100 watt panels or 250 watt? Trying to figure it out, I need your help, please.

Hello,

Yeah, it's been a very long time since I posted something, but here I am again.  Here I am watching tons of videos and other things on living off grid and preparing to build a homestead.  I have a little cash for some solar panels and I was just wondering before I chose a kit like this one here https://www.amazon.com/Renogy-Monocrystalline-Starter-Charge-Controller/dp/B06X1FV5N2

I have two questions really, one is monocrystalline or polycrystalline?  
And two, if I want a system I can expand should I get 100 watt panels or something with more wattage?  I guess my question is also what kind of solar panels are there most of out there?

Thanks for all your help

Mono and Poly doesn't really make a big difference. Mono is technically worse but they are more flexible so it might be worth the tradeoff.  I would go with a 250W or 320W system so that you can upgrade your system going forward.

An off-grid setup will require quite a few components.
Solar Panel (250W-320W/panel @ $1/W)
Charger/Controller (https://www.wholesalesolar.com/charge-controllers)
Battery
Inverter
Backup Generator(optional)
Appliances (this is whole point for the system)
Railing
Wires
Shutoff
Lighting arrestors
Breaker/Combiner Box

Here is a sample setup
4x 250W solar panels = 1000W * 4hrs/day = 4kWHr/day ($1000)
1x 4,000W Charge Controller = ($600) manage 1-16 solar panels (250W-4,000W)
2x 4kWHr Battery = ($1200) with a 50% depth of discharge aka 5yr life.
1x 4,000W Inverter = ($1200) usually about $0.50/W
Total = $4,000

Greg Canicio wrote:what kind of solar panels are there most of out there?

I believe the only significant difference between solar panels which needs consideration is their voltage at the terminals. I believe the most common are rated at 18V.

If you are building a 12V system for car battery storage, you would normally use 18V panels. This is because when you place a load across a solar panel (or any power supply), its voltage drops. 18V panels end up being just about right for charging a 12V battery.

If you want to create an array of panels, they all need to be the same voltage. Of course, you will always need a battery management system.

I'm not an expert on this subject so you probably want to get confirmation of what I've said here.

Yes, watts and voltage. You can probably get 300 watt panels for the same price as 100 watt range ones.

Monocrystaline panels are proven to last 50 years at 90% or better of their original output. Monocrystaline panels also have higher voltage at higher module temps. This matters, especially in 12v systems with minimum size wire and longer distance.

I would carefully compare online kits to simply selecting a panel(s) and a controller yourself. I find most kits lacking and components in them lower grade or less desirable.

300 watt solarworlds are $179 apiece right now..... not for long. I specify solarworld on all of my desig s and installs. No other manufacturer has the long term data to back up reliability and they are also assembled way nicer on examination.

I think before starting a system that you might want to add on to some day, it's a good idea to think about the amount of solar panels you'd like to have later on, and then to choose the voltage of your system based on that.

12v panels give a higher amount of amp hours (amp hours = watts divided by volts), so a bigger (and more expensive) charge controller is needed than is needed for 24v when you want to upgrade. Also, it's much easier to find panels for 24v systems than it is 12v, as 24v seems to be the standard these days.

Thank you everyone for your responses.  Yeah it seems I would need more planing for sure.   Now what's the difference between 12v and 24v if I'm going to convert it to 110v anyhow?  

S Bengi wrote:Mono and Poly doesn't really make a big difference. Mono is technically worse but they are more flexible so it might be worth the tradeoff.

Mono is hands down better then poly in every way conceivable!  Have your tried both? There really is no comparison!

Greg Canicio wrote:Thank you everyone for your responses.  Yeah it seems I would need more planing for sure.   Now what's the difference between 12v and 24v if I'm going to convert it to 110v anyhow?  

It does not matter as long as it is in range to allow power electronics to make sure the system is happy.

More 60 cell (20v) modules are likely in the field at this point. Dont get hung up on 12v panels or 24v panels, for the most part, these are not what is used at all aside from pwm micro systems or using whatever is available to you. Some pwm controllers actually have high acceptance voltages. Some schneider/Trace/zantrex c series pwms can accept 125v and work fine, they just will not seek mpp.

Your control will require higher than max absorb voltage to operate effectively.

As far as 12v or 24v batteries, the higher the load amps are, higher battery voltages will allow more power per amp and thus lower current capacities in everything connected to it for the same power transmission.

For cabins, conserving homes and small standalone systems 12v and 24v can work nicely. In higher power systems 48v or higher is desirable. If you require more than 2000-2500w , more than occasionally, 48v will be a blessing when funding, installing and living with the system.