Need Some Assistance Trying to Design a Very Small Solar Panel Setup

[hvacskills]

Well that's kinda what I was thinking. Now I carried it out a little further so someone correct me if I did the math in my head wrong but if I leave the outside lights for 10 hours a night average @ $.105 / kWh it will only cost me a quarter a day, or $7.50/month. Seems like I would have to add a lot more to the solar to make it worth while. Now there actually are more lights that are wired into the panel for solar but we only use lights in the room we are in so not a lot of demand there. I do want to do a flag light so that will add and I have a gazebo that I want to build and put strings of light on which will add, then there is the out building with lights and ceiling fans that if I put the fans on it would add quite a bit of load but it seems like they are only 2 amps each max. I see my biggest gain in the hot water. Being able to keep the out building above 40 in the winter will be great as well as what gets added to the house plus domestic hot water.

what is the total amount of wattage / per hour that you would like to run off solar in a 24 hour period ?

say a light bulb is 25 watts, and you want to run it 4 hours in one day, that would be 100 watts in a 24 hour period .....

just curious what size system / batteries you would be needing .....

[hvacskills]

project is somewhat on hold until the battery situation can be researched further .....

still leaning towards the two different systems as mentioned earlier, and building lithium 18650 battery packs as also mentioned




evaluating costs / material / design .... leaning toward building several smaller battery packs ( 25.9 v 30 amp ) and placing them parallel opposed to larger battery packs, this will provide redundancy and cheaper replacement for each battery pack in the event of battery pack failure .... a 12 volt 100 amp lithium battery is around $ 1,000, x 4, that is out of the question ....

[Lawrosa]

Your wasting your time..And may not fully understand totally. Slow down.

Batterys are based on amp hours. They are rated this way based on a 5 amp draw for 20 hours.

So a golf cart battery 6 volts is 225 amp hours. Hook two in series it becomes 12v but still 225 ah.

The 12 volts I was using were 75 ah each. I had three. Hooked in parallel they are still 12v but become 225 ah.

There is such thing as purkets effectwhen drawing high amps from a batt. As battery drains its lasts less time then rated.

Heavy lead 6 volts can run longer with low draw. Heavy plates. Less voltage drop. Try to pull large load and you will be voltage drop. Possibly below inverters ability and it will kick off on low voltage.

12 volt batts can run a micro wave say with less voltage drop but will die quicker.


So...

225 ah is really 110 ah. Thats 50% that your supposed to draw them down. 110 ah now you can run a 5 amp load for only 10 hours or a 2.5 amp load for 20 hours..

say I want to run a coffee pot off my inverter. Thats 900 watts. But through the inverter and from the 12 volt batterys I will be drawing 75 amps from them....

Thats 75ampos... yes.

That means I can make one pot of coffee and if the coffee maker was on for the total hour the batts are almost dead per se. And lest not forget voltage drop while doing this..

How solar will help.

You need to make said coffee in the day . The charge controller will supplement the batterys. So instead of drawing 75 amps from batts the solar with the panel set up I explained several posts ago will help with say 30 amps. And thats if its nice and sunny.

So the solar helps with 30 amps - 75 amps = 45 amps only being drawn from batts.

The other thing with the solar charge controller is how to charge types of batterys..

Bulk charging on lead acid deep cycles batts are 14.8 volts. After bult the amps taper. But you still charge at 14.8 or so. When the amps get to 2 amps or so you can go into float mode.

Also the said mppt charge controllers make more amps then what the panels are rated at. Since you have two panels and 60 volts going to the controller the batts only need 14.8.. Where does the extra volts go? The controller turns it into amps.

You have a bit to learn and I would do more research before you start buying stuff.

So say you have a set up with 225 ah batts. ( 1/2 is 110ah) Batts are fully charged. Its night time. You turn on a 100 watt light bulb and your computer thats 200 watts.

300 watts / 12 volts is 25 amp. 110ah/25 amps = 4.4 hours. You can run that light and computer for about 4 hours.

Probably less due to Peukert's law and the losses through the inverter converting 12 volts to 120volts. They are only about 85% efficient so your losing 15% or so.

So dwell on this info for a while

[Lawrosa]

These are very high loads.

Here is my draw testings on batts with microwave..

https://www.youtube.com/watch?v=wz2ttT8fFLc

And my and toaster oven test exaggerated amp draw..


https://www.youtube.com/watch?v=7p-oNT8YDIs&t=6s

PS. The trouble with sealed batts is you only know the state of charge based on voltage.. Wet cell you get accurate readings with a hydrometer.

[DavidDeBord]

Your wasting your time..And may not fully understand totally. Slow down.

Batterys are based on amp hours. They are rated this way based on a 5 amp draw for 20 hours.

So a golf cart battery 6 volts is 225 amp hours. Hook two in series it becomes 12v but still 225 ah.

The 12 volts I was using were 75 ah each. I had three. Hooked in parallel they are still 12v but become 225 ah.

There is such thing as purkets effectwhen drawing high amps from a batt. As battery drains its lasts less time then rated.

Heavy lead 6 volts can run longer with low draw. Heavy plates. Less voltage drop. Try to pull large load and you will be voltage drop. Possibly below inverters ability and it will kick off on low voltage.

12 volt batts can run a micro wave say with less voltage drop but will die quicker.


So...

225 ah is really 110 ah. Thats 50% that your supposed to draw them down. 110 ah now you can run a 5 amp load for only 10 hours or a 2.5 amp load for 20 hours..

say I want to run a coffee pot off my inverter. Thats 900 watts. But through the inverter and from the 12 volt batterys I will be drawing 75 amps from them....

Thats 75ampos... yes.

That means I can make one pot of coffee and if the coffee maker was on for the total hour the batts are almost dead per se. And lest not forget voltage drop while doing this..

How solar will help.

You need to make said coffee in the day . The charge controller will supplement the batterys. So instead of drawing 75 amps from batts the solar with the panel set up I explained several posts ago will help with say 30 amps. And thats if its nice and sunny.

So the solar helps with 30 amps - 75 amps = 45 amps only being drawn from batts.

The other thing with the solar charge controller is how to charge types of batterys..

Bulk charging on lead acid deep cycles batts are 14.8 volts. After bult the amps taper. But you still charge at 14.8 or so. When the amps get to 2 amps or so you can go into float mode.

Also the said mppt charge controllers make more amps then what the panels are rated at. Since you have two panels and 60 volts going to the controller the batts only need 14.8.. Where does the extra volts go? The controller turns it into amps.

You have a bit to learn and I would do more research before you start buying stuff.

So say you have a set up with 225 ah batts. ( 1/2 is 110ah) Batts are fully charged. Its night time. You turn on a 100 watt light bulb and your computer thats 200 watts.

300 watts / 12 volts is 25 amp. 110ah/25 amps = 4.4 hours. You can run that light and computer for about 4 hours.

Probably less due to Peukert's law and the losses through the inverter converting 12 volts to 120volts. They are only about 85% efficient so your losing 15% or so.

So dwell on this info for a while

A lot of Interesting Data Lawrsa,... Do You install these Systems?

[Lawrosa]

A lot of Interesting Data Lawrsa,... Do You install these Systems?

No. Its just a hobby for my own personal use. I probably should install them. Ive seen some RV hack jobs for sure...

[hvacskills]

You have a bit to learn and I would do more research before you start buying stuff.

thank you for your assistance, however your input is no longer needed, post 82 clearly stated the project was on hold until battery type was further investigated and selected and post 79 clearly stated the understanding of battery amp hours

[Lawrosa]

thank you for your assistance but I do not need your input, post 82 clearly stated the project was on hold until battery type was further investigated and selected and post 79 clearly stated the understanding of battery amp hours

Holy F78k...Ill give you no further input.... good luck. Rude

[DavidDeBord]

No. Its just a hobby for my own personal use. I probably should install them. Ive seen some RV hack jobs for sure...

[DavidDeBord]

thank you for your assistance, however your input is no longer needed, post 82 clearly stated the project was on hold until battery type was further investigated and selected and post 79 clearly stated the understanding of battery amp hours

What brought that on?!?

[BNME8EZ]

Your wasting your time..And may not fully understand totally. Slow down.

Batterys are based on amp hours. They are rated this way based on a 5 amp draw for 20 hours.

So a golf cart battery 6 volts is 225 amp hours. Hook two in series it becomes 12v but still 225 ah.

The 12 volts I was using were 75 ah each. I had three. Hooked in parallel they are still 12v but become 225 ah.

There is such thing as purkets effectwhen drawing high amps from a batt. As battery drains its lasts less time then rated.

Heavy lead 6 volts can run longer with low draw. Heavy plates. Less voltage drop. Try to pull large load and you will be voltage drop. Possibly below inverters ability and it will kick off on low voltage.

12 volt batts can run a micro wave say with less voltage drop but will die quicker.


So...

225 ah is really 110 ah. Thats 50% that your supposed to draw them down. 110 ah now you can run a 5 amp load for only 10 hours or a 2.5 amp load for 20 hours..

say I want to run a coffee pot off my inverter. Thats 900 watts. But through the inverter and from the 12 volt batterys I will be drawing 75 amps from them....

Thats 75ampos... yes.

That means I can make one pot of coffee and if the coffee maker was on for the total hour the batts are almost dead per se. And lest not forget voltage drop while doing this..

How solar will help.

You need to make said coffee in the day . The charge controller will supplement the batterys. So instead of drawing 75 amps from batts the solar with the panel set up I explained several posts ago will help with say 30 amps. And thats if its nice and sunny.

So the solar helps with 30 amps - 75 amps = 45 amps only being drawn from batts.

The other thing with the solar charge controller is how to charge types of batterys..

Bulk charging on lead acid deep cycles batts are 14.8 volts. After bult the amps taper. But you still charge at 14.8 or so. When the amps get to 2 amps or so you can go into float mode.

Also the said mppt charge controllers make more amps then what the panels are rated at. Since you have two panels and 60 volts going to the controller the batts only need 14.8.. Where does the extra volts go? The controller turns it into amps.

You have a bit to learn and I would do more research before you start buying stuff.

So say you have a set up with 225 ah batts. ( 1/2 is 110ah) Batts are fully charged. Its night time. You turn on a 100 watt light bulb and your computer thats 200 watts.

300 watts / 12 volts is 25 amp. 110ah/25 amps = 4.4 hours. You can run that light and computer for about 4 hours.

Probably less due to Peukert's law and the losses through the inverter converting 12 volts to 120volts. They are only about 85% efficient so your losing 15% or so.

So dwell on this info for a while

If I am hearing you correctly it sounds like you are saying that rather than try to store the power it would be better to just put it back on the grid and use it as on offset for when the sun doesn't shine. I was thinking my project wasn't big enough to warrant the expense but maybe the expense would not be as great because of less storage needed.

[BBeerme]

If I remember correctly, this whole project started to be able to deal with when the grid goes down. Which, if I remember correctly, is a fairly common occurrence. So battery storage has to be a key element of the project.

Though, feeding back into the grid could be utilized in order to recoup some or all of the expenses.

[hvacskills]

went ahead and ordered equipment, going with two separate systems as mentioned earlier ( 2 - 600 watt systems @ 24 volts from panels / controllers / batteries )

system one : TV, router, modem, laptops, LED lighting, and whatever else can be squeezed onto the system ... all the lower load devices

system two : refrigerator, basement dehumidifier, coffee maker, microwave .... might even be able to handle a washing machine in a pinch, but that is still to be determined ... all the higher load devices

equipment :

solar panels : 4 - Live Solar 300 watts panels ..... went with polycrystalline panels even though they are slightly less efficient than monocrystalline panels, supposedly if a monocrystalline panel is slightly covered / obscured the entire panel can shut down, supposedly that is not the case with polycrystalline panels, figured ice / snow may be an issue

https://www.homedepot.com/p/Live-Sol...300W/306246905


2 - Renogy Rover Li 24-Volt 40 Amp MPPT Solar Charge Controller with Bluetooth Module .....
40 amp controller should handle the amperage with plenty of headroom, figured less wear on the controller ( 2- 300 watt panels @ 24 = 25 amps ), and allow for an additional 300 watt panel in the future ( spec sheet says controller can handle 1,040 watts @ 24 volts from panels ), 16 ' x 16 ' roof trying to add additional panels may be tight

https://www.homedepot.com/p/Renogy-R...0-BT/308730139


2 - Renogy12-Volt 200Ah Deep Cycle Pure GEL Battery ( hopefully these can be placed in series, will inquire ) ..... batteries, batteries, batteries, what do you do here ? pros and cons to the different battery choices ..... not sure this is the best choice of batteries, and the 2 will only be large enough to operate one system, but they are rated at 1,000 cycles and regular lead acid are only rated at 500 cycles, double the price but double the life, plus no venting or maintenance issues ..... going into the spring / summer / fall so hopefully the long term battery solution will be resolved before next fall .. still looking into possibly building a few battery packs but still not sure, ideally it would be nice to go lithium iron phosphate, those are expensive but some have up to 5,000 cycles and can take real heavy loads without damaging the battery

https://www.homedepot.com/p/Renogy-1...-200/302560800


that leaves the inverters, tracking down 2 - 24 volt inverters should not be that difficult but will need to research them also, supposedly full sign wave inverters are recommended

figure once everything is up and running get a better idea of what will be needed as far as batteries, 200 amps should be a decent start

thanks for all of the input ....

[hvacskills]

If I remember correctly, this whole project started to be able to deal with when the grid goes down. Which, if I remember correctly, is a fairly common occurrence. So battery storage has to be a key element of the project.

Though, feeding back into the grid could be utilized in order to recoup some or all of the expenses.

do you know about solar systems ?

[BBeerme]

Yeah. They take a lot of sunshine, then turn it into a little bit of electricity.

do you know about solar systems ?

[hvacskills]

Yeah. They take a lot of sunshine, then turn it into a little bit of electricity.

they take in a lot of sunshine in Cali ...... lol

[BBeerme]

When we have power outages, if you're in a 'major' city, the power usually gets restored pretty quick.

If you are in the mountains, it can be a much longer wait. Because, obviously, if you have a million without power, that takes precedent over a thousand scattered around the hills.

So those in the hills will (can) have a generator for back up. Most of those will run off of propane or natural gas. The two different 'styles' of install will be 1) hard wired to specific critical outlets, or 2) an A/B disconnect switch tied into their main breaker panel.

Personally, I've never seen battery backup on a solar system. Though I do hear them advertised on the radio here and there.

[BNME8EZ]

When we have power outages, if you're in a 'major' city, the power usually gets restored pretty quick.

If you are in the mountains, it can be a much longer wait. Because, obviously, if you have a million without power, that takes precedent over a thousand scattered around the hills.

So those in the hills will (can) have a generator for back up. Most of those will run off of propane or natural gas. The two different 'styles' of install will be 1) hard wired to specific critical outlets, or 2) an A/B disconnect switch tied into their main breaker panel.

Personally, I've never seen battery backup on a solar system. Though I do hear them advertised on the radio here and there.

Could this be because Cali wants to encourage people to put power on the grid rather than being self contained?

[BBeerme]

I think it has more to do with the shear expense of the batteries. Then factor in the life span of the batteries, and that cost goes up dramatically.

Could this be because Cali wants to encourage people to put power on the grid rather than being self contained?

[hvacskills]

batteries pretty much do throw a wrench into the works as far a house system, probably why people just feed back into the grid, no investment in batteries that need to be replaced, plus a return on the cost of the rest of the equipment ...