A guest post by Michael C
[This is an entry in our non-fiction writing contest where you could win - First Prize a 10 Person Deluxe Family Survival Kit, Second Prize an Herb Seed Bank or Third Prize a copy of Dirt Cheap Survival Retreat. For complete rules and list of prizes see this post.]
Most folks have the “idea” that solar costs lots of big bucks. But the truth of the matter is – solar energy is an investment. Like big power company’s that buy a nuclear power plant. There is a big (one time) up front investment for the company that will usually pay off later.
You would do the same thing – invest in a pile of components that will become your personal utility. The cost of taking care of your utility is minimal – after the initial purchase. You don’t have any monthly bills – it is YOUR utility. Why is solar worth having? Because, it gives you power. The power comes from the sun and goes into your pocket – if you got it. Solar power is nice and quiet – use a night-light to go to the bathroom.
A few people can tell you how to build a solar energy system. But, going into wire sizes, battery sizes, panel sizes and everything else is sure to confuse you to the point of “puttin’ it off”. So, I am going to just describe systems that I made. I am going to describe 3 different sized systems – that you can copy – for your own use. You should copy – but, keep in mind that you can adapt your system to the materials you have. If you have a 100 Watt panel lying around – use it – instead of the 80W panel I used in my medium system.
A small system for me is just some thin-film panels, taped to a piece of stretch proof plastic sheet (from the post office plastic mailer) with wires soldered on. Most productive for recharging batteries or powering a small device. A common connector is style “M” which can be found at Radio Shack.
I added diodes (…N1001) to each solar panel (since they are all in parallel) to block all reverse current – I did not want any panel to “leak” power backwards. At this size of alternate energy system – most of your connections would be soldered. The cost for each thin-film sheet was about $17 (USD) and the wire was cheap speaker wire (24 gage).
The solar panels can be soldered together in parallel, series or both for the voltage/amperage needed. (The thin-film panels can be bought in various sizes too.) At about 12 volts you might consider a 12V solar panel to avoid all the soldering. Thin film panels work great in this case because they are very light weight and portable. You could have these in your BOB, GHB or with your GPS.
This alternate energy system is larger, uses regular components like a framed solar panel. This system is still portable – if you have an electric chain saw, you can roll into the woods and use it. I use a $30 (USD) hand truck from Harbor Freight to “mount” the parts.
The parts consist of 80W solar panel, Xantrex C30 charge controller, 2 – 6 Volt 225 Amp hour batteries, 2 – inverters (400 & 1200 Watt), desulphator and a 12V car outlet. The batteries are inside the wood box, the inverters, desulphator and outlet are on top.
The components for this system can be separated – the battery box is strapped to the hand truck and the solar panel is mounted on the handle with 2 U-clamps. Mounting the panel this way allows me to “swing” the panel up into the sun, I use a stick to keep it there. I used a short extension cord (cut in two) to connect the panel to the battery so I can “unplug” the panel.
Connections from battery to charge controller (and from solar panel to charge controller) are fused using common automotive blade style fuses. The inverters and power outlet have their own (blade style) fusing. The battery and solar panel are the biggest cost in this system. The cost for the panel was $400 (at the time) and the batteries were $150 each.
This system does have 120V AC output but, if you’ll notice – you’re not going to touch it, at all. All components that you handle are only 12 volts, the inverter will be connected to the battery with the cables that they give you.
This system has an 80 Watt solar panel so the output is 80 Watts per hour or 80 Whrs. In a 10 hour sunny day you would get 800 Whrs – enough for 5 – 24W CFL’s for over 6 hours. (This system is bigger then MD’ Creekmore’s system.)
The large solar power setup is just like you see in magazines with solar panels on the roof, a wall full of components and kids playing in the yard. I have 3 – 90W and 6 – 80W (total 750W) solar panels on top and a Solar Boost 50 (charge control), Prosine 2 (2 kW inverter), Xantrex breaker box, Link 10 battery meter (fuel gage), 8 – Trojan L16 batteries (20 kW storage). All components except batteries and panels are mounted on 3/4″ plywood. This means that I have 3 major connections: solar panels, batteries and AC output from the board.
This type of system is best bought as a kit – I bought the first 3 panels with inverter and added the other solar panels and charge controller later. You get almost all the pieces – including roof mounting hardware for the solar panels and the right size wires.
The trick with building this system is to put most of the stuff on a plywood board. I set the parts on plywood and arranged it to my liking. The breaker box should be located close to all the other stuff to minimize wire length. I had my panels mounted on the ground for good snow removal but, after thinking about theft (nice shiny blue panels) I mounted them on the roof. I use a snow rake and angle the panels steep (70 degree).
The best feature of this kit was the inverter. The inverter has an automatic transfer switch (the thing that goes click in a UPS when the power goes out) and 3 stage battery charger built-in. It is true sine wave (yes, had it hooked up to my scope meter). I added the breaker box because you just can’t get 300 amp DC rated fuses from the electric store.
I normally use cheap grid power for running everything but, when the power goes out – its solar time. If you have heard neighbors say something like “I have 100 amp service” then this inverter gives you 15 amp service. You can run up to 15 amps at 100% duty, it will surge to 30 amps (4 kW). This inverter is not grid tie but, UPS (uninterruptable Power Supply) tied. I have my fridge on this inverter in case of power outage.
Here is my little lead in on efficiency. My fridge (19 cf. Kenmore side by side) uses 1.12 kW a day, in 2 hours of sun – my panels will generate 1.5 kW – enough to cover my fridge power (and inverter overhead) use for a day. This fridge is 20% more efficient than every other fridge in its class (19-21 cubic foot). It cost $700 (USD) when I bought it. In the years that I have had it (about 8) it paid for itself in lower electric costs. It will always “pay you” to buy a new fridge.
Try to place the panels where they get sunlight, I should say “where they get the most sunlight”. If you have a tree that shades your panels at 2pm – move the panels so that the tree shades them at 6pm. I know that my roof space is limited but, I plan on getting the “best” light (10 am-3 pm) that I can. Losing energy in the winter because the tree shades at 2 pm is very costly (especially after all the money you paid for solar!)
SAFETY for the small system consists of not burning yourself with the soldering iron. The medium system has batteries that could weld your tools to the posts, wrap electrical tape around “good” tools used near the battery, have a tap for the post threads.
The batteries in my medium and large systems are flooded lead acid which means that I have to fill them with pure (distilled) water, I wear rubber gloves for this task and goggles. I also keep the family sized baking soda bucket nearby in case a mouse chews the corner (for water) – lot of solution (more than a gallon) in a 120 pound battery. Lead acid batteries generate hydrogen gas which is explosive, a vented battery box is recommended.
The medium system uses a (cheaper, easer to find) flooded lead acid battery, not the best type (AGM Absorbed Glass Mat or Gel Cell) for this application. Since it could tilt past 40 degrees (max fluid to cap angle) the solution can leak. I installed plastic inside the box to contain any fluid and am aware of this limitation in my system. The box is strapped to the hand truck for quick release to move into a truck bed.
The lead acid batteries that I used were bought before I found out about Edison batteries. Admittedly, the lead acid battery has more power per pound then the Edison (Alkaline based Nickel-Iron) battery but, have become the “throw away” part of every solar power system. Edison batteries will (have) last for a hundred years, don’t sulphate, don’t break down (lead plate flaking) and if they run dry – simply refill. In fact, replacing the alkaline solution would only take Berky water and wood ash (lye is alkaline) solution. Last but not least – no chance for explosion, does not generate hydrogen.
If you have read “31 Days to Survival” then you know that there is a chapter on alternate energy. I think that any of these systems will count for that day. Please share your comments and thoughts in the comments below.