McDave wrote:@ flboy,
I Still really don't know enough about solar to make an informed decision if it means a substantial investment. I would consider that Ctek unit a less than substantial investment. However, you still need panels and I would want additional battery storage capacity.
'Maybe you can point me in the right direction here Don. I need a fundamental education in solar and systems. Now, I lived in Alb. N.M. and had connections to Sandia Nat.Labs and Los Alamos N.L. as well as my DOD & DOE experience, and watched as this stuff was developed, but that was 2 lifetimes ago and now that it is at consumer level it's a completely different animal. I doubt if they even use Flux Capacitors anymore, so I'm pretty far out of the game. What I need is a trusted source of basic info so I can put pure, clean data in there to start with. Once I have the basics I can do the research and homework needed to make a good decision, in theory. So, any ideas? Please don't say "Solar for Dummies". My wife always says that. Funny every time...
Thanks in advance,
McDave
I think you already know what you need to know. Knowledge of the physics of Photovoltaic Solar Panels is not needed although interesting. Basically all you need is Ohms law, basic DC wiring skills (polarity, wire gage, ampacity), and knowing the storage capacity in Amp hours needed to meet your needs in a day (only 50% of aH is available for repeated use on deep cycle battery). Based on your reefer explanations... you understand how to figure that out.
From there, I use a rule of thumb of 1Watt of panel for each Ah of battery (even though you only use max 50% of available aH) .... that get's you in the ballpark, but average daily sunlight, and many other environmental variables may require tweaks (in my case I am @ ~1.4W to 1aH because camping is usually partial sunlight and I like a quicker charge/capacity to recover from a rapid discharge if I choose to run the AC off the inverter for a few hours).. Just leave room to add another panel if you find the rule of thumb leaves you short of a full replenishment each day during the daylight hours. Not a problem per se if you end up with more panel than battery capacity and usage...usually not the case. On the short end, you can always supplement with the Tow Vehicle or Gen in a pinch if you don't have room or desire for the extra panel. Always good to have a backup source in any case. Solar is not always there for you due to environment and day/night.... a generator is always ready. Bottom line take away... battery capacity is more important than solar capacity and an easy calculation... error on the side of the battery and supplement the solar charge until you can expand the array if it can't keep up with your demand).
Sparing the physics, remember monocrystalline is marginally better (more efficient) than polycrystalline and usually a little more expensive for that reason (more pure silicon).. . The Amorphous (thin film) is still relatively new and a lighter technology which is cheaper to manufacture and can used more on flexible surfaces. It is yet to prove itself in harsh conditions over a long periods of time whereas the other two are proven technology... that being the case, I am not willing to pay for it (even though a little cheaper) nor care to test it (maybe if I ever build a electric powered fixed wing UAV :-) ) . Typically for monocrystalline panels, you should expect to pay somewhere between $1.25 to $1.50 per watt for a panel. Less if you are patient for a good deal.
Sounds like you already know the difference and trade offs with a PWM vs MPPT controller and that's why MPPT controllers cost more. Choose a controller size that gives some margin for expansion room if you decide to get another panel. Determine minimum controller size by solving for amps knowing panel watts and given 12vdc (I = P/E). Example, when I had 4 100W panels , if I had a 30A charger, I'd have needed to replace with the 40A when I added the fifth panel. Also in full sun and efficiency, I'd have been running it very close to it's theoretical limit (not good, but typically would rarely happen for many reasons).
There you go... you got it, but then again, I think you already had it... maybe giving me a test
.
A free tip for solar dependency... plan most of your heavy power usage for early in the day if possible so you have plenty of daylight to recover the batteries.. Lowest usage should be after dark .
