My first venture into solar had me doing hours of research. My main purpose is two fold. First I want a system to use on an RV. Secondly just to satisfy my own curiosity. With a lifetime career in electronics and engineering I am always tinkering. So part of this is self education.
During research I found there are many systems, many components, and many so called experts. I found it difficult to pin anything down as being the "best" or "better" in all those categories.
I could have probably bought a cheap package deal to throw out on a sunny day to charge up my battery? It would either work or not work. That would be the end of my knowledge gain. Not much fun taking that approach.
I don't want to come across as an expert by any means. Closer to the opposite. For the most part this is a search for my own knowledge. I will try to put this information into a non-technical format so that any half handy person might benefit from the info.
My objective/budget is to build my initial system for around $750.00
The initial system is being built to keep my single deep cycle battery topped off and run my 12V 82qt ARB Fridge/Freezer. I want components that I can expand without replacing existing parts as the system grows. Future plans are for more panels, multiple batteries, and a 1000W pure sine Inverter
After much research and consideration I have started gathering components for my system. While I could get by with just a panel and a charger, I intend to maximize how much energy my system will capture and store. Plus do this in the shortest time possible to maximize available sunlight.
Most cheaper chargers, even the better 3 step chargers put out a max 14.5V, or less, as an absorption charging voltage, before dropping further during "Float" mode. In most devices this max voltage is a set value and not adjustable. That really isn't enough to completely top off flooded/wet cell batteries to 100%. Over time the slightly under charged batteries will deteriorate faster than batteries charged to 100% Slightly undercharged batteries will also store less energy than a battery that is charged to 100%.
When looking for Solar Panels look at their specs. If you are building a 12V system, get one rated as such. Watts can vary depending on your preference. Dimensions also depend on the area you have to work with. For surface area, my thought is to get the highest possible wattage for the real estate you will be using. After that make sure the VOC spec is somewhere in the range of 20 to 22 Volts. VOC stands for "Voltage Open Circuit". It is the measurement with a meter across the output panel voltage, in full sun, and no load connected. Next make sure the VMP spec indicates it is rated between 17 and 19 volts. VMP stands for "Voltage Max Power"
I ordered a TriMetric SC-2030 Solar Charger and a companion TM 2030-RV Meter/Control, plus a 500 amp shunt and a remote Battery Temperature sensor.
These components will provide:
Remote Meter and Control of the SC-2030 Charger
Battery Temperature sensor and control
500 amp Shunt
Cost including Shipping $319.50
Perhaps over kill but I want to be able to add more batteries, more panels, and an inverter in the future. I do not want to change out components if or when I upgrade.
As I indicated I also want the ability to adjust the charger output voltage. To increase it from a fixed max voltage to a higher voltage to match up with the Battery specs max charge rating of a Flooded/wet cell.....typically to around 15V. Or to adjust in the case of AGM battery use, to a lower charging voltage. I am talking in general about the Absorption charging voltage since the Absorption charging voltage and Float charging voltage differ even within a given charger.
You do have to know your devices that are plugged in can handle this voltage change.
Those that dispute my thoughts on adjusting the charging output can research on their own, then come to their own conclusion. Check the battery specs of what you will be using. Other people may sight that this increase in output voltage will overheat the battery....hence the battery temperature sensor that also connects into the SC-2030 and further overrides any charge settings, the charger is following, should the battery become too warm. I am only trying to get max charging when my panel(s) is/are converting the suns energy. And to store that energy as quickly as possible. I am only passing on what I am doing, and things I learn along the way. I am not trying to trigger a debate on chargers, voltage, or batteries.
The SC-2030 is Solar Charger for either a 12V or 24V system and rated at 30amps. The unit will work on flooded/wet cell, AGM, or GEL Cells (They are pre-set for flooded/wet cell batteries). The Unit can be set for the other outputs in less than a minute. Pre-sets on 12V are:
Flooded/Wet =14.6V Absorption and 13.2V Float
AGM or Gel =14.3V Absorption and 13.2V Float
The TriMetric TM 2030-RV will give me a remote monitoring ability to meter and see what is happening with my batteries and charging. This remote will also give me the ability to alter the charging voltage to the higher sittings I will be using to insure my batteries are charged to 100%.
The Solar Panel I ordered is a Kyocera KD140SX-UFBS 12V 140 watt Panel with Junction Box. I wanted max wattage, and simple connections.
You need panels rated for charging batteries. Panels with specs outside this range are not designed for charging batteries. This panel is rated at 12V, 140watts, VOC=22.1V VMP=17.7V and comes with a standard Junction Box for terminating the power wires. I did not want special connectors to contend with, try to mate up a wiring harness, or try to replace/repair during trips.
Cost including Shipping $315.49
Check back often. Over the next few weeks I hope to have the system up and working. I will provide photos and wiring diagrams.
Parts Purchased from & recommended solar vendors.
BACKWOODS SOLAR I purchase my TriMetric Charger and Controller, as well as a Battery monitor/sensor and 500 amp shunt from Backwoods Solar. They also have a great free catalog that is packed with all kinds of info as well as what they sell.
NORTHERN ARIZONA WIND & SUN I purchased my solar panel here. I had called a company in Massachusetts first. When they quoted me shipping to Nevada I said wow! They actually recommended I call Northern Arizona Wind & Sun since they are so close to me. Hard to find a business willing to do that...my hats off to them as well. It also made me feel like NAW would take care of me. I paid a little extra for 2 day delivery.
The past week had me gathering the necessary metal tubing and parts to construct a roof rack for my trailer. I did not want to drill holes in the roof. I will be fabricating a rain gutter mounted rack. I have to span about 8 1/2 feet and will be using 1x1 and 3/4x3/4 16 gauge steel tubing.
I had several designs in mind to construct the gutter clamps. After pricing material and hardware at Home Depot I found it easier and probably nearly as cost effective to purchase heavy duty pre-made clamps from Smittybilt. I purchased these at 4wheelparts.
I am using their Defender series Rain Gutter Clamps (P/N: S/BHDS-4) That gets me (a set of 4) clamps and hardware for $104.99. The 90° metal part that would be used to attach their rack will be discarded. The clamp back plate will be modified by welding it to a piece of of flat steel about 14X3 by 1/8 inch thick to create a vertical upright. The cross member 1x1 steel tubing will be welded to the uprights.
The roof line high center point requires 12 1/2 inches of clearance, which includes a 2 inch gap in case of flexing. The uprights will be left high enough to allow stacking a second 1x1 cross member in case the 8 1/2 ft span is found to flex too much using only one cross member. Once weight testing is competed with the basic bar system the additional bar will be added, or the uprights trimmed and finished with the one cross bar.
Note: It was a good thing I anticipated the fact I might have to double up the cross member. I had made my vertical extra long just in case. The vertical risers ended up being 14.5 inches high. My cross members are 100.75 inches. The cross member with just one 1x1 tubing flexed too much. Adding the second 1x1 tubing beefed up the cross member nicely. My solar panels weight 35 lbs each so there should be no problem supporting 70 lbs.
|Vertical Riser Welded to the Gutter Clamp|
|Vertical welded to Crossbar and 45° Brace|
|Rough finished rack component|