Solar panel , PV , question

[runner]

I have two 110 watt panels to install for a small off grid system. Going to pole mount them and maintain a 12 volt 1000 watt hour battery bank. Just for lighting and radio / maybe a small frig. It is a weekend place so I would think after a day the batteries should be topped off ,,, thru a solar controller of course. Question is , is it better to only leave one in the circuit during the away time to slow the charge rate ? Or possibly add a small tender type panel for use when I am not there ?

 

[RoterTeufel]

Charge controller should keep your batteries topped up (assuming your panels can meet the capacity of your batteries and draw/load of the system) and not over charged.


Have you looked at system sizing calculators that are free all over the web? Or many UTube videos like this guy who is very easy to understand:
View: https://youtu.be/uobUwjCLfok

Quick mention... 12v solar will cost you more. The guy I linked above has many videos and discusses it in his videos. However if you don't plan on expanding past your simple setup then it may be best for your situation.
YMMV.

 

[Coyote33]

You know what ever you choose won't be enough. I'd say go to 1500 or 2500 right off the bat, considering you mentioned a "fridge"?

Also, when I read "pole mount" first thing comes to mind is "tree falls on pole" or something else happening. I'd just make a sturdy cinder block or concrete base, and mount to that.

Finally, those are the thoughts of someone who knows nothing and is just having his first Sunday coffee. Total NES shot in the dark style.

 

[parabol]

You know what ever you choose won't be enough. I'd say go to 1500 or 2500 right off the bat, considering you mentioned a "fridge"?

Also, when I read "pole mount" first thing comes to mind is "tree falls on pole" or something else happening. I'd just make a sturdy cinder block or concrete base, and mount to that.

Finally, those are the thoughts of someone who knows nothing and is just having his first Sunday coffee. Total NES shot in the dark style.

You know what ever you choose won't be enough. I'd say go to 1500 or 2500 right off the bat, considering you mentioned a "fridge"?

Also, when I read "pole mount" first thing comes to mind is "tree falls on pole" or something else happening. I'd just make a sturdy cinder block or concrete base, and mount to that.

Finally, those are the thoughts of someone who knows nothing and is just having his first Sunday coffee. Total NES shot in the dark style

Put in an off grid solar system 2 years ago. 480w in panels and 440AH in AGM batteries. 60AMP controller and a 1500w converter. I designed the system to run the camp for 3 rainy days without much ability to charge. Then recharge in one day of full sun. The converter runs into a small breaker panel that feeds the camp.

We have three rooms (kitchen, dining, living room - those terms are pretty generous) with a total of 15 LEDs, a ceiling fan, and Frankenstein fridge. The fridge is the key. In my research a normal fridge used too much power so I rewired a small chest freezer to run at fridge temps (search for keezer - beer folks do this all the time, only takes a $20 digital thermostat). The efficient pump and lots of insulation make chest freezers ideal. I calculated that mine (7.5 cu ft) will run for 30 days on the battery bank I have.

There are lots of calculators online to help you plan out the main components.

 

[Vermonster]

A decade of real world experience in northern New England:
Without a backup generater to charge, you will slowly (or not so slowly) destroy lead acid batteries on solar. Why? Cloudy, short days in late fall and winter. Longest time without a full sunny day on my system, 8 days. Also, lead acid batteries need hours of absorb time, which exceeds the total daylight hours for several months.
You can make this work if you only charge and don't use system from Nov-Mar. Fully charge (can take 8-10 hours, generator for bulk stage then solar) then detach all loads and just float charge with solar; you will probably be ok. Lithium batteries are not the ea$y solution, because unless above freezing they won't charge.
To be clear, solar with a very efficient fridge can work fine in summer and early fall if you size appropriately.

 

[runner]

A decade of real world experience in northern New England:
Without a backup generater to charge, you will slowly (or not so slowly) destroy lead acid batteries on solar. Why? Cloudy, short days in late fall and winter. Longest time without a full sunny day on my system, 8 days. Also, lead acid batteries need hours of absorb time, which exceeds the total daylight hours for several months.
You can make this work if you only charge and don't use system from Nov-Mar. Fully charge (can take 8-10 hours, generator for bulk stage then solar) then detach all loads and just float charge with solar; you will probably be ok. Lithium batteries are not the ea$y solution, because unless above freezing they won't charge.
To be clear, solar with a very efficient fridge can work fine in summer and early fall if you size appropriately.

How long would charging take with generator ? If the panels will recharge in a five hour window during full sun , will running the generator and charging for the same time work ? I would assume the charger would need to produce the same power ,,,,,

 

[Vermonster]

How long would charging take with generator ? If the panels will recharge in a five hour window during full sun , will running the generator and charging for the same time work ? I would assume the charger would need to produce the same power ,,,,,

Depends on the bulk charge rate
(capacity of charge controller and settings) and generator size. But many deep cycle lead acid batteries cant fully recharge in 5 hours. Look at the battery spec and calculate the absorb time. In most cases that alone will be 3-5 hours. In winter you will be lucky to get 5 hours of good sun. Good approach is to bulk charge with generator early morning then you have all day to complete absorb on solar.

 

[runner]

Depends on the bulk charge rate
(capacity of charge controller and settings) and generator size. But many deep cycle lead acid batteries cant fully recharge in 5 hours. Look at the battery spec and calculate the absorb time. In most cases that alone will be 3-5 hours. In winter you will be lucky to get 5 hours of good sun. Good approach is to bulk charge with generator early morning then you have all day to complete absorb on solar.

That is the future plan ,,,, to have the generator run on days with low sun and no wind ,,,, I plan on running a 5k diesel to be the back up power. What spec calls out the absorption rate ?

 

[Vermonster]

That is the future plan ,,,, to have the generator run on days with low sun and no wind ,,,, I plan on running a 5k diesel to be the back up power. What spec calls out the absorption rate ?

Battery charge parameters should be available from the battery manufacturer. For example, here is Calculating Proper Charge Settings for Rolls Flooded Lead-Acid Batteries

The issue in winter is that you will need to run the generator frequently to fully complete the charge and avoid sulfation. Depending on how much power you use, you can quickly get to where you never fully charge even when it's sunny. The days are just too short.

 

[pastera]

Look at LFP Batteries - cheaper than LA batteries over time for your usage

 

[VTHunter]

Shamelessly hijacking the thread - kinda...

I am seeking 4 LC16 HCL (Interstate) equivalent batteries for an off-grid system. I am unable to obtain these from Interstate, despite having contacted 3 distribution warehouses. They apparently are stalled on the way from China. I have also tried US Battery & Trojan distributors.

Does anyone have a source for these monsters in the New England area? I can pick up & have cores.