No power in Asia

I have lived in Asia for three years and there is often no power there. The only things available are diesel generators and small inverters for lights. I tried using fans with the inverter, but the fans burned up.
I figure that there must be ways to build a system with batteries to run other appliances like fans, refrigerators and air conditioners, but I don't know anything about it really. I am also interested in using solar power. I would like to be able to get what I need for the system while I am here in the States.
Does anybody know where I can look that will tell me what I need to buy in order to run different appliances?


  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: No power in Asia

    you will firstly have to know the power requirements of what you plan on running(max watts used at one time) and for how long(watthours). this is needed to know for many reasons as it determines the battery bank size, the inverter size, and the number of pvs you'd need to recharge the batteries. conservation and carefull planning will extent your abilities.
    as to your inverter blowing out fans, this is most likely because of the inverter being a modsine inverter. a sine wave inverter should be used for electrical motors and that would include the compressor and fan on a refrigerator. anything that could run by battery like 12v cfls or 12v fans could save on the conversion losses of going through an inverter. you should do more reading if you can in order to familiarize yourself with options you would like to do or to have. only you will know what you wish to power and when and it'll be your money to do it with so costs are a factor too.
  • System2
    System2 Posts: 6,290 admin
    Re: No power in Asia

    From your post we can assume that grid connection is a non-starter, that rules out a good number of inverters. The fact that you burn fan motors out suggests that your "small inverter" is a modified sine wave, essentially a square wave. Many posters have reported similar results, good thing you haven't plugged your refrigerator into it yet.

    I created a calculator that will do most of the work if you plug in the values on each of the worksheets, it is attached to this post at the bottom. You will need Excel on your PC, some folks here report that some opensource spreadsheet applications work as well. Note that I wrote it only for solar powered systems but the battery selection worksheet should help size your battery for generator use(if you are going that route).

    The major components for an off-grid PV powered system, in order of current flow, are PV panels, battery charge controller, battery and inverter. You will also need appropriately sized wiring, disconnects and current limiting devices (fuses or circuit breakers) between these major components.

    PV panels come in different open circuit and short circuit voltages, both vary depending on cell temperature and both are significant regarding charge controller selection. The open circuit voltage (high voltage) can damage charge controllers. The short circuit voltage is important because it must be higher than the battery bulk and/or equalization voltages when the panels are hot. If not, the battery will likely never be charged completely (the battery will suffer a short life).

    Quality charge controllers are typically either Pulse Width Modulation (PWM) or Maximum Power Point Tracking (MPPT). The PWM type typically must have a PV array voltage higher than but near the battery voltage. As a battery charges, the controller will begin to modulate voltage pulses, shorter and shorter pulses as it reaches 100% state of charge (SOC). MPPT controllers can take a higher voltage PV array and down-convert the voltage to match the battery - but only as long as the VOC of the array does not exceed the charge controller's open circuit voltage maximum specification. The major players in the MPPT controller field have a 150voc limit. Higher voltage PV arrays, relative to battery voltage, allow you to use smaller gauge wire from array to MPPT controller - less espensive wiring but the controller is more expensive than a PWM. Decisions, decisions.

    Batteries come in different construction types, physical sizes, voltages and amp hour ratings. Flooded lead acid (FLA) batteries are the least expensive but may have a higher self-discharge rates - usually not an issue except with PV arrays that are too small for the battery they are charging. FLA's can be equalized to help recover from poor maintenance or electrolyte stratifcation (higher specific gravity electolyte at the bottom of the plates, lower SG electrolyte at the top). Absorbed Glass Mat (AGM) batteries are less forgiving of charge voltages, typically cannot be equalized but may have a higher efficiency (amp hours in / amp hours out) and have a lower self discharge rate than FLA batteries. The calculator will correct for this by allowing you to put in the battery efficiency. You also do not want to discharge your batteries deeply so you need to have enough capacity to cover your nightly loads or cloudy days with only a small discharge. Then you need to make sure that your PV array can adequately charge the battery the next day when the sun is out. If not, you have what's called "defecit charging". Another battery killer.

    Inverters are either modified sine wave or sine wave. The sine wave inverters create a wave like the utility, motors and sensitive electronics like it like that. Mod sine inverters have square edges and a number of steps per cycle, the more the better (as far as mod sine inverters go). Square wave inverters are notorious for burning out motors and some electronics. Unless you have unusual requirements, size your inverter(s) to operate at about 33% to 50% of capacity, that is where the "sweet spot" of efficiency is. If you have intermittent high power requirements, you may want to consider different size inverters, a large one that you can switch on and off as needed and a smaller one for your normal loads. For example, lights, fans and refrigerator may only require 200 watts. To get good efficiency from your inverter you would want to use a ~600 watt inverter. If you have a 1000 watt microwave, the 600 watt inverter would not power it. You might need a 2000 watt inverter to run it but that inverter would be rather inefficient running your 200 watt normal load.

    Long story short, every decision you make will impact every other decision. The good folks here will help you figure it all out.

    I hope everyone had a merry Christmas!

    Bad Apple