Application for 100W panel

[solardreamer]

It wouldn't be a problem for the motor because as the voltage rises, current flows through the motor and the panel can't rise to open-circuit voltage. A solar regulator is different because there are times where the controller could open the charge circuit and let the panel rise close to Voc.

The panel voltage may not be able to rise to Voc but it can still rise too high for the motor. I found out the hard way when I tried to use 50W panel Voc~20Vwith a 20W 12V fan that was supposed to handle up to 18V but because the motor does not draw enough current during particularly sunny days to pull down the panel voltage enough and burned out. Twice. I finally realized what was happening when I caught the panel voltage going above 19V under load and immediately disconnected the fan before it burned out again.

[bcroe]

It wouldn't be a problem for the motor because as the voltage rises, current flows through the motor and the panel can't rise to open-circuit voltage. A solar regulator is different because there are times where the controller could open the charge circuit and let the panel rise close to Voc.

If you use a 100W panel on a 10W motor, at times it is necessary. The big panel will keep the motor running more hours and
over more weather. Bruce Roe

[solardreamer]

If the panel open circuit voltage is at or below the motor maximum input voltage, there will be no problem. Bruce Roe

I agree that's an easy way to check for compatibility. Another way to ensure compatibility is to add auto buck/boost converter the will allow you control the voltage and current to the DC fan. I actually use one to ensure compatibility but also to maintain stable fan speed and noise.

[sdold]

If the panel open circuit voltage is at or below the motor maximum input voltage, there will be no problem. Bruce Roe

It wouldn't be a problem for the motor because as the voltage rises, current flows through the motor and the panel can't rise to open-circuit voltage. A solar regulator is different because there are times where the controller could open the charge circuit and let the panel rise close to Voc.

[Sunking]

If the panel open circuit voltage is at or below the motor maximum input voltage, there will be no problem. Bruce Roe

Voc is no problem for anything as there is no current.

[SunEagle]

If the panel open circuit voltage is at or below the motor maximum input voltage, there will be no problem. Bruce Roe

I agree. The OP just needs to check first before purchasing a DC fan.

[bcroe]

Using a solar panel directly wired to a fan driven DC motor will work. The problem is making sure the motor can accept the amount of power the panel can put out. As someone stated before the fan can end up spinning very fast and exceed it's limits.

The 100W panel will work but needs to be matched up to the DC load.

I had 2 attic fans that did a great job and they each only had a 10w panel running the motor. I would hate to see what a 100W panel would do to them.

If the panel open circuit voltage is at or below the motor maximum input voltage, there will be no problem. Bruce Roe

[SunEagle]

100W panel should be more than adequate for good size attic fan. Just remember to have thermostat that only turns on the fan only when it's hot enough. Your panel is big enough that you can even add a battery and charge controller for powering the fan after sundown to cool down the attic faster. I have such system with a 50W panel and it definitely helps keep the house cooler.

Using a solar panel directly wired to a fan driven DC motor will work. The problem is making sure the motor can accept the amount of power the panel can put out. As someone stated before the fan can end up spinning very fast and exceed it's limits.

The 100W panel will work but needs to be matched up to the DC load.

I had 2 attic fans that did a great job and they each only had a 10w panel running the motor. I would hate to see what a 100W panel would do to them.

[solardreamer]

I bought a 100W panel and my intended purpose is no longer viable. I am wondering what I can use a 100W panel for at home, without having to spend a bunch of money.

I thought of connecting it directly to a 24V fan in the attic (panel on roof) to vent the hot air during summer sunlight hours.

I thought of connecting it to nicrom (sp) wire heater rewound or custom built for the expected voltage/current to warm the house during winter sunlight hours.

That's all I could think of. Otherwise, the panel is just in the way and causing consternation.

100W panel should be more than adequate for good size attic fan. Just remember to have thermostat that only turns on the fan only when it's hot enough. Your panel is big enough that you can even add a battery and charge controller for powering the fan after sundown to cool down the attic faster. I have such system with a 50W panel and it definitely helps keep the house cooler.

[SunEagle]

What is meant by wearing the panel down? Do they wear out like batteries, meaning they age the same if in use and also if in storage? I kinda thought they were more like solid state IC's. Last forever other than keeping them clean...

Solar pv cells will slowly degrade the more they are exposed to sunlight and heat. So sometimes it is better to store the panels then to just put them up and try to get something out of them.

Now batteries are a different story. They will die if they are being used or stored. You can't keep them alive forever or at least not for 25 years like a solar panel.

[ctwo]

What is meant by wearing the panel down? Do they wear out like batteries, meaning they age the same if in use and also if in storage? I kinda thought they were more like solid state IC's. Last forever other than keeping them clean...

[LETitROLL]

I bought a 100W panel and my intended purpose is no longer viable. I am wondering what I can use a 100W panel for at home, without having to spend a bunch of money.

I thought of connecting it directly to a 24V fan in the attic (panel on roof) to vent the hot air during summer sunlight hours.

I thought of connecting it to nicrom (sp) wire heater rewound or custom built for the expected voltage/current to warm the house during winter sunlight hours.

That's all I could think of. Otherwise, the panel is just in the way and causing consternation.

Attic fans work okay, if you get a good match, need them most in summer when sun hours are longer, best to have a buck converter if you are thinking of wiring it direct, they are only a few dollars for a cheap one.

Very bad math on trying to do any kind of heating with a single 100w panel, unless it is just a cup of coffee, or 1 cubic foot of air, fixed heat element loads can only be optimized for a certain current flow, problem is with solar panels the current varies dramatically throughout the day, so you just have to average or pick a point where you think it will spend more time in that zone, and the fall off in power is squared when you are not optimized, so it is impossible to get anywhere near your panels rated output for any length of time. You can expect about 1 penny a day in generated power towards heat loads, maybe 2 cents if your in a very sunny winter place, not worth wearing the panel out for that, better to have it in storage and ready to go if you ever really need it for a grid down situation or??

[bcroe]

DC motors have a lot of tolerance for power variations, they just vary the power output. I have varied the voltage over
about a 3:1 range for controlling fans, which don't need a big surge to get started. Bruce Roe

[sdold]

A friend of mine ended up with a 100W panel like that and I told him to get rid of it, that it wasn't worth much at home. Well, against my advice he bought two automotive 12V radiator fans and connected them in series, I think. Lo and behold, when the sun is around mid day, the fans go like hell. He made an attic fan out of it. It was weird how the current draw worked out just about right. If it was me, I'd put in on Craigslist.

[ButchDeal]

What about adding an Enphase or Sunny Boy Micro-Inverter?

Getting a permit and interconnect for a single 100w install?