diy solar

diy solar

few questions about solar power....

corporal_Canada

corporal_Canada

New Member
Joined
Aug 29, 2023
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264
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Philippines
bonjour/hello, my name is Christopher from the arrogant french part of Canada(please forgive me if my English isnt flawless), however i moved to the Philippines last year and all this sun smacking me on the top of my gorgeous head got me thinking, why am i not using it... i got 3x 300+ solar panels that produce roughly 100watts each at minimum...... im on my 3rd inverter... i hav a 12v SLA battery that claims to be 100ah.... (however it is very very chinese... sorry before i continue id like to ask 1 simple question ... i learned in basic Tesla Engineering class that electrons only flow 1 direction.....so if all the solar panels are going to the pos and neg terminal of a battery.. how can you expect to draw anything from that battery by clamping an inverter onto those exact terminals ???

anyways.. since the battery only serves to regulate the voltage and / or store a bit of power... am i right to assume that the battery size makes no difference ? as long as it is 12V.. i can just connect any inverter to it...(ie.. 12v car batt or 12v motorcycle batt) and the inverter will power my 200wh pc as long as there is yummy sunlight(and awesome monitor).. .. and possibly a very petite refridgerator ???as a percaution, i did order a UPS, to protect the pc from commiting seppuku.. i do have a charge controller.. one of those tiny blue chinese ones ... but last time i reconnected everything, the lcd screen on the charge controller refuses to come on.. leading me to believe that my 12v 100ah batt is over....
 
The solar panels are like a DC generator, you can power your laptop with them and any excess will go into the battery, assuming the battery is not yet full. If you need some hand holding, drop me a line, maybe we can both learn.
 
corporal_Canada said:
... sorry before i continue id like to ask 1 simple question ... i learned in basic Tesla Engineering class that electrons only flow 1 direction.....so if all the solar panels are going to the pos and neg terminal of a battery.. how can you expect to draw anything from that battery by clamping an inverter onto those exact terminals ???

...
Click to expand...
Your PV charge controller, battery and loads are all connected in common. Even if separate wires are used. Since a higher voltage will create a current flow to a lower voltage whatever is supplying the higher voltage acts as the supply to the loads. In the instance of solar panels they produce voltage when in sunlight and can supply a load as long as the power they produce is enough to maintain voltage. Batteries produce a voltage due to a chemical reaction inside. It gets depleted with use and as it does the ability to supply voltage drops. It can be restored through charging. Charging a battery requires a higher voltage than the chemistry of the battery is producing.

Thus you turn on a load being supplied by the DC common bus. If there is not enough PV to supply it the voltage drops to low enough the battery internal voltage is higher and begins to add to the current requirement of the load. If the batteries charge is low (thus lower battery voltage) the PV charge controller attempts to charge it from solar by raising voltage. Batteries are considered storage and PV (or grid, gas generators) are supply.
 
Mattb4 said:
Your PV charge controller, battery and loads are all connected in common. Even if separate wires are used. Since a higher voltage will create a current flow to a lower voltage whatever is supplying the higher voltage acts as the supply to the loads. In the instance of solar panels they produce voltage when in sunlight and can supply a load as long as the power they produce is enough to maintain voltage. Batteries produce a voltage due to a chemical reaction inside. It gets depleted with use and as it does the ability to supply voltage drops. It can be restored through charging. Charging a battery requires a higher voltage than the chemistry of the battery is producing.

Thus you turn on a load being supplied by the DC common bus. If there is not enough PV to supply it the voltage drops to low enough the battery internal voltage is higher and begins to add to the current requirement of the load. If the batteries charge is low (thus lower battery voltage) the PV charge controller attempts to charge it from solar by raising voltage. Batteries are considered storage and PV (or grid, gas generators) are supply.
Click to expand...
sooo.. a motorcycle battery wont cut it ?
 
Battery size does matter as the battery will see most of the load when say cloud passes over or you forget to turn it off when the sun drops below the trees.

Lead acid batteries are a terrible technology. First off you can only discharge them to 50% before you start significantly shortening their life. Secondly the ratings are over 20 hours and drop off significantly at higher discharge rates. For example a 20hr rate for a 100Ah battery is only 5 amps or 5x12v = 60watts. Drawing more than that 60watts will reduce the capacity of the battery significantly below that 50Ah.

You really need to look closely at the datasheets for your batteries and treat them accordingly.

In my experience here in Canada once you go with a good brand and properly size lead acid batteries your into the cost of Lithium Iron batteries which last a decade longer. The best deal I've found currently is AOLithium as they have good prices to start with and free shipping from within Canada.

Imagine batteries and panels as buckets of water and voltage is the elevation. Current will flow from the higher voltage panels to the lower voltage batteries when connected in parallel. The difference in voltage controls how much current flows.

You really shouldn't connect them directly together without a charge controller. The charge controller at the very least will limit the voltage and current to what the battery needs to charge properly. Better MPPT chargers will use DC switching to pump up the current and down the voltage to find the point of maximum power transfer. It's kind of like a gear box but rather than trading off rpm and torque it's voltage and current. Cheaper PWM chargers just basically turn on/off the panels very quickly to limit the voltage and current so you never get the full potential power of the panel. Better charge controllers will also do different charge phases based on the batteries state(bulk, absorption, float and equalize). Cheap charge controller basically only do float. That said, these charge phases really only apply to lead acid batteries.

The amount of power coming from the panels will follow a bell curve through out the day. You will only get the rated power of the panels in the middle of the day. So your panels need to be significantly bigger than your load to charge the batteries and run the load in the middle of the day. Then in the morning and evening your batteries can help make up the difference.

UPS are designed for very occasional use and for fairly short amounts of time. They will not last very long being cycled daily.

A fridge is a significant load on a solar system as it runs 24 hours a day. Very efficient non frost free 12v fridges use around 500Wh a day. So you need 500Wh/12v = 42Ah of useable battery capacity just for the fridge per day. Really you want to atleast double if not triple that for when there are cloudy days. A good frost free 120v fridge uses something like 1100Wh/day at best.

48v systems start to look very attractive when you start to consider the cost of components on larger solar systems. The cost is usually in current handling. So a 80A charge controller is similar in price between 12v, 24v and 48v but at 48v you have 4x the power.

These days panels are getting very cheap. Larger ~545watt panels can be had for as little as 25cents a watt. So it's affordable to put in a massive array if you have the space.

So much to just go on and on with....
 
during daylight hours.. the pos and neg terminal read 18-20 volts.. during non daylight hours.. it reads.. 13-14volts.. did i add too much battery acid ?
 
corporal_Canada said:
sooo.. a motorcycle battery wont cut it ?
Click to expand...

corporal_Canada said:
during daylight hours.. the pos and neg terminal read 18-20 volts.. during non daylight hours.. it reads.. 13-14volts.. did i add too much battery acid ?
Click to expand...

Hi @corporal_Canada

This might help you ( you might find a Francais Version );


You have to match up your equipment, & as others have referened you need to get performance specifications from the manufacturers of the equipment ,,, batteries, chargers, solar panels

A motorcycle battery “could” cut it however you would need to dial in your solar charger to the charge profile required for that specific battery. I would think a motorcycle battery would have very limited storage capacity.
 
LordGarak said:
Battery size does matter as the battery will see most of the load when say cloud passes over or you forget to turn it off when the sun drops below the trees.

Lead acid batteries are a terrible technology. First off you can only discharge them to 50% before you start significantly shortening their life. Secondly the ratings are over 20 hours and drop off significantly at higher discharge rates. For example a 20hr rate for a 100Ah battery is only 5 amps or 5x12v = 60watts. Drawing more than that 60watts will reduce the capacity of the battery significantly below that 50Ah.

You really need to look closely at the datasheets for your batteries and treat them accordingly.

In my experience here in Canada once you go with a good brand and properly size lead acid batteries your into the cost of Lithium Iron batteries which last a decade longer. The best deal I've found currently is AOLithium as they have good prices to start with and free shipping from within Canada.

Imagine batteries and panels as buckets of water and voltage is the elevation. Current will flow from the higher voltage panels to the lower voltage batteries when connected in parallel. The difference in voltage controls how much current flows.

You really shouldn't connect them directly together without a charge controller. The charge controller at the very least will limit the voltage and current to what the battery needs to charge properly. Better MPPT chargers will use DC switching to pump up the current and down the voltage to find the point of maximum power transfer. It's kind of like a gear box but rather than trading off rpm and torque it's voltage and current. Cheaper PWM chargers just basically turn on/off the panels very quickly to limit the voltage and current so you never get the full potential power of the panel. Better charge controllers will also do different charge phases based on the batteries state(bulk, absorption, float and equalize). Cheap charge controller basically only do float. That said, these charge phases really only apply to lead acid batteries.

The amount of power coming from the panels will follow a bell curve through out the day. You will only get the rated power of the panels in the middle of the day. So your panels need to be significantly bigger than your load to charge the batteries and run the load in the middle of the day. Then in the morning and evening your batteries can help make up the difference.

UPS are designed for very occasional use and for fairly short amounts of time. They will not last very long being cycled daily.

A fridge is a significant load on a solar system as it runs 24 hours a day. Very efficient non frost free 12v fridges use around 500Wh a day. So you need 500Wh/12v = 42Ah of useable battery capacity just for the fridge per day. Really you want to atleast double if not triple that for when there are cloudy days. A good frost free 120v fridge uses something like 1100Wh/day at best.

48v systems start to look very attractive when you start to consider the cost of components on larger solar systems. The cost is usually in current handling. So a 80A charge controller is similar in price between 12v, 24v and 48v but at 48v you have 4x the power.

These days panels are getting very cheap. Larger ~545watt panels can be had for as little as 25cents a watt. So it's affordable to put in a massive array if you have the space.

So much to just go on and on with....
Click to expand...
the fridge (called REF here) claims to only pull 54 watts and naturally i will plug it into land power when the sun sets... you did read the part about me not being in Canada anymore right ?.... as for the "life" of the battery, i couldnt care less.. a motorcycle battery can run for less than 10$ each here in Asia...... i just want any of my inverters to actually turn on now.. so i can use some of those solar panels outside my window... since Philippines experiences many power outages and has alot of "static" in its power... a UPS is very common around here..... since id like to use a cheaper battery this time, i will plug both my pc and the refridgerator to land power..during the evening and night.. and either something isnt connected correctly or the battery has gone bad... but.. the charge controller has a blank lcd display and all 3 inverters will not stay on continously... i added battery acid to all 4 ports on top of the battery... but.. that only brought it back from 9v to 13-14v.. if i test my batteries right now with zero sunlight 10 pm here at the moment.....it reaches 12.45 volts.. tells me the battery is somewhat alive...... sorry, i wont test the amperage because doing that had 1 multimeter terminal explode in my hand and i destroyed another multimeter.. im still figuring out the fused and UNfused part of that proceedure :/
 
RV8R said:
Hi @corporal_Canada

This might help you ( you might find a Francais Version );


You have to match up your equipment, & as others have referened you need to get performance specifications from the manufacturers of the equipment ,,, batteries, chargers, solar panels

A motorcycle battery “could” cut it however you would need to dial in your solar charger to the charge profile required for that specific battery. I would think a motorcycle battery would have very limited storage capacity.
Click to expand...
that does resemble a motorcycle battery :)....
 
Bongbong said:
The solar panels are like a DC generator, you can power your laptop with them and any excess will go into the battery, assuming the battery is not yet full. If you need some hand holding, drop me a line, maybe we can both learn.
Click to expand...
wow, you phrased that so beautifully...i need a mommy grip handholding :)
 
RV8R said:
That would be my guess as well ,,, post the specs of your equipment @corporal_Canada

But as @GXMnow stated ,,, you are probably cooking your battery.
Click to expand...
i would be happy to however.. nothing is colour coded at the moment.. it is all based on my impeccable memory... black cables going everywhere....

transfering photo now.. keep in mind.. it is 11pm here.. im aware thast im cooking the battery.. i have no way to draw from the 12v battery as all my inverters refuse to turn on...IMG_0966.JPGand if you see a nude french Canadian in any reflection.. get off my back its 27c here...... the big block on top is the last inverter i ordered to see if the cyan inverter on the bottom there died or not... the chernobyl looking one on top is obviously rated at 300w.. most likely NOT sinewave... and the cyan one on the bottom is rated at 1000watts.. modified sine wave.. but.. that shouldnt matter anymore since i will be plugging in my pc to the ups directly .. i can only assume that it comes equipped with a sine wave AC output..... the black box on the left is what i use for lighting... solar charged of course.... but please just answer 1 question... can i connect all that to any 12v battery ?.. just to have any inverter chirp back to life to power my pc during the daytime ONLY... and possibly even my tiny refridgerator....
 
corporal_Canada said:
i would be happy to however.. nothing is colour coded at the moment.. it is all based on my impeccable memory... black cables going everywhere....

transfering photo now.. keep in mind.. it is 11pm here.. im aware thast im cooking the battery.. i have no way to draw from the 12v battery as all my inverters refuse to turn on...View attachment 204235and if you see a nude french Canadian in any reflection.. get off my back its 27c here...... the big block on top is the last inverter i ordered to see if the cyan inverter on the bottom there died or not... the chernobyl looking one on top is obviously rated at 300w.. most likely NOT sinewave... and the cyan one on the bottom is rated at 1000watts.. modified sine wave.. but.. that shouldnt matter anymore since i will be plugging in my pc to the ups directly .. i can only assume that it comes equipped with a sine wave AC output..... the black box on the left is what i use for lighting... solar charged of course.... but please just answer 1 question... can i connect all that to any 12v battery ?.. just to have any inverter chirp back to life to power my pc during the daytime ONLY... and possibly even my tiny refridgerator....
Click to expand...
Most UPS go into complete bypass when not running on the internal battery. So the modified sine wave will pass straight through.

An online UPS will convert the incoming power to DC and back to AC all the time, but they are typically much more expensive than a normal UPS.

Your likely overvolting the inverters running them directly off the solar panels without a charge controller. I wouldn't expect a 12v inverter to handle much more than 15volts.
 
LordGarak said:
Most UPS go into complete bypass when not running on the internal battery. So the modified sine wave will pass straight through.

An online UPS will convert the incoming power to DC and back to AC all the time, but they are typically much more expensive than a normal UPS.

Your likely overvolting the inverters running them directly off the solar panels without a charge controller. I wouldn't expect a 12v inverter to handle much more than 15volts.
Click to expand...
well, i believe i mentioned that the 2 terminals on the battery read 18-20 volts during daytime...

i also mentioned that the solar panels arent connected to the charge controller.. because it is either defective or the battery is dead
so my theory is that the battery reflects what the solar panels are feeding it... 18-20volts
 
Last edited:
Your battery is ruined. A charge controller will limit current or turn off when the voltage goes above the bulk voltage of the battery. That keeps it from cooking. When the voltage goes that high, it boils the electrolyte and the battery is killed.
 
GXMnow said:
Your battery is ruined. A charge controller will limit current or turn off when the voltage goes above the bulk voltage of the battery. That keeps it from cooking. When the voltage goes that high, it boils the electrolyte and the battery is killed.
Click to expand...
exactly.. i need new battery... and im asking if i can use a simple 12v motorcycle battery.. just to tap into 30% of the power coming in.. please observe the video if i can figure out how to link it


 
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