Hello

[Pepite]

Hello everyone! I am new to this forum and I already have a solar power system for my cabin but I want to add some panels to it. I am not sure where I should ask the questions I have. I would appreciate any help to guide me in the right direction.
thanks

 

[Horsefly]

The more info you can post, the better the advice you will get. Explain in detail what you current system includes (Solar Charge Controller, Inverter, Battery size, what panels you already have), as well as your current loads, and why you think you need more panels.

 

[Pepite]

My existing system is12v and includes: 4x120w panels with a 30a charge controler with 8 x 6v / 210ah and a xantrex freedom marine 3000w inverter charger and a xantrex link1000remote controler.
This system is for a duplex cabin and supply power for both sides for 2 tvs, lights, internet, limited use of microwaves , charger for ipads, phones and small tools batteries as needed.
I want to add 4 x 250w panels to this system that will charge at low light like cloudy days unlike the existing ones.
I am not sure how to go about it. Can I still use the 4 x 120w alongside the new ones? Or should I just use the new ones?
obviously I need another charge controler for the new ones but I am not sure what I should use (size)
I am not an electrician but I understand a little bit (very basic)
any help is appreciated!
thanks!

 

[Horsefly]

You can use the existing panels along with new panels, but you'll need a separate charge controller for the two new ones, as you said. As it stands now you have a pretty big battery bank (4 * 210Ah = 840Ah, X 12 = 10kWh), and not enough solar to charge it. So I think more panels is a good idea.

The 250w on the new panels is what I refer to as "nameplate" rated. That is the rating under STC (Standard Test Conditions). Almost no one ever sees the full rating at STC, but rather something closer to 75-80% of the nameplate rating. Still, it would be good to size your charge controller for the full nameplate rating of 1000W (4 x 250w). 1000W / 12 = 83 in a 100% efficient controller. Even with a high efficiency controller you wont see more than 80A, so an MPPT charge controller rated 80A or higher should be fine.

 

[Pepite]

You can use the existing panels along with new panels, but you'll need a separate charge controller for the two new ones, as you said. As it stands now you have a pretty big battery bank (4 * 210Ah = 840Ah, X 12 = 10kWh), and not enough solar to charge it. So I think more panels is a good idea.

The 250w on the new panels is what I refer to as "nameplate" rated. That is the rating under STC (Standard Test Conditions). Almost no one ever sees the full rating at STC, but rather something closer to 75-80% of the nameplate rating. Still, it would be good to size your charge controller for the full nameplate rating of 1000W (4 x 250w). 1000W / 12 = 83 in a 100% efficient controller. Even with a high efficiency controller you wont see more than 80A, so an MPPT charge controller rated 80A or higher should be fine.

Wow! I really appreciate the quick response! I have to find a good charge controller 80a or higher. Any suggestions? There are so many on the market that makes it difficult to choose. Thank you so much!

 

[el-guapin]

Hello everyone! I am new to this forum and I already have a solar power system ............

Welcome!

 

[Horsefly]

Wow! I really appreciate the quick response! I have to find a good charge controller 80a or higher. Any suggestions? There are so many on the market that makes it difficult to choose. Thank you so much!

Off topic note: I really thought a bunch of the regulars would respond to this thread instead of me, but....

So I'm a bit uninformed, as I haven't been in the market for a few years (maybe 5). "Back in the day" (boy do I sound old) names like Outback, Midnite, and Morningstar were names you could count on. My guess is that those names are still good, but there are others that are good, even if I don't know much about them. I hear lots of horror stories here and elsewhere about people buying unheard-of brands from somewhere on the Internet. Not saying you can't find good things on the Internet, but it is a bit like gambling in Vegas: The house wins most of the time.

Keep in mind that there are two key specs on a Solar Charge Controller: Voltage, and Amperage. The voltage is a limit on the input voltage. You CAN NOT exceed that. So you need to take the open circuit voltage of the panels you are connecting, however they are being connected, and no matter what happens you can't exceed that limit. People often forget about the fact that in cold temperatures panels can have a much larger open circuit voltage right before they produce current, and that can burn up a charge controller. The second spec is the Amps. This is a maximum that the controller will put out, but it won't harm the controller is provided more power than it can put out. So in your example, if you bought a charge controller that only was rated to 60A, it would probably be OK. It wouldn't hurt the charge controller that you were putting in enough power to get 80A out. The charge controller would limit it. On the other hand, if you wire up your panels to the charge controller so that you exceeded the max voltage in (remember, use the Voc - open circuit voltage) you will destroy the charge controller.

I'm hesitant to mention particular models of SCC for you to go look at, but I'm hopeful that others will weigh in here.

 

[Hedges]

Victron is supposed to be good. Epever is economical, but I've read a few issues on this forum.

Charge Controllers | SanTan Solar

store.santansolar.com

Midnight classic is said to be good. They have other models too. Search the forum for them.

Category Products - MidNite Solar's

MidNite Solar Category Products.

www.midnitesolar.com

 

[Horsefly]

Hello everyone! I am new to this forum and I already have a solar power system for my cabin but I want to add some panels to it. I am not sure where I should ask the questions I have. I would appreciate any help to guide me in the right direction.
thanks

By the way: The next time you start a thread, I'd suggest you name it with something more descriptive, like (in this case): "Need help on expanding solar". I think you didn't get as many responses as I would expect mainly because not that many people decided to look at a thread titled "Hello".

Not a big deal, but something for next time.

 

[Steve_S]

Welcome to the Forum Pepite.
There are a few of us "Geezers" who are running Midnite & Other Tier-1 products as well as other goodies. I myself am a Rural / Remote Off gridder and have been on the trail a wee while ;-). Started with Heavy Lead and now LFP & Lead.

The world of Solar and all related tech has changed HUGELY in the past 5 years, Costs have as well (dropped \\YAY// ). Now I would ask you to SLOW Down as I read the excitement in your writing... Rule 1, Develop a Plan & STICK TO IT... You can get a Huge Amount of info from this forum and it is very easy to become overloaded / overwhelmed.

And now a Tad bit of Clarity to simplify your life.
You are coming from a LEAD world, "Brute Force Tech" and talking to Lithium Folks here so things can be muddled. Several terms are used for battery tech BUT context is not the same... IE: Lithium Folks refer to SOC (State of Charge) as opposed to DOD (Depth of Discharge), C-Rate is also looked at differently. Any Lithium Based tech is NOT Brute Force it is in fact Millivolt Sensitive (many don't realize that, well till later after wasted $$). So BE CAREFUL with Terms relative to Context & Tech, some are not interchangeable.

A few differences also to understand... Lead being brute force tech takes a lot of abuses and while it works and has done so for a long time, FLA is not that efficient and on average is 75% (Deep Cycle Heavy Lead can be up to 85%) while LFP (LiFePo4) and other Lithium is 99% Efficient. This makes Charging a lot better of course. Lead can ONLY go to 50% DOD while LFP can do 100% DOD (Most every stops at 10-15% SOC).

Once you know how big your battery is to be then you will know how much it needs to be charged and then you look at the charge sources (Solar Charge Controller, Inverter/Charger) to be able to support that need. Then you have to figure out what & how much solar panel is required to support that charging. A big battery that you cannot charge won't help you much.

In 2021, we now have many good quality AIO's (All In Ones) available from reputable manufacturers. Budget will of course affect what you buy but for "Value" MPP-Solar is good, for mid-upper grade Growatt and for Hi End look towards Victron.

usamppsolar – Solar Made Easy!

usamppsolar.com

Growatt

Victron Energy

Victron Energy - the professional choice for independent electric power

www.victronenergy.com

For the best answers to your questions I suggest the following.
* Tell us your "General Location" nearest large city.
* Do you have clear access to Sun or only at specific times of day ?
- Do you have a situation where you can get good sun in Morning & Afternoon from different locations. (Roof that runs North-South for example, so Morning Sun on E Side & Afternoon Sun on W Side.) * This is where Dual SCC' really Shine. (pun intended LOL)
* Description of your current system setup.
* Amount of usage you expect in kWh per day.
* Amount of Battery Reserve you wish.
* External/Supplemental Charging options wanted ? IE: Do you want to have an Auto-Gen-Start or manually run a Genset to charge or ?

Some Tidbits, as you asked about an 80A Charger. Assuming you are staying 12V.
12V/280AH/3,584Wh battery pack can discharge @ 1C-Rate 280A for One Hour, and it can take 0.5C-Rate 140A Charge for Two Hours.
Optimal Charge rate for reduced stress and for longevity (and thermal control) is recommended at 0.25C or 70A.
Packs in Parallel will divide & share load proportionately. If properly configured a single pack can act as Last Man Standing for Fault Tolerance.

Solar Panels are NOT ALL EQUAL !
Obviously Mono-Facial and Bi-Facial are different and most often Bi-Facial is useless without the proper "environment" for them ie Spectrum Reflective Background at an appropriate distance). But there are more alphabet soup versions (names) than anyone can track. Some are better in shady areas than others and they have various attributes. This is a Good AT A GLANCE guide to the different panel types & their Pros/Cons. https://www.aurorasolar.com/blog/solar-panel-types-guide/ *FYI: Typically panels rated above 330W-350W are Bi-Facial, pay attention to the details. There are some Mono Panels up to 450W BUT these are Large Format Panels (greater than the normal 72-cell panels)

Hope some of this info is helpful.
Take your time, ask lots of questions and be especially certain NOT to mix up terminologies (it can be quite frustrating for everyone), come up with a plan and then Vette it before buying a single solitary gadget.