Solar Panels - Information and Questions
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what was your end resolve ?madtuna said:
Ward69 said:
Give this link a go Ward69,
https://computer.howstuffworks.com/question28.htm
Cheers
Doug
Ward69, (most) dont 'switch over'.. The output runs on the internal battery & inverter, & the mains power keeps it charged.
Im setting up solar panels for a room AC and trying not to use batteries, so Im looking for the opposite to a UPS switch technology, want start the AC with mains power and then switch over to the panels when theres power and vis-verser switch back to mains when theres no power coming out of solar panels. Thinking the UPS technologies is the solution. Just idea. No-one has come up with it. I think
Ward69 said:
Best to dig a bit further in your research and supplies terminology so we don't get off on the wrong track, as all the UPS's that I have worked on have usually had a battery. But having said that domestic solar systems that interface to the mains, use smart technology to synchronise the solar inverter output to the mains, but they do NOT supply your house if the mains goes off unless you have a battery supply as part of the system. Main reason I guess is what happens if the mains fails when there is not enough sun light!
It is quite a few years since I was "in the game" so things may be available now that I am not aware of, so others may have some better ideas.
Rob P.
Thanks Rob and DD. I think Ive work it out. Law of physics
If you have a ray of 4 solar panels(250watts)full sun light, it puts out 1000watts. = 239vls
If the AC is 4.18 amps and uses 930watts, the mains is 220vlts(Manila) so the extra 19volts is pushed back in to the grid. Only when the panels comes under the 220vlts it uses the mains power
If the panels only pushing say half (cloudy day) 500watts = 120Volts The mains kicks in and adds the extra 100volts
Am, I on wrong track.
Thanks Mark
If you have a ray of 4 solar panels(250watts)full sun light, it puts out 1000watts. = 239vls
If the AC is 4.18 amps and uses 930watts, the mains is 220vlts(Manila) so the extra 19volts is pushed back in to the grid. Only when the panels comes under the 220vlts it uses the mains power
If the panels only pushing say half (cloudy day) 500watts = 120Volts The mains kicks in and adds the extra 100volts
Am, I on wrong track.
Thanks Mark
Sort of, but not exactly, you are mixing up power (watts) and Volts.
The solar panels, however many you have (12 in my case) connect to an inverter that will generate an output voltage to match the grid voltage and exact frequency (nominally 50Hz). NB: This matching the mains volts/freq, is very important/critical, else bang/boom. This feed that you supply goes through the power company meter to measure how many watts of power you are putting into the mains. If the Inverter can't generate any power it drops offline.
Your building power is fed from the mains power line via another meter and into your premises. The power company then works out the value of your power provided by you at your agreed rate. It is stated on you power bill along with the power that you use at your input rate, and the difference is what you pay.
So you aren't really using your power with this basic solar system in Oz.
Does this make sense?
Rob P
The solar panels, however many you have (12 in my case) connect to an inverter that will generate an output voltage to match the grid voltage and exact frequency (nominally 50Hz). NB: This matching the mains volts/freq, is very important/critical, else bang/boom. This feed that you supply goes through the power company meter to measure how many watts of power you are putting into the mains. If the Inverter can't generate any power it drops offline.
Your building power is fed from the mains power line via another meter and into your premises. The power company then works out the value of your power provided by you at your agreed rate. It is stated on you power bill along with the power that you use at your input rate, and the difference is what you pay.
So you aren't really using your power with this basic solar system in Oz.
Does this make sense?
Rob P
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hi guys and gals.
Is trying to get my head around what size solar panel I would need to charge a 12v 7ah VRLA battery. It basically going to be use only on a led camp light set up at night and possible to run a blue bowl in the field if the need arises.
I know I not going to have to go a big panel and reg. Would I be safe to go a 20watt panel with a Current at Power at 1.15 amp with a 12V 3A PWM Solar Charge Controller if not any ideas on a set up.
Cheers
Is trying to get my head around what size solar panel I would need to charge a 12v 7ah VRLA battery. It basically going to be use only on a led camp light set up at night and possible to run a blue bowl in the field if the need arises.
I know I not going to have to go a big panel and reg. Would I be safe to go a 20watt panel with a Current at Power at 1.15 amp with a 12V 3A PWM Solar Charge Controller if not any ideas on a set up.
Cheers
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A quick search on Google got this.
https://solartown.com/learning/sola...erters-for-your-off-grid-solar-energy-system/
It might help you understand the calculations a little better. Also remember solar panels are rated for optimum conditions, throw in some cloud or extreme temperatures and those figures quickly get thrown out the door.
Get the best quality charge controller you can afford, cheap ones do not do well overall. If you are looking at carrying things around, a lighter battery system like Lithium Ion might suit your needs; more power, compact and less weight (18650 batteries). ALWAYS build a system for MORE than you think you will need, otherwise you might get left in the dark! :lol:
https://solartown.com/learning/sola...erters-for-your-off-grid-solar-energy-system/
It might help you understand the calculations a little better. Also remember solar panels are rated for optimum conditions, throw in some cloud or extreme temperatures and those figures quickly get thrown out the door.
Get the best quality charge controller you can afford, cheap ones do not do well overall. If you are looking at carrying things around, a lighter battery system like Lithium Ion might suit your needs; more power, compact and less weight (18650 batteries). ALWAYS build a system for MORE than you think you will need, otherwise you might get left in the dark! :lol:
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Even with all the research WtN i'm still trying my head around it, the simpler the question the more difficult the answer.
A-TEAM is on the ball.
Personally i thought i had it covered with putting a house solar panel on the roof of my car. It has plenty of watts but not the amps required for 12v apparently you have to halve the amps of said capacity.
example; My solar panel says max amp. 9.4 @24v.
Halve that for 12v. and that's the optimum you get on a good day which works out to be 4 amps (rouphly) input as long as the sun is in your favour.
Mine and every bodies fridge usually draws 3.5 amps to 4.5 amps an hour.
So the next question is your battery?
How long can it run at night before going flat/unusable?
A 100ah battery will usually last 2-4 days from fully charged.
A-TEAM is on the ball.
Personally i thought i had it covered with putting a house solar panel on the roof of my car. It has plenty of watts but not the amps required for 12v apparently you have to halve the amps of said capacity.
example; My solar panel says max amp. 9.4 @24v.
Halve that for 12v. and that's the optimum you get on a good day which works out to be 4 amps (rouphly) input as long as the sun is in your favour.
Mine and every bodies fridge usually draws 3.5 amps to 4.5 amps an hour.
So the next question is your battery?
How long can it run at night before going flat/unusable?
A 100ah battery will usually last 2-4 days from fully charged.
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A-team said:
Yeah has a 130 ah lithium on main set up with a 30 amp mppt reg and 250 watt panels. But on the 7ah battery that set up would it be to powerfully for the battery and fry it really quick lol hence looking at trying to get a small feed system with next to no amp coming down the line so to speak..
Gem in I said:
I have the hot water -a heat pump system-installed thru a time switch so that it only uses solar power from 0830-1630. Big money saver. The heat pump can hold the hot water,hot, for 3-4 days.
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where the nugget said:
Just be aware that VRLA batteries require a specific type of charger:
http://www.power-plusbattery.com/CATALOGS/Technical Documents/VRLA Batteries ChargingMethods.pdf
You'll need to make sure that any solar controller you buy can handle this type of battery.
I use something like this for charging small VRLA's at home:
https://www.jaycar.com.au/12v-1a-sla-battery-charger/p/MB3619
but that's not much use to you in the field, unless you have an inverter to drive it - I keep one of these in the glove box for those little 240V jobs:
https://www.ebay.com.au/itm/Portabl...m3fe68bb80c:g:250AAOSwYXdfK7Ge&frcectupt=true
The inverter/charger combo might be cheaper and more compact than mucking around with a solar panel and regulator - you can quickly top up the VRLA from the car battery, and you're not dependent on the weather for charging ability.
Having the charger also means you can easily charge the battery when you get back home.
condor22
Mike
There are many trains of thought re solar battery charging. My first comment is regarding the equipment used. Panels - some may know that the silicone used in panels is "grown" in a lab in a larger than needed sheet. The efficiency and quality is best at the centre of the sheet, so the more expensive panels use this area and in larger chunks, one cell of a panel might be only one piece of silicone. The residue is then usually used for cheaper panels or sold off to other panel manufacturers where they then join the smaller fragments to produce a cell and as we know, the more connections introduced the lower the efficiency. They will all produce power, the question is how much, in what conditions and for how long (panel life).
The second part of the equation is the solar controller. the cheaper is a PWM (pulse width modulation) the more expensive is MPPT (maximum power point tracker). MPPT optimises the power between the panel voltage and battery to give the maximum wattage available, which will always vary depending on solar conditions.
If you are on a budget and only want a small amount of occasional power use, modest battery size and panel size, the a PWM is fine. However if you are running a fridge and other devices from a larger battery and solar array then MPPT is the way to go. Most MPPT controllers have different charging algorithms i.e. AGM, GEL, Wet Cell and now Lithium. However I have only seen one MPPT controller that has a programable voltage for Lithium (Renogy Rover Elite). Most smaller PWM (10 A) only have one output.
The next thing to consider is solar output i.e. I have a 110 W panel it is rated at 6.24 A (Imp) and I've tested it in really good conditions at over that at 6.4 A. Over time this will reduce a little. In winter conditions at mid day, average overcast this drops to less than 2.0 A.
Taken in context of a fridge - In summer a fridge will work harder, especially in the rear of a vehicle and you will make more solar power cos of the sun shining. In winter time you may use only a 1/3 as much power for the fridge and likewise that or less solar power. So when designing a system, you need to look at worst case scenario and consider other charging options such as a DC-DC charger or 240 VAC charger from a genny.
More....
The second part of the equation is the solar controller. the cheaper is a PWM (pulse width modulation) the more expensive is MPPT (maximum power point tracker). MPPT optimises the power between the panel voltage and battery to give the maximum wattage available, which will always vary depending on solar conditions.
If you are on a budget and only want a small amount of occasional power use, modest battery size and panel size, the a PWM is fine. However if you are running a fridge and other devices from a larger battery and solar array then MPPT is the way to go. Most MPPT controllers have different charging algorithms i.e. AGM, GEL, Wet Cell and now Lithium. However I have only seen one MPPT controller that has a programable voltage for Lithium (Renogy Rover Elite). Most smaller PWM (10 A) only have one output.
The next thing to consider is solar output i.e. I have a 110 W panel it is rated at 6.24 A (Imp) and I've tested it in really good conditions at over that at 6.4 A. Over time this will reduce a little. In winter conditions at mid day, average overcast this drops to less than 2.0 A.
Taken in context of a fridge - In summer a fridge will work harder, especially in the rear of a vehicle and you will make more solar power cos of the sun shining. In winter time you may use only a 1/3 as much power for the fridge and likewise that or less solar power. So when designing a system, you need to look at worst case scenario and consider other charging options such as a DC-DC charger or 240 VAC charger from a genny.
More....
condor22
Mike
In the context of the question, running a few LED lights. The first question is how many amps or milli amps does the total lighting draw and for how long each day will you do that for. I'll give an example;
Total current draw = 2.0 amps at 12 VDC, running for 5 hours each night. The math is 2 x 5 = 10 AH.
The next part is battery size, an AGM, SRLA, GEL etc deep cycle should not be drawn deeper than 50% and preferably 25% for extended battery life. So a factor of 2 to 4.
i.e. at 25% multiply your 10 AH by 4 = 40 or at 50% multiply your 10 AH x 2 = 20. So a battery of between 20 and 40 AH will give good service for your usage.
However, I prefer to err on the conservative side by wanting 2 days of use as there might be occasions you can't charge i.e. really bad rainy weather. so you then double the battery size.
Having said all of this if your usage is half my example then you halve the battery size range.
The last part of the puzzle is solar panel size. Without getting into the science and math of it all, I use a "rule of thumb" If you have sized a 40 AH battery, then double the number to approximate panel size i.e. 40 x 2 = 80 W. Keep in mind that you are only replacing between 25-50% of the battery and my rule of thumb applies more to the 25%.
Example - My van had a 100 AH battery (I've increase this to a 130 AH since installing panels) and 2 x 100 W panels. I initially calculated my use at around 25 AH, (25% of the 100 AH) then added a diesel heater which increased my use to around 37 AH which is around 28% of the now 130 AH battery, so still in the ball park.
I go to VIC in winter and I know my panels will fill that usage generally by mid afternoon even with the larger usage and battery. Hope this helps.
(Caveat - I am using Sun Solar U.S. panels, not cheap)
Total current draw = 2.0 amps at 12 VDC, running for 5 hours each night. The math is 2 x 5 = 10 AH.
The next part is battery size, an AGM, SRLA, GEL etc deep cycle should not be drawn deeper than 50% and preferably 25% for extended battery life. So a factor of 2 to 4.
i.e. at 25% multiply your 10 AH by 4 = 40 or at 50% multiply your 10 AH x 2 = 20. So a battery of between 20 and 40 AH will give good service for your usage.
However, I prefer to err on the conservative side by wanting 2 days of use as there might be occasions you can't charge i.e. really bad rainy weather. so you then double the battery size.
Having said all of this if your usage is half my example then you halve the battery size range.
The last part of the puzzle is solar panel size. Without getting into the science and math of it all, I use a "rule of thumb" If you have sized a 40 AH battery, then double the number to approximate panel size i.e. 40 x 2 = 80 W. Keep in mind that you are only replacing between 25-50% of the battery and my rule of thumb applies more to the 25%.
Example - My van had a 100 AH battery (I've increase this to a 130 AH since installing panels) and 2 x 100 W panels. I initially calculated my use at around 25 AH, (25% of the 100 AH) then added a diesel heater which increased my use to around 37 AH which is around 28% of the now 130 AH battery, so still in the ball park.
I go to VIC in winter and I know my panels will fill that usage generally by mid afternoon even with the larger usage and battery. Hope this helps.
(Caveat - I am using Sun Solar U.S. panels, not cheap)
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