Greetings All! Here is my first attempt at an in depth and exhaustive explanation/summary of my off grid power set-up down here at the ol’ Solar Cabin! Thanks for reading! Let me know what you think, and ask any questions that arise! P.S. This is my first draft… also, my first blog/website/solar set-up!
With 600 watts (0.6 kw per hour) of Renogy Solar Panels (150 dollars each on Amazon, with two more on the way), I can run a fairly large mini fridge/freezer and soon a chest freezer, each at 30 watts an hour. I can also run a handful of 4-7 watt LED and CFL light bulbs quite easily. I can use a microwave, electric stove burner, electric tea kettle, coffee maker, convection toaster oven, most home and kitchen appliances, though I am soon purchasing/reclaiming a wood cook stove, as the 1000+ watt (1 kilowatt, 1 kw) draw from some of those cooking appliances is definitely do-able (especially on a sunny day), but not for long enough to cook a turkey or something. Any appliance over 250 watts should be used sparingly if at all, and possibly only during sunlight hours to help increase battery longevity. I do all my laundry and dishes by hand, as the prolonged 1kw+ draw from those types of appliances is too great for a set-up of my size. Fridges, freezers, light bulbs, laptops, televisions, cell phones, fans, pumps, and other small appliances are very low wattage compared to anything that heats up the likes of food, water, and your home, so keep that in mind.
For a battery bank, I currently have 4 AGM 100Ah Sealed Lead Acid Batteries (also from Amazon for about 150-170 dollars each), wired in parallel to stay at 12V (24V is possible too, with the right setup). With this battery bank, I have 4.8 kilowatts of storage capacity (100Ah per AGM Battery * 4 batteries * 12 volts = 4.8 kilowatts). I will probably get 1-2 more batteries, just so I am only draining my 12V battery bank down to 80%+ charge, rather and 70%+, as the happier you keep your battery bank, the longer it will last you in its lifespan (which could be up to 5-10+ years).
Appliances and Battery Drain
With all my light bulbs, laptops, cellphones, appliances, mini-fridge/freezer, a 6-gallon “Eco” water heater, an 8-gallon saltwater fish tank, and my television and Xbox, I am only using about 50-100 watts per hour. At that rate, considering 15 hours of darkness/shade, when I am relying solely on my AGM Battery battery bank, I am using roughly 1.13 kw (75 watts per hour *15 hours of shade/darkness). This results to a drain to 76.5%, which is perfectly acceptable in the Solar/RV community.
Battery Charge Efficiency
This is assuming that my batteries have received enough solar to reach 100% charge, during that previous day. With my 600watt Renogy Solar Panel array, lets say at 30% efficiency due to clouds or inclement weather, I may still receive 200 watts per hour, lets say for up to 9 hours due to the cloud cover dispersing sunlight, allowing prolonged hours of indirect sunlight, with less hours of panels spent in obvious shade. That means on a cloudy day I could produce around 1.8kw (9 hours * 200 watts per hour average, with proper tilt and the addition of reflective mylar sheeting), while a sunny day could produce over 3kw (5 hours of direct sunlight * 600 watts per hour from solar array), both being enough to run 75 watts per hour for 24 hours a day ( 75*24 = 1.82kw), without ever dropping the AGM Battery battery bank below a 75% charge of ~12.36V, down from 12.6V+ at full charge.
Battery Bank Longevity
As for longevity, the panels may last 30-40 years, with 5-15 year warranties being commonplace. This allows for the ability to save enough money through lowered/negligible monthly power bills to pay off the solar array, battery bank, cables, connectors, inverter, and charge controller (a complete setup!), within 5-10 years.
Inverter and Charge Controller
When it comes to inverters and charge controllers. I use and recommend the Renogy Rover 40amp 12/24V MPPT charge controller (210$) and the WindyNation Vertamax 1500/3000watt (running/peak) 12VDC to 115VAC Pure Sine Wave Power Inverter (250$). The Renogy Rover MPPT charge controller has a 12/24 volt step down ability, which allows for the wiring of the Renogy Solar Panels into a 24V parallel/series array, which will be stepped down to 12-14V, the proper voltage to charge a 12V AGM Battery bank, while at the same time, increasing the amperage, allowing an equal and almost guaranteed more efficient flow of watts from your array. The Vertamax Pure Pune Wave Inverter by WindyNation is capable of powering everything in my house, using the 1500 watts of inverted 12V DC to 115V AC power, though not everything at same time, of course.
Rain Catchment, Berkey Filter, and Hillbilly Wood-Fired Hot Tub
With the new addition of my very own hillbilly wood-fired hot tub to bathe in, I am just about 100% off grid, with the only exception being a bathroom ceiling light and fan, which will soon be replaced with solar powered equivalents. I am also soon to be 100% off grid for water as well, using a rain catchment system accompanied by a Berkey Filter for drinking water sanitation, a 50-gallon water storage barrel and 275 gallon IBC storage tote, a shallow well with a pitcher pump, a solar lake pump for lawn and garden irrigation, a wood-fired lake-fed hillbilly hot tub/shower, and last but not least, a composting toilet.
Total System Cost Breakdown – 2000 Dollars
- Six 150$ 100watt Renogy Solar Panels = 900$
- Four 150$ AGM 100Ah Batteries = 600$
- One Renogy Rover 40 Amp 12/24V MPPT Charge Controller = 210$
- One WindyNation Vertamax 12V DC to 115V AC 1500/3000watt Pure Sine Wave Inverter = 250$
- Cables, Connectors, and Fuses = 140$
Through the use of solar and alternative energy/lifestyle, I am currently saving about 150-200 dollars a year in monthly power bills, not including the thousands of dollars I am currently saving through the first step of going on solar/off grid, the downsizing and replacement of energy hogs in your home/kitchen with energy stars. At a rate of 200 dollars a year, I will pay off my 2000$ solar setup in roughly 10 years. Though, at that time, possibly 5 years earlier or later, the AGM battery bank will likely need to be replaced. Hopefully by the time this is required, batteries will be much less expensive (and more efficient), as the technology involved in improving battery capacity/lifespan becomes increasingly more competitive as solar/consumer demand increases.
-Blake Rasmussen, Founder MySolarCabin.com