Simple Photovoltaic Power, by A. DoItYourselfer

This article presents my photovoltaic power experiences to give fellow do-it-yourselfers an understanding of what it takes to use the sun for energy.

I am a 69-year-old carpenter with experience in residential, commercial and industrial construction. I abhor relying on others for needs. So that is what drove me in the area of energy, especially stored energy. By “stored energy, I mean propane, solar battery systems, stored food, and so forth.

I live in Arkansas which is considered a subtropical climate in late spring to early fall. The heat in summer coupled with humidity from the Gulf of Mexico is terribly oppressive, even to us natives. And for this reason you need to at least move the air in summer to help with these conditions. I set out on my solar journey about three years ago. I decided that my goal would be to have a system that would run lights (LED), operate fans, and charge Dewalt 20 VDC tool batteries. I ended up with 3 systems and wasted a lot of money. But the “good thing” that I achieved is redundancy (i.e. having backup systems).

My First System

A Zamp 200P (P means Portable) system. I wanted to stay in the 12 volt arena versus the 24V, 36V or 48V systems because I better understand 12V systems because that is what automobiles, boats, etc. use. I also wanted to stay in the Recreational Vehicle arena because of portability as well as the simplicity (plug and play). The Zamp 200P system included:

  • 2 – Zamp brand 100 watt solar panels (for a total of 200 watts of input on a clear day)
  • 1 –  Z15AW (Z means Zamp, A means Amps, W means weatherproof) charge controller

I added the following to the system from separate vendors:

  • 1 – Xantrex ProWatt 2000 inverter (an 1,800 Watt invertor which takes DC battery power and converts it to 120VAC (household) power.
  • 2 – 6-1 volt golf cart batteries connected in series (instead of parallel connection) which make it a single 12 volt battery. These are lead acid batteries similar to a 12V trolling motor battery.

Various wires, cables, connectors, fuses etc.. The Zamp instruction manual explains diagrams to connect all this and is simple to follow).

This system cost around $1,900.. This system would run lights, fans, and charge tool batteries. But it is just enough power to make you wish you had some serious power. This system might be good for emergency storm backup power for 24 to 36 hours of cloudy weather. However, it whetted my appetite for more, so I continued my journey.

My Second System

I kept my first system intact, as a backup. My second system consisted of:

  • 2- 180-watt 12 V solar panels from OFFTHEGRIDRV. The proprietor, J.R., was extremely helpful.
  • 1 – Victron 100/30 maximum power point tracker (MPPT) controller. (100 means volts and 30 means amps). The Zamp 15AW controller is a Pulse Width Modulation (PWM) technology controller. PWM is easier to use (plug and play) but the MPPT is more efficient. I am in no way a techie but the MPPT seems to be better, but more expensive.
  • 1 – ProWatt 2000 inverter (the same type that I previously mentioned).
  • 2 – Battleborn 12V lithium batteries.

Note: Thusfar, I’ve only bought monocrystaline panels versus polycrystalline. I’ve read the monocrystaline panels have a longer service life and better reliability.

Oh my goodness! This system ran lights, fans, battery charger (for tools) and it ran a Wal-Mart 5,000 BTU air conditioner for two hours and had battery capacity left! It also ran a Wal-Mart dorm refrigerator for even longer. It also ran a pancake air compressor for my nail gun. The difference in the two systems is mostly the Victron charge controller but especially the lithium batteries. This system cost just under $4,000. My appetite was growing now. But the inverter was still too small for a “hard start” circular saw (15 amps).

My Third System

For my third (and presumably final) system, I bought:

  • 2 – HQST 100 watt polycrystalline solar panels (less expensive)
  • 1- Victron 100/50 charge controller (100 means volts and 50 means amps. With this larger charge controller I could add more panels to gather more power)
  • 1 – Xantrex Freedom X3000 (marine grade) inverter.
  • 2 – Battleborn 12V lithium batteries (2 more for a total of 4. These things are $1,000 apiece but worth it!) If you use lead acid, AGM, or other type batteries you will see what I mean.

So, for 760 watts of panels, Victron 100/50 controller, Xantrex 3000 watt inverter, 4 lithium batteries plus cable, wire, fuses, connectors, etc. this system cost $7,000. But now I can run fans, lights, a Wal-Mart 5 cu. ft. freezer, a dormitory-size refrigerator, (freezer and fridge run 24/7), air compressor, (small), circular saw and battery charger. I later added more components so that the other two initial startups would be complete for redundancy.

This power output serves me well for my solo use at my cabin. If the nine members of my immediate family ever to need to be here, then we will have to be very conserving of our power. No leaving a room with the lights still on. I have tried to think of things I could do that no one else in my area could do for barter and one of the things I thought of was ice. In a grid-down scenario with a freezer available, I can trade ice.

I had a well dug and bought an Aquatec 4000 slow well DC pump. This thing is powerful. I was running it on 12 VDC (it will run on 24VDC) to fill my water tank and gravity feed to the cabin (about 9 PSI but with no less then 3/4’’ PVC pipe it feels like 30 psi), I later bought a 24V/250 watt panel from Craigslist and the pump takes half the time to fill the tank.

Morals of this story, And Some Reminders

If I had had more experience with solar then I would have first built System 3 and quit. (although I don’t mind having the backup).

I mounted my panel racks on a pipe (2” galvanized, Schedule 80) so that I can swivel them to follow the sun and also adjust the angle of the panels for the season. This is worth doing.

With a PV power system you will have to be conservative but it is better than being without power.

Get a PURE SINE WAVE inverter to run delicate devices (computer, TV, Phone, etc.)

Volts X Amps equal watts

Learn about series versus parallel versus series-parallel wiring connections for panels and batteries.

I believe that a 24 volt system would be more powerful than a 12 volt but I need simplicity. I only use the 24 volt panel for the water pump.

I have to stay away from complexity to do this myself (complexity equals grid-tie, inverter\chargers, higher voltage panels, etc.)

I tied my inverter in to my off-grid breaker panel by building a short 10 gauge wire extension cord which plugs or hardwires into my inverter. (Note: I am not connected to any grid). If you are connected to the grid then you will have more complexity and danger/liabilty unless you install a proper grid-tied breaker panel to prevent backfeed to the grid that could electrocute a power lineman attempting to do a repair.

Always use larger gauge wire than the instructions call for. (In other words, where it called for #12 wire, I used #10.)

Never use solid wire for DC voltage. Use stranded wire.

I used welding cable from my batteries to the inverter.

Pay attention to fuses when called for. I used automobile fuses from the auto parts store up to 60 amp.

Forget any batteries except for Lithium, unless you have to use lead acid/AGM/Sealed for budget reasons. The Battleborn have a battery management system (BMS) installed. This is crucial and the Battleborn are plug and play-simple.

If you can jump an auto battery you can probably do this.

I spent more money than I should have because of the experimental first two systems but I am okay with that, for the sake of redundancy and independence.

If I am supporting 10 family members, then we will have to be very conservative with power use but we will be VERY much more comfortable.

Don’t get anything less than a 3,000-watt pure sine wave inverter.

Use the MPPT charge controller.

The batteries and the charge controller have to be in the same temperature/climate environment. The inverter can be in a different environment.

Lithium batteries don’t put off any harmful gases.

A closing verse and A Movie Suggestion:

Trust in the Lord with all thine heart; and lean not unto thine own understanding.

 In all thy ways acknowledge him, and he shall direct thy paths.” – Proverbs 3:5-6

Do see the movie series “The Chosen”. Best I have ever seen, and I am not a movie person.