Charge Controller

[njoelhickson]

Hello everyone. I am very new to solar and I am working on building my first array. I purchased 10 used 250w panels from San Tan Solar. The panels have not yet shipped but I am estimating the expected output on the low end at about 210 watts per panel for a total of 2100 watts. The formula I have seen for charge controllers is wattage (2100) divided by the voltage of the battery bank (I expect to go with a 24v system). That gives me a total of 87.5 amps. So I believe that I need a 100 am charge controller. Is that accurate?

Any other information that you are willing to share with me would be most welcome. I have been quoted about $500 for a K2 rack system so that I can mount it up on my roof. Your thoughts on that would be appreciated as well. Is there a better bang for my buck when it comes to a rack system or is K2 the way to go, and is that a decent price?

I intend to start out simple. Probably a couple of AGM automobile batteries and an off grid setup in my garage that I hope to expand over time into a grid tie system that will provide power to my entire home, but I want to start out simple and grow as I learn more.

Thank you.

 

[yodamota]

Hello everyone. I am very new to solar and I am working on building my first array. I purchased 10 used 250w panels from San Tan Solar. The panels have not yet shipped but I am estimating the expected output on the low end at about 210 watts per panel for a total of 2100 watts. The formula I have seen for charge controllers is wattage (2100) divided by the voltage of the battery bank (I expect to go with a 24v system). That gives me a total of 87.5 amps. So I believe that I need a 100 am charge controller. Is that accurate?
Thank you.

Looks good. Which charge controller were you looking to get?

Wish i could help you on the racking. There must be many threads on here about the subject. I have simple wood racking, attached to L brackets. With threaded rod in the rock

 

[seneysolar]

Hello everyone. I am very new to solar and I am working on building my first array. I purchased 10 used 250w panels from San Tan Solar. The panels have not yet shipped but I am estimating the expected output on the low end at about 210 watts per panel for a total of 2100 watts. The formula I have seen for charge controllers is wattage (2100) divided by the voltage of the battery bank (I expect to go with a 24v system). That gives me a total of 87.5 amps. So I believe that I need a 100 am charge controller. Is that accurate?

You will have to do some calcs on open circuit voltage and panel arrangement. What will your OCV be at the input to the controller? Then Id look at the Midnite Classic line of charge controllers or Victron.

I intend to start out simple. Probably a couple of AGM automobile batteries

Watch the max charge rate for AGM. Typical might be .2 x capacity. If only using say two of the 100ah12v in series, max charge rate will be around 20A. Feeding them with 90A of charge current after running them down will be a problem. If you want AGM batteries intended for this type of use, Look at something like the Full River DC400-6. (4 in series) - the idea being a larger capacity to match your solar array.

and an off grid setup in my garage that I hope to expand over time into a grid tie system that will provide power to my entire home, but I want to start out simple and grow as I learn more.

I prefer 24V systems but if you are looking to expand to a whole home grid tie setup, you should consider doing 48V right now.

 

[DIYrich]

Watch the max voltage and amps of the pv on the charge controller. Make sure you can configure the strings in a way to match the controller.