Solar Energy Advice

[RobbieAG]

I’ve been considering getting a solar setup mainly to have some power if and when the power goes out (and for the coming Apocalypse/societal breakdown ha ha) at home. It could also be useful for camping (though not motorcycle camping obviously). I’d like to be able to run a small refrigerator, a water pump, lights, charge cell phones and laptops, maybe a small TV etc. I found this on the web and wanted to do something similar but bigger. I saw the quote below on the “What did you do today” thread and rather than posting questions on there, I thought it better to open a new thread. I figured camping gear would be the best place for it. Bumblebee, you seem to be the resident expert on this (and lots of other stuff) and the quote below is yours, so I was hoping you could chime in (others welcome too of course). I wasn’t sure how big of a solar power panel I’d need, how many batteries, how big of an inverter, which charge controller to use etc. I could buy a kit, but I think I’d rather piece it together myself to have more options and save money. I was originally thinking of running everything off the inverter. For example, I could pick a small fridge at a yard sale really cheap and it could be used for other purposes. An RV fridge would be much more expensive. Maybe that’s not the best idea? Any help is appreciated.

Dump the entire concept of 120VAC (it's incredibly inefficient on a small scale) and run everything off 12VDC. Fridge, hot water, lights, stove, heat can all be motorhome/camper equipment that is 12VDC/propane. Put a small inverter in for the occasional laptop charging. It's incredibly simple stuff.

Summer months I can run on two deep cell batteries at least 80 days before dropping to 11.0VDC and need to charge for a couple hours. 90lbs of propane typically lasts 120days or more assuming I'm not conserving. 50 gallons of water will last 2 weeks for one person. Winter heating runs the power/propane consumption up quite a bit. I ran the numbers and a single 225W solar panel exceeds my total power consumption by at least a factor of three even in the wintertime - that means I'm plugs out and have zero charging requirements except for bad weather.

[countrygrownup]

I think Solindra has that stuff and I hear you can get a good deal

[Bumblebee]

Keep in mind that my situation is much much different than everyone else who is living in civilization. Most everything I have is 12VDC with minimal stuff. (low power consumption) Most everything you currently have is 120VAC and lots of stuff. (high power consumption) I know what I need and what will work on a small scale such as the motorhome or a little cabin without a lot of power needs. (Definition; little cabin; 200 sq ft low power need building, not 3500-5000 sq ft requiring it's own mid size nuclear power plant to run everything) When I need a lot of power for power tools, microwave, air conditioner or charging batteries, I fire up the generator, do what I need to do then shut down again. When I need to charge my laptop, I run an 800W inverter for an hour off the house batteries.

The first step is to define what your needs actually are. Powering your house off grid? Standby power for when the incoming grid power fails? Camping in a tent? Camper? Fulltime camping or just a couple weekends every other year? Low power drain 12VDC systems or high power drain 120VAC systems? Are you in sunny AZ or overcast and snow covered northern states?

The second step is to determine what your power consumption is. How many watts is your fridge, lights and everything else. Add all those numbers up. Assume everything that is normally used is plugged in and running. To realistically get an estimate of what your actual power needs are, double that number. That doubling generally counters power needs for night and cloudy days and startup power spikes for things like fridge compressors and 5 year old batteries that need to be replaced soon. A RV fridge is more spendy and smaller than a house fridge. Brand new mine is $1,300. It also runs on trivial amps and propane for months on end. (My fridge is 12V 10W plus propane, what is yours?) Think in terms of watts, not kilowatts when considering what you will install.

If you want to run a house, it's very doable. A friend of mine out in AZ is totally off grid. The house is about 1000 sq ft and has four solar panels on the roof. I think they're 225W panels like I'm going to get. The panels go through a charge controller and charge 10 deep cell marine batteries. Half the house is 12VDC for things such as lights, water pump, water heater (12V controller and propane) The rest of the place comes off the batteries through a fairly large inverter. The inverter runs a full size refrigerator, microwave, standard house outlets as needed, tv, computer, etc. The furnace is propane and backed by a fireplace. There is plenty of power there and it's liveable very much like a house on the grid. When something isn't needed though, it is turned off. Chargers are only plugged in when they're charging something. All the big house batteries need to be replaced every 5-8 years depending on conditions.
That is for a fully operational house completely off grid. If you have less stuff you can get away with fewer batteries and fewer panels. When it's overcast for too long, you will need a generator or grid power to keep up with the power useage.

For what I'm doing, I'm looking at $600-700 total to put a single 225W panel, wiring, mounts and charge controller onboard wired into the existing batteries. I'm doing the install myself which is much much cheaper than letting some nutjob do the work - remember that I'm the one on the board that doesn't let anyone else fix anything that belongs to me. I also have room for a second panel if I ever decide I need one. When I build a workshop, it will be nearly identical to the systems on the motorhome including RV fridge/water heater/furnace if I were to install that hardware. I know these systems quite well and trust them even though they're more expensive. That's just me though. YMMV.

A bit of advice: Those dinky little panels on the link you posted or the so called super high tech 5-15W panels at the rv/camping stores are a complete waste of money. They will never keep up with a single marine battery that has anything resembling a regular load on them. Those toy project panels should be considered trickle chargers at best, not primary power supplies. Do your homework and get good hardware even if it's 8 times the price. The money is a one time expense if done right and will pay for itself over time.

[RobbieAG]

For what I'm doing, I'm looking at $600-700 total to put a single 225W panel, wiring, mounts and charge controller onboard wired into the existing batteries.

Which panel and charge controller are you getting? I want to start small but not waste time and money on buying "toys". I'd want to be able to use whatever I buy going forward.

[RobbieAG]

Just a quick update. I went ahead and got a marine battery, battery box, and input plugs that I wired up with a fuse. For now I'll keep it charged with a trickle charger and hopefully get a solar panel in the future. I can use it to charge cell phones and laptops etc. and also use it with my power inverter to plug in a few things in the event of power outage. I know this is minimalist, but it's a start.

[n5tbu]

That is a start!
The output plugs will run alot of items,but the wire is too small for a large inverter,which should go straight to the battery terminals.
A large solar panal can charge that setup for a nice Backup system.
Whole house would require many times this setup.

[RobbieAG]

The output plugs are rated at 15 amps and was purchased at an auto parts store. The fuse was rated at 30, so I dropped it down to a 15 amp fuse. The wiring is 12 gauge so that should handle 30 amps with no problem. My inverter is a small one intended for automotive use. I’ll have to experiment with what I can plug into it, but I’m not expecting anything too big. Going forward, I plan to get more 12 volt gear intended for camping or RV use. That way I won’t be relying on the inverter as much.

[illfacebookyou]

Anyone ever look into hyrdo? http://www.motherearthnews.com/Renewable-Energy/1994-04-01/Living-Off-The-Grid-Part-III-A-New-Era-in-Home-Owner-Hydro.aspx?page=4
Obviously its completely dependent on where you live, but in the right area, coupled with solar, it seems like you could almost generate enough power to sell electric to your neighbors haha.

[Bumblebee]

Obviously its completely dependent on where you live, but in the right area, coupled with solar, it seems like you could almost generate enough power to sell electric to your neighbors haha.

The biggest trick is having running water in enough volume to do any good. Most places don't have it though some remote locations do.

$4000-$6000 for 400W? It's time to ditch the inefficient 120VAC nonsense and go 12VDC then drive that off hydro or solar for way less.

It's all about not being a power hog.