I don't know what's wrong with my brain, but it just can't think in solar. Maybe you can help me with this design?
We need something small, to light some DC lamps (this to start, more later) and have this solar panel which was supposed to have a controller thingy that stopped overcharging of the battery but didn't.
Since we are lighting in the winter, when there is less sun, we were thinking of adding a small tiny wind generator to help trickle charge the battery too.
What I think I need is
some sort of box that takes care of the battery so it won't overcharge or drain through the solar cells or something... this is where my brain goes squishy.
Since what we are plugging into the system is DC, I don't think we need the thingy that changes it to AC.
I'm hoping there's something affordable, maybe something plug and play? It sure would be nice if they made it like a computer - you buy a box, you buy any monitor you like and they all have the same plug, speakers likewise... plug them in, everything goes happy. What do I need to make my system work?
Since the 10w lighting fixture is your primary load, and you may want to do more, we have to first establish how long and how often you will need it to operate. Then add what you think you will also intend to use... expansion.
The pv panel that you indicate will likely produce enough usable power for one hour of light on any sunny day
For your system, a micro system and most systems, the battery is going to have priority on initial sizing of the system and many times will have the lions share of the budget. It is less expensive to get battery sizing set so you will not have to replace it on expansion of the loads or sources.
Many times it will suit to establish a budget and build the system to that, then live within the confines.
Your battery may cost as much as $250 (2× golf car battery with cables and fuse duracell 220ah/$110 ea.) or less (single 80-100ah 12v).
Your charge controller, $20- $200
Some fuses- distribution and wire $25-$100
A serious pv panel, $165-$185 for a canadian solar 275-340 watt. (Compare this at $30-$50 on 5-10 watt panels)
A system like this will control the solar reliably for 20 years or more, produce power for decades longer and you could get 8-12 years from your battery if you care for it well and discharge to a shallow soc at low current levels.
Most wind generators will double this cost or material and ancilliary equipment outlay, even if you get the turbine for $300 or less.
Missouri wind and solar makes a decent gennie kit that people seem to have success with. I hqve installed them. 400w to 1200w is a usable range. hot water/air and other diversions of wind generated power are a good benifit along with charging while sunshine is scarce.
If the system is for occasional lighting only, then the panel you have may be great and the suggestions above are for comparative reference. I have no idea what your total concept is!
A 50ah 12v battery will power that light for about 25 hours to 50% dod, when new. When cold or old, oversizing isnt such a waste in hind-sight.
100ah is a healthy 12v storage size, if you need it and if you can charge it full weekly, at least.
Morningstar controls are high quality, full featured, inexpensive and reliable. (Suresine 300w inverter is a cabin lighting and comms champ with hard wire terminals, *but you dont need it.
I will review some plug and plays... usually toy grade or high cost to utililty ratio. There are very few connections to be made in a dc power system of this size.
Most curious, 8-12 year old children can get it connected the first time with the help of the manual or an experienced tutor. This is not to insult, only to highlight the fact for boosting self confidence to go ahead and terminate a couple wires in the persuit of something that lasts longer and performs better that what hangs on a hook at the harbor freight store.
I think its great that people buy them on one hand and deplore it on the other, since results do not match the cost and people must think solar is unusable rather than the reality of poor equipment being lack-luster and expensive.
Or worse... that they couldnt do it themselves.
I must admit i was excited to get my first harbor freight panels and i had one just like yours (smashed) along with two of the 1.5w red auto battery maintenance panels, (still work), that powered our radio station for years.
I would ask the companies that make offgrid systems for a quote (and the list of parts).
(bimblesolar.com being the first one that popped up in a short search.)
Then you can see if they overcharge you on any component (and possibly post the list here too).
A good solar charge controller will protect the battery from over and undercharge.
For the battery, I would either go for cheap old used lead-acid, or get a good Nickel-Iron battery (which are hard to come by).
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