[wadedog]

I would like to figure out how to use a solar cell to run a fridge and a tv.

How big of a cell do i need and whats the best way to go about it.

should i get like a 15 watt cell and use it to charge a deep cycle battery and a power inverter of some size .

I'm not sure how well cells charge in good sun and low light conditions to know if the battery would stay charged and be able to run the items I want.

Anyone done this that can help me?

 

[Straight Razor]

The small handheld TV run on five 1.5 volt batteries. Two 4.5 volt solar cells ($10) in series should run one.

 

[wadedog]

And with next year not being able to use a tv with a antenna I don't think that will help much.

How much power does it take to charge a battery to run a inverter for a small bar type fridge ?

Is that possible without spending mega bucks for solar cells.

 

[joebob1112003]

My goal is to buy several batteries, at least a 65 watt solar panel and a 2500 to 3000 watt inverter. I have a smaller setup. I have a 5 watt solar panel, a 300 and 500 watt inverter and a trolling battery, I plan to use the smaller unit to power tv's and lights etc. I figure the larger setup will cost me around $700.00-$800.00 but I can run a small microwave and small refrigerator. I also plan on building one of those lawnmower/ car altenator chargers but I can just crank up my truck to recharge low batteries.

 

[ijuswannalive]

I do not fully understand the charging thing.

If I have a 60 watt solar panel plugged into a deep cycle battery and a power inverter plugged into that, will that 60 watt panel be enough to run a power device 24 hours a day

 

[joebob1112003]

Charging

I'm still learning about all of this. My 5 watt solar panel will charge one battery enough for night use. Small stuff. For bigger appliances, just put a few batteries in a series and let the 65 watt panel charge them and have a 2500 to 3000 watt inverter. At night when the current falls off, use a generator or your vehicle to recharge. I don't want to depend on gasoline. As soon as I find a fix for that my I will be self sufficiant.

 

[joebob1112003]

Inverters

My cousin is a truck driver and depends on his 2500 watt inverter to run his apartment size refrig. and microwave. He has told me that the only problem he has had was trying to use his coffee pot. I know the truck runs all the time so recharging the batteries is not a problem. For those that can afford it, the highest wattage panels and the biggest inverter will make your life great. Just be sure to buy plenty of batteries. At night the batteries will haft to be changed to keep up unless you have a way to recharge during night time.

 

[Herne]

Inverters not needed.

I will apologise upfront for a long-winded post. I do know how this stuff works and would like to help, so bear with me :

IMHO inverters are still generally less cost-efficient and not the way to go. I have been totally solar for several years and still see no need to get an inverter. My batteries have lasted much longer than friends who went the inverter route.

There are plenty of very efficient 12VDC/24VDC compressor fridges out there. You can even build your own insulated fridge-freezer 'box' and fit one of these to it; this is how it's done on boats! Google them for US sources.

Products - Danfoss

See here for application notes and technical info:

Products - Danfoss Technical select Direct Current Compressors link, and see the Literature tab.

I have a 240 litre Waeco fridge-freezer (using a Danfoss BD50F compressor) that auto senses the voltage source it is connected to and switches to the 'dominant' source automatically. Eg. normal mode of operation is 12VDC from solar panels. From time to time I give them a rest and manually switch to my BOV's 24VDC 'start batteries' while driving.

If I am somewhere with mains power (240VAC), plugging the lead in causes the fridge to switch to mains. Also, if I start the generator, it also kicks over to 240VAC. This setup requires a small relatively inexpensive add on sensor and rectifier box from Mobitronics ( https://www.compass24.com/watersports/abnetshop.pl?nummernliste=563595 ) to rectify the applied mains voltage source.

This might sound complicated , but it's not at all! It's also more efficient than using an inverter. I would only use an inverter if there was no option but to have a mains powered appliance, because they will shorten your battery life as well.

Things that make a difference to your solar setup: the current (Amps) your fridge draws at startup, and when running; The number of times per day your fridge compressor cuts in; the length of time it runs when it cuts in; your batteries (number, voltage, configuration); panels (number and wattage); hours of direct sunlight per day; Solar charge controller etc. These all need to be worked out. Luckily there are on-line tools and calculators to help:

This company has some examples of load calculation sheets etc

http://www.rpc.com.au/products/services/examples.html

Where to start: Read everything you can lay your hands on about solar. Here's the location for best books I've found so far. Collyn Rivers is an Engineer with many many years experience. Truly you can't go wrong with these books.

http://www.caravanandmotorhomebooks.com/

Here's a review of solar system buying on ebay:

eBay Australia Guides - Buying solar panels and alternative energy on eBay

Work out which fridge you will use (110VAC + inverter or 12/24VDC). Work out what the 'power debt' is that your batteries and solar system will have to supply (and recharge daily).

Remember that fridges draw more current on startup (for approx. 30 secs) then settle down to a lesser draw. Your battery system and charging system must be able to cope with this. For example, my fridge draws 9.0A at startup and drops back to about 4A running.

Here's a review of Inverter + mains power fridge versus 12VDC fridge. Remember the DC fridge is more expensive to buy, but you can convert a mains fridge to 12VDC at a lesser cost. Don't worry about the Motorhome references, just read 'BOL' instead.

READ the next link, if nothing else!
http://www.fridge-and-solar.net/fridgetest1.htm

See also: http://www.fridge-and-solar.net/info.htm

My Waeco fridge uses a 12VDC / 24VDC Danfoss BD50F compressor. There is also a lesser power BD35F model. Here's the beauty of it - you can buy the compressors separately and convert your existing 110 VAC / 240VAC fridge-freezer.

Many marine installations use these compressors because they suit custom-made fridge applications. Here's a couple of links to get you started. Also, all Waeco mini-fridges for camping / vehicles use these compressors as well.

http://www.technologydiamonds.com/d...or_Components/compressors/Danfoss/danfoss.htm

http://www.ra.danfoss.com/Technical...Article/author_1/RAC Compressors Oct 2005.pdf

It is also more efficient to run off 24VDC than 12VDC (Ohms Law > P=iv, twice the voltage means half the current draw), so you might even consider having a totally 24 Volt system. But a lot of solar systems are geared to 12VDC operation. A 24V system will likely cost significantly more to setup.

Please don't let all this scare you off. Let me know if I can help in any way. Good Luck with it, Herne :

P.S. My solar system is as follows: 2 x 80Watt BP Unisolar amorphous silicon panels, a BP Solar PL-20 Regulator, 4 x Trojan T105 Deep Cycle Battery 6V 225Ah (wired in series-parallel to give 12 VDC output).

 

[joebob1112003]

I just was giving the best advice that I know. You seem to have figured it out. Thank you.

 

[FlungPup]

Check out the magazine Home Power. It's all about renewable energy systems and quite good.