Here are the photos
Nov 05, 2012, 08:15 PM
FPV junkie
m_beeson's Avatar
nice project
Dec 04, 2012, 01:24 PM
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December update

Hi Folks

The extra 40 watt panel seems to have solved the charge problem
still ok as we approach the shortest day

The water temp is down to the high 30s as the sun ( if and when ) is now so low in the sky , roll on februay / march when it becomes usable again

We have a little opportunity with the weather station , if the wind is in the wrong direction the air around the sensor can give the wrong temperature when the log burner is alight , Only needs a little adjustment next time I feel the need to scurry up the ridge tiles
I will live with it until we have a fine warm day
Last edited by twinkle; Dec 04, 2012 at 01:28 PM. Reason: more info
Dec 09, 2012, 03:50 PM
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On the roof again

Hi Folks

Just a quick update, the windspeed sensor stopped working over the weekend It would spin and then lock up , free off and run again , I stripped it down after running up the ridge tiles and bringing the whole unit down , the sealed bearing appears to be lacking in lubrication so re oiled it with 3 in 1 and its ready to go back up . I will move the unit so its easier to maintain and away from the heat of the wood burner's chimney , whilst sitting next to the base unit we noticed the external temp sensor is reading a degree higher than the internal one. We will need to keep an eye on the system.
Last edited by twinkle; Jan 10, 2013 at 04:45 PM.
Jan 10, 2013, 04:51 PM
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update 2013

Hi Folks

The weather sensors went back up on the roof and are working again
the temperature sensor IS reading high , about 1 degree at 10 deg C

The solar panels are still keeping up with the demand of the lighting and
the electricity bill for the last quarter shows that I used less power than this time last year

A result you might say
will give another update when we have anything to report

Update 31st January 2013 rather than do another entry

The Solar panel is back to "normal" this week with the bright sunshine we have had the Batteries are full charged again

Update 17/2
The Solar hot water system is starting to produce Hot water again , Today the Tank was at 40 deg C
So it was about 10 weeks of 52 that the output was minimal
Also the batteries were fully recharge after 2 evenings of use ( 2 x 7 hours ) with the sun we had on Sunday

This weekend 22/2 - 24/2 /13 the lights were used for 5 hours a night for 3 days and the batteries coped with the load
and recovered enough between uses The extra 40watt panel was enough to help for the winter period
but the poor sunlight did not heat the water very much

regards emma
Last edited by twinkle; Feb 25, 2013 at 08:20 AM. Reason: update 17/2/13 and 25/2/13
Mar 15, 2013, 09:17 PM
springer's Avatar
Hi Emma: Just read through this thread and it's an exciting experiment! I've dabbled (mentally and in print) with solar for a while (since we moved out into the country 28yrs ago, I guess) but not really built anything. Your setup has me thinking again! Got any pix of the water heating setup? Also, how did you wire up the house? What gauge wire did you use, and is it wired to each room or just a couple sites?

I guess I have done at least one thing to use renewable energy, this fall we put in a heatmore outside stove that when it's all hooked up will heat our house, an unattached shop and a studio for the wife's (and hopefully daughter's and daughter-in-law's) craftwork. Where we are located, I can get as much standing dead timber for firewood as I want. (unfortunately due to the emerald ash borer, there's a ton of dead ash trees available in local woodlots).
Apr 09, 2013, 06:10 PM
It can't rain all the time
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Aprils update

Hi Folks

The Batteries have expired on the weather station sender unit already.
They were supposed to last a year , well they haven't , brand new Duracell batteries were installed in January when I put the unit back on the roof after the bearing on the wind speed sensor failed , so far I am not over impressed, I will have to bring it down again and convert it to a 3v psu supplied system .

The Electric generating Solar panels are working well and I am reaping the benefits of free TV and lighting and my electricity bill shows a decrease again this quarter so its starting to pay for itself even over the winter period .

As for the solar water heating the little sun we have had, has not heated the water much over 40 deg C unless it has been a very good day and they have been few and far between ..

Still any saving is a good saving .

regards emma

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