MJLorton Solar Power and Electronic Measurement Equipment Forum
Youtube Video Episodes => YouTube Video Episodes => Topic started by: MJLorton on March 11, 2013, 09:26:47 AM
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Link to the video tutorial here: https://www.youtube.com/watch?v=_ZN9gOlkOtI
In this video I talk about sizing your solar power system and in particular taking losses into account:
Grid Tie or Off Grid...some more handy info on losses and batteries:
http://www.aprs.org/off-grid-maybe.html
Getting an idea of solar radiation / insolation in your area:
http://www.matthewb.id.au/media/world_insolation_map.gif
http://www.nrel.gov/gis/solar.html
Solar Power calculator:
http://www.matthewb.id.au/media/Solar_Power_Calculator.html
http://www.dako.co.za/solar_system_calculator.html
Need Solar power measurement kit? ;-)
http://www.tester.co.uk/catalogsearch/result/?q=solar+pv+kit&cmid=QmhzQjcxYjVlc1E9&afid=bFcwbzliNzVDc289&ats=Nkk5bU53Uk5sSEE9
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Love all your vids especially the solar stuff.
Something to note. If you trying to work out a 40% loss, you technically can't just add it. ie 8200+40%= 11480 but 11480-40%=6888
I know it's just averages so it might be close enough...
Wish I could tell you the exact way to calculate it but I myself don't know and can't seem to be able to look it up, maybe someone else knows?
Thanks again for the great work you do!
P.s maybe i am missing something
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Love all your vids especially the solar stuff.
Something to note. If you trying to work out a 40% loss, you technically can't just add it. ie 8200+40%= 11480 but 11480-40%=6888
I know it's just averages so it might be close enough...
Wish I could tell you the exact way to calculate it but I myself don't know and can't seem to be able to look it up, maybe someone else knows?
Thanks again for the great work you do!
P.s maybe i am missing something
Hello Chaser,
Thanks very much for the feedback...and a big thanks for picking up that maths fluff!
It should be (where x is the required watt hours) x-0.4x=8200 therefore x=8200/0.6 = 13666 watt hours!
Will annotate now.
Cheers,
Martin.
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Hi Martin,
I have been enjoying your videos and especially the recent ones on the Solar Power.
Just curious on one aspect ov your own setup.
You have a hybrid system ov both grid tie & off grid inverters. Do you run both from the same array? (From I got from watching is that you have a grid tie inverter and then for the batteries you have an inverter charger which I presume is then A.C. coupled into the GTI?)
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Hi Martin
Great work with the videos much impressed.
Regarding the losses involved math I understand the need to subtract your 40% losses from the 100% value you actually need demand wise ie x-0.4x=8200
I just can not work out how you get to x=8200/.6
I am sure its straight forward however it just will not click.
Hope you can help.
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Hello Chris,
Thanks for your post.
What I really need to do is re-work and post a spreadsheet I have to assist with sizing and calculating losses.
The complication is that the losses can only be properly calculated once you have the sizing correct...a little chicken and egg...
If I don't have it here in a week or so please post again and nag me...
Cheers,
Martin.
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Hi Martin
Yes it is a chicken egg story!
I have been putting a spreadsheet together and this is why, regarding the losses, needed an equation to formulate an answer and got stuck on the maths.
I have spent a few days brushing up on my algebra and worked out the math of the equation. It was actually very simple I had just forgotten some of the rules on combining like terms!
Thanks for getting back to me and I look forward to checking out your spreadsheet.
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Hi Folks...
Here at last is the solar power system sizing spreadsheet...it is still a work in progress as there is one more formula I need to get working (variable battery SOC level).
If there are any obvious errors or bits that should be added ...let me know.
Cheers,
Martin.
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An awesome tool!! Thanks so much Martin.
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Thanks, my pleasure...just remember it's still a work in progress...
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Great video on properly sizing your solar system.
Very informative and surprising.
Did not realize the amount of loss due to heat.
Maybe having an automatic water system to cool the panels could fix that problem , just an idea.
By the way, regarding:
>> I just can not work out how you get to x=8200/.6
You know 8200 is the kwh with a 40% loss, so 8200 is 60% of your 100%, so:
8200 kwh ------ 60%
X kwh ---------- 100%
8200 x 100 = X x 60
X = (8200 x 100) / 60
8200 times 100, divided by 60, equals X
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Hello Mariense,
Thanks for the feedback.
There are folks that now produce a hybrid "solar panel" that produces both electricity and heats water. They send cool / cold water through pipes behind a PV to make it more efficient and end up with warm / hot water as a by-product to go into a hot water cylinder.
There are a few versions now:
http://www.earthtechling.com/2012/04/hybrid-solar-panels-yield-electricity-hot-water/
http://inhabitat.com/new-solar-thermal-flat-panels-are-eight-times-more-efficient-than-existing-technology/
http://www.alternative-energy-action-now.com/hybrid-solar-panels.html
Thanks for the better explanation of the equation too.
Cheers,
Martin.
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To help those having trouble calculating required watt hours:
x = required watt hours (to achieve 8200wh after 40% losses)
x-x(0.4)=8200
x(1-0.4)=8200
x(0.6)=8200
x=8200/0.6=13.67 kwh
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Hi MJLortan,
I have this assignment on space applications of solar arrays and battery banks. I have been assigned to calculate the size of the battery bank which is needed based on 508,000Wh per day will you be able to direct me in the correct path, do you have any ideas which could help me thanks and love the youtube videos very clear information
Thanks
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Thanks for all the effort and really useful information on solar power.
I am currently busy with an off grid project, and would like to include a small 220v emergency petrol generator to the system.
My question is , would I need to use a grid tie inverter to hook up the generator or is there a cheaper way of doing this?
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There are three ways to connect a generator as a backup. The first is with a grid tie type inverter but this isn't always the best way nor the least expensive. One problem is if the AC waveform output quality of the generator isn't that good, which is usually the case, then you can have problems with the inverter qualifying the power as good and passing it on to the load.
The second is to use a generator and a separate battery charger. This way your generator can charge the batteries directly and not cause any switching interruption or power quality problems. You just need to start your generator and it supplements the batteries directly.
The third is to use the generator directly to the load by using a bypass switch which just disconnects the inverter from the load and connects the generator directly. This has only one advantage in that you have a true second source of power should the solar system fail in any way.
IMHO, with much experience, it is best to use a combination of the last two options. Charge the batteries directly with a separate charge and also have the option of going direct to the generator.