Compact solar genny

[freshair]

Hello Board,

 Been reading the board for a few months, very interesting stuff here. In a few months I plan on experimenting with a small mill (I think I'd have trouble with anything large here).

I was recently presented with a project to supply electric for an upcoming event. In the past we had access to grid power most of the time, but now we are in need of an alternate source. The total "nameplate" amp draw for the equipment is 3.35 amps. There is one additional item I have always used, a 500va UPS. This item is rated 500va, 300watts, and the "nameplate" states 10 amps (not sure what version of Ohm's law they used to figure this all out LOL). The UPS is the only item I have tested, and by its self with a dead battery it was drawing .1amps. So it looks like my total load is 3.45 amps (but I really don't think its that much).

What I would like to do is put together a compact solar/battery source. I don't think I can put this together cheaper than a gas genny so its not about cost, but the cost of gas, oil, to have to carry gas, and the last thing noise of the genny. As stated above I plan on putting up a mill so parts wouldn't go to waste if this didn't workout (batteries, inverter). I have some ideas of what I want but not really sure about the solar.

So my question to the board is, do you think this is possible? Keep in mind this will have to be compact and be able to be broken down at the end of day. Any comment or help is welcome.

Thanks

       freshair  

[ghurd]

There really isn't enough information.

The 3.35 / 3.45A draw has me more than a little confused. AC? DC? Volts?

Kind of sounds like a combination of AC and DC. Not sure where the 0.1A comes from.

What is it? Cash register using the peak amps only when banging out a receipt a very small percentage of the time, or maybe a light bulb using the peak amps 100% of the time.

Was 'it' run from the 300W UPS before?

Many smaller UPS are quite inefficient. The system may do a lot better with a 400~500W inverter, and a spare inverter just in case.

How long will the system be remote? A day? A week?

Compact? To fit in a 16' box truck or a Toyota station wagon?

It may not even need charged, or need much charging.

G-

[freshair]

Hello ghrud,

 Thanks for the reply. This all came up on me quick (end of last week) and I thought things were happening this weekend so I had scrapped the idea. Then I found out it was the weekend of the 6th/7th so I made this post.

The amp's I posted are a total of the "name plate" AC amp's of all the equipment (Laptop, printer, PA, etc.) The system worked fine through the 500va APC UPS and never had a problem "on grid". What I have done now is make up a cord that I have access to the "hot" so I can check amp draw. The .1amps is what the UPS draws "stand alone" but the battery was dead so it was charging (hadden't been used in a while). Most of the items are low voltage and have a "power pack". Two of the items use the same type "pack" and are rated .5 amps each. I have pluged one into the UPS (after the battery was charged) and I still get .1amps (and it was under load "again something charging") I haven't had the chance to add everything yet, but this confirms me saying "I really don't think it draws 3.45amps". Another item that is rated .5 amps is the printer but that won't be used often. As for the time it will be set up about 9:00am and broken down about 6:00pm. Most times it will be one day but this time will be two (I can top off the batteries over night). other times it should be able to charge its self.

Being a little pressed for time I started ordering some items. figured I would go for it.

INVERTER = We are on the same page here (I had already ordered two before I saw your post). I got 750watt ones (wanted to go larger in case this didn't work and as my first post), but was concerned about the inverters AMP draw (this is another item I would like to know what version of Ohm's law the use LOL)

BATTERIES = 2 maxx DC from wally world

SOLAR PANELS = 2 from Northern (wanted to do it with one but didn't think it would be enough), still unsure???

This will all be on a cart about the size of the batteries with the removable (adjustable) panels on top.

I'm just not sure the solar will keep up

 Anything you want to add fire away.

Thanks again for the reply

[ghurd]

Sounds like it will work fine.

Some stuff uses quite a bit of power when idle, other stuff does not.

Probably shut off the PA, but let the laptop run... if you know what I mean.

Couple hints. The batteries will last for years, even being fairly deep cycled sometimes, but use a smart charger on them as soon as you get home.

Panels work a LOT better in a situation like that if you can keep them aimed at the sun through the day, so turn the cart several times a day if possible.

If day #1, 6:00, the batteries read less than 12.4V, it would be a good idea to take them to the grid for a charge. Make sure they are 100% charged before day #1, and in the off season.

Don't connect an inverter backwards (don't laugh, you'll see!).  Extra fuses are a good idea.

[freshair]

The laptop HAS to stay on the whole time. From the time we set up its used for registration then it runs the program. Not sure which one will be used (both Dells) one is claimed to run a half a day on its own power. I don't think mine will run an hour on its own. The PA is on most of the time for announcing and during down time music (but not full blast). This is an item that I thought would be consuming a lot of power but thats "name plate" rated .35 amps. (lowest amount of all) I'm sure increased volume would hurt, but I think we will be drawing less. I am leery of the inverter so and am going to still use the UPS. I've had a little experiance with them on company trucks. Not sure of the brand (trucks come with them installed), but one of them burns up the circuit board in Milwaukee power tools (not chargers but the actual tool). Hoping the UPS adds a little protection.

The cart is on large casters so moving it shouldn't be a problem. One end of the panel will be fixed and the other end will be able to raise and lower. When its together I'll take some picks.    

[Spelljammer]

The UPS is a modified sine wave just like the inverter.  Modified sine wave works for about 90% of the stuff, but anytime I charge a tool or cell phone, I use pure sine wave or I just hook directly to the battery (cigarette lighter for cell phone is a good example).

So, if that power tool was messed up on an inverter, it will also mess up on a UPS (assuming you are running off battery and NOT on the grid).  But running laptops, computers, monitors all work fine on a modified sine wave with the exception of a hum in the speakers and monitor sometimes.

Also, your PA may have a hum or buzz, so test it first.  It has to do with how good the filter circuit is inside the power supply of the device.  If it buzzes on the UPS it will buzz on the inverter.  Unless you buy a pure sine wave inverter or use a 12v PA system.

[freshair]

True, I knew that about the UPS and the inverter. I was just hoping APC put a little more into there unit, I've read some horror stories about inverters. "Shouldn't" be any power tools plugged into this system, but you never know. Just like that truck, you realize it when its to late.

Now that I think about it I never had the PA plugged into the UPS before, just a surge strip.

I've looked into the pure sine wave inverters when I started looking into a mill. Big $$$$, they would blow this project out of the water!

Part of the plan is to put a cigarette lighter on this. (another way to run the laptop if necessary). That item can't go down!