Featured solar panels: where to buy

[freegander]

i like this guy.

he debunks fake MPPT controllers (of which there are many) and has a fun accent

 

[DrewSTNY]

Have you looked into how to do system sizing?

If not, it's pretty simple. I think it will make more sense if we start at what a 100W panel will produce in a day.

At best, you will make full power for about 4-6 hours a day, and limited power for a couple more. I usually figure on getting about 5 hours on average in the US at least. In places further south, the daily output will go for an hour or two more.

This will give you 500 watts of power from a 100 watt panel per day. That's not a lot of electricity, but it's decent and if you plan well, you can have a good performing system. I don't think you will practically run fridges unless they are really efficient, but you can certainly charge phones and have lights at night.

The other way to think is in amp-hours. For simplicity, let's say you have a 120 watt panel. At 12 volts, this is a 10 amp output. The total output for the day would be 50 amp-hours every 24 hours.
The available power every hour of the day combining both solar and batteries while being able to keep the batteries charged would be about 2 amps draw continuosly. That's enough to charge phones or tablets continuously forever, or until the batteries need to be replaced. It is also enough to run an efficient DC compressor fridge (an Engel FP861 draws 1Amp when running).

Remember, your system has to run all your gear and charge your batteries so that you will have power at night, so if you pull more than what your panels make, your batteries WILL GO DEAD eventually that is. This is assuming that you only use your panels to charge your batteries. If you charge the battery bank when driving, your daily usage can be a lot higher, but you will have to start the vehicle every few days to catch the system up.

If you really want to run a big system, I would try to get a couple of 300 watt panels and four golf cart batteries. That will give you about 225 amp-hours to use from the battery bank and 250 amp-hours out of the panels for a day. This translates into a ~9 amp DC load 24/7 with decent sun.

Try to pay less than $0.80 per watt. I have seen deals here and there for $0.56 per watt. It is interesting that in some countries, you can buy solar panels right in the hardware store. I have not scene any for sale where I live, but there may be some closer to the cities.

Another good source is from highway departments replacing panels on their solar powered road signs.

 

[freegander]

thanks, Drew!

I've been using this site: https://www.renogy.com/calculators to try and calculate my energy needs.

i'm pretty sure i'm going to go with a 100W panel, 5A MPPT/10 PWM charge controller, a 80-100ah deepcycle battery (haven't looked too much into this. i just know they're expensive), and a 300w inverter.

then of course i need to figure out wire gauges and fuses and such. that'll come.

Try to pay less than $0.80 per watt. I have seen deals here and there for $0.56 per watt. It is interesting that in some countries, you can buy solar panels right in the hardware store. I have not scene any for sale where I live, but there may be some closer to the cities.

Another good source is from highway departments replacing panels on their solar powered road signs.

so are you saying i shouldn't pay over $80 for a 100W panel? i have no idea where to find these prices. even on ebay, the cheapest i've found is $110.

how do you contact highway departments?

 

[AnOldHope]

I just ordered 4x 50 amp hour batteries today, should arrive in town 3/27, along with the Avanti superconductor fridge.

Tomorrow I'll set up the 3x 180 watt panels from the Grape kit, 40 amp charge controller, but until the batteries arrive it'll feed one of my 125 ah batteries I'll take from one my 4x 100 arrays, and put the 100 ah I picked up today under that.

I think I severely overpaid for wattage, I buy retail, so I likely paid $1.40/watt at least.

 

[DrewSTNY]

Pretty cool calculator! Takes the guesswork out, just have to remember that sun hours is not daylight hours. That's why I suggested a 5-6 hour time period of good panel output.

A 5A MPPT controller might be a wee bit small for that panel as you will be right on the edge at 18V and full output. Unfortunately, chargers don't daisy chain their inputs, so adding a second charger to the same solar panel won't help. Now if you had 2 50-75W panels and 2 5A MPPT controllers, you can hook them up to one battery. They will fight a little bit, but it's not that bad. I had about 3000W at 72V going into an 80A Midnight Solar charger in the winter and it was fine, but when the sun got up high in the sky in the summer, the panels blew out the charge controller. It's now got a 100 or 120A (I can't remember which) on it and we can put a few more panels on before running out of headroom. The math didn't add up and I thought we would be fine, but the panels put out a little bit more power than was advertised. Also, the open circuit voltage on those panels was almost 100v which was insane.

Canadian Solar I think was one company that had pretty good prices on panels. I paid $0.90/watt in Port au Prince and that was double the price that was quoted from a company out in AZ. I think the problem is that you probably need marine grade which will be a bit higher, but I don't know for sure. I see people putting regular panels right out of the stores on sailboats and going to the Caribbean with them and they don't seem to have a problem.

A quick search yields:

Here's one from ALTe - https://www.altestore.com/store/sol...275-watt-mono-solar-panel-black-frame-p40524/ - $0.65/watt for 275W panel

I tend to do larger system that are hard mounted to buildings, but like I said, I have seen these panels get mounted on sailboats which is probably a bit worse than putting them on a van being that the wind and salt water is murder on everything.

 

[freegander]

I think I severely overpaid for wattage, I buy retail, so I likely paid $1.40/watt at least.

part of the alternative energy bourgeoisie over here...

A 5A MPPT controller might be a wee bit small for that panel as you will be right on the edge at 18V and full output.

how about for a 12v panel? i found one that i like better for $112 + free shipping.

Here's one from ALTe - https://www.altestore.com/store/sol...275-watt-mono-solar-panel-black-frame-p40524/ - $0.65/watt for 275W panel

neat! too bad it's from canada. shipping costs $200, haha.

i've also heard of people buying broken panels and soldering them together. it doesn't seem too difficult. for a while, i was communicating with a guy who works for a solar company in CA who was selling broken panels (some of them the frames were just bent a bit) for pretty cheap. i wasn't sure if it was a scam tho. plus shipping was ridiculous.

 

[AnOldHope]

i've also heard of people buying broken panels and soldering them together. it doesn't seem too difficult. for a while, i was communicating with a guy who works for a solar company in CA who was selling broken panels (some of them the frames were just bent a bit) for pretty cheap. i wasn't sure if it was a scam tho. plus shipping was ridiculous.

We could gang up and attack the NCR at the Helios facility, they have a bunch of salvageable arrays...

 

[DrewSTNY]

Didn't realize shipping was so out of sight. Wow. I have never had them shipped, just bought them at the distributor and picked them up. That's probably why they were $0.90 per watt.

I can't find my notes on the free or really cheap used panels. I would probably start calling or emailing around to paving or big road construction companies in your area to see if they know of any panels getting replaced on highway signage or other solar equipment.

I guess we should start lobbying the hardware stores to start carrying them.

It's really strange comparing different countries. When I was in Port au Prince, you could buy 300+ watt solar panels, 20kw generators, 3600v to 240v pole transformers right in the hardware stores, but you couldn't buy hardly any metal pumping parts for love or money.

 

[freegander]

okay. i think i have my panel, inverter, and charge controller picked out. all for ~$150

where could i find "cheap" batteries? i think i'm looking for around 100amps.

then i need wires, fuses, and one of those tool things AnOldHope mentioned. can anyone think of anything else?

 

[AnOldHope]

okay. i think i have my panel, inverter, and charge controller picked out. all for ~$150

where could i find "cheap" batteries? i think i'm looking for around 100amps.

then i need wires, fuses, and one of those tool things AnOldHope mentioned. can anyone think of anything else?

If you're fingers are strong, you can get away without the tool thing, if it comes to it. I'm lazy and have dainty fingers.

 

[freegander]

ok, i'll go without then

 

[freegander]

can someone tell me what the voltage is for this panel?

i'm looking into wire gauge size and the specs say

Peak Circuit Voltage(Voc):22.82V
Max Power Voltage(Vmp):29.2V

does that mean it's 24V?
the title says 12V...

 

[DrewSTNY]

can someone tell me what the voltage is for this panel?

i'm looking into wire gauge size and the specs say

Peak Circuit Voltage(Voc):22.82V
Max Power Voltage(Vmp):29.2V

does that mean it's 24V?
the title says 12V...

Yes, you are correct.

 

[freegander]

thank you! does that have any affect on the charge controller, battery, and inverter i'm able to use?

also for mounting: do people use z brackets for vans? it is my understanding that a z bracket would mount it flush to the roof, which wouldn't allow airflow which would cause heat to interfere with the efficiency of the panels. is this correct? can i use L brackets?

///alllll the questionssss

 

[DrewSTNY]

thank you! does that have any affect on the charge controller, battery, and inverter i'm able to use?

also for mounting: do people use z brackets for vans? it is my understanding that a z bracket would mount it flush to the roof, which wouldn't allow airflow which would cause heat to interfere with the efficiency of the panels. is this correct? can i use L brackets?

///alllll the questionssss

As long as the equipment you are using is rated for a 24v system, you are good. The batteries will probably float charge at 26+ volts anyway. Your inverter input depends on the battery bank voltage, not the panels, so you'll be fine there.

As far as mounting, getting a little air gap of an inch or two should be good. I would use L brackets if I had them.

 

[freegander]

As long as the equipment you are using is rated for a 24v system, you are good. The batteries will probably float charge at 26+ volts anyway. Your inverter input depends on the battery bank voltage, not the panels, so you'll be fine there.

As far as mounting, getting a little air gap of an inch or two should be good. I would use L brackets if I had them.

GREAT thanks!

i hope to do some sort of write-up on my blog or something when i'm finished. there aren't a lot of good in-depth resources about solar that talk about cost AND all the little things you might need.

traditional solar "kits" are such a misnomer. they don't come with everything you need.

i just ordered all of the main components (even found a battery that ships with prime's 2-day guarantee. i'm skeptical) and it was pretty much $300 even. woooooo.

 

[todd]

link to the blog?

 

[freegander]

link to the blog?

it's in the works

 

[DrewSTNY]

Very cool. Can't wait to see the results!

 

[freegander]

why didn't y'all tell me i needed mc4 connector things? : P

got all my stuff today. i paid a bit extra to get my battery in two days vs. a week, cause i'm hoping to hit the road sometime next week. (if i ever finish this ball joint replacement on my van. ughhh)

are all battery terminal screws the same size? i'm assuming i need to get screws and those terminal hook things to put on the end of wires.

after looking more into z-mounts, it appears that they DO give some space between the panel and the roof of the vehicle...like 22mm? lol

i'm really excited to start tinkering with this controller. it's so tiny!

this panel is beautiful. i hope it works. <3