With the free electricity from the sun, most people, given the resources, should be able to set up solar electricity for the home, RV (recreational vehicle), shed and more. Also, if you live in an area that has no access to the main grid electricity lines but has some or plenty of sun, setting up your own solar electricity system is the way to go to run some appliances and lights. Here is what you will need:
SIZING: First and foremost, you should decide upon or know the size of load or appliances you will be using the electricity for. Depending on how much money you wish or can invest in this, you will decide on what appliances to add or deduct. You then decide upon the size of the battery bank and solar panels. The size of the battery bank and size and number of solar panels will depend on the availability of the sun in your area and when you are most likely to use certain appliances. If you live in an area that has plenty of sun all year-round (like most parts of Africa), I suggest the following ratio: (batteries) 100 amps to 120 watts (solar panels). In areas that have the winter season that comes with less sun, I suggest you double up on the batteries at a ratio of: (batteries) 200 amps to 120 watts (solar panels). In this article, we are assuming a 12-volt DC (direct current) system.
SOLAR PANELS: These are for harnessing the sun’s light energy to charge the batteries. Mixing solar panels of different watts and age is very highly discouraged as that may tremendously reduce the efficiency of the higher-watt and newer solar panels in the pack. Each solar panel in a connected group, in parallel or series, will only perform as good as the worst solar panel in the pack. For example, if you mix 120-watt solar panels with 50-watt solar panels, the 120-watt solar panels maximum performance will be reduced to the present performance of any of the worse-performing 50-watt solar panels.
BATTERIES: These are for storing the solar energy harvested by the solar panels. Mixing batteries of different amps, age and chemistry is very highly discouraged as that may tremendously reduce the efficiency of the bigger and more efficient batteries in the pack. Each battery in a connected group, in parallel or series, will only perform at the highest level of the worst battery in the pack. For example, if you mix 100-amp batteries with 50-amp batteries, the 100-amp batteries maximum performance will be reduced to the present best performance of the poorest-performing 50-amp battery.
Battery bank size: Your individualized battery bank depends on how many appliances you intend on using your solar energy for and how much total energy they consume. It may also depend on the time of the day you use such appliances. It also depends on how much sunlight your solar panels will tap into. If you live in an area that has plenty of sun all year-round (like most parts of Africa), I suggest the following ratio: (batteries) 100 amps to 120 watts (solar panels). In areas that have the winter season that comes with less sun, I suggest you double up on the batteries at a ratio of: (batteries) 200 amps to 120 watts (solar panels). In this article, we are assuming a 12-volt DC (direct current) system.
Battery longevity: Your battery bank will most likely last much longer if you never drain it to any less than 50% and protect it from the bitter coldness. So, the lowest you should ever drain your battery bank should be down to 50% at the battery power indicator and/ no lower than 11.9 volts for a 12-volt battery bank. Also, if you live in an area that has cold winters, adequately insulate your batteries during the winter month/ weeks.
CHARGE CONTROLLER: To prevent the solar panels from overcharging the batteries, and to prevent electricity from moving back into the solar panels when the sun goes down, a charge controller is an absolute necessity. The are two types of charge controllers: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). PWM charge controllers are way less expensive than MPPT controllers but are slightly less efficient. MPPT charge controllers are more expensive but are about 10% – 15 % more efficient and have more control settings and customization options than PWM controller. If you are on a budget, PWM charge controllers will do fine.
How do you determine the size of the charge controller(s)? The size of your solar array determines the minimum size of your charge controller(s). This is my easy formula for determining the minimum size of the charge controller needed: In a 12-volt DC system, solar array size (in watts) divided by 12, which equals to the minimum required amps of the charge controller. For example, if you have three solar panels of 120 watts each, that gives you a total of 360 watts. 360/12 = 30 AMPS. So, your charge controller in this case should be at least 30 amps. Never apply more solar panel watts to a charge controller than the stipulated solar panel watts as that will overwork and destroy the charge controller. It is perfectly fine to use a bigger charge controller than needed for the solar array. Whenever using more than one solar panel, I highly recommending separating the solar panels into at least two groups to use at least two charge controllers as that may increase efficiency when one solar array is not affected by the inefficiencies of the other.
CIRCUIT BREAKER: To prevent equipment damage related to overheating resulting from short circuits and/ too much current, circuits breakers are an absolute necessity. To size a circuit breaker, you get the number of amps of the appliance you are protecting and multiplied that by 1.25. For example, if you are protecting a battery bank that is 240 amps, you multiply 240 by 1.25 = 300 amp (which is the appropriate size of circuit breaker to protect this battery bank. If you are wanting to protect a charge controller that is 30 amp, here is the calculations of the size of the circuit breaker: 30 x 1.25 = 37.5 amps. If there is no circuit breaker of that size, in this case there is no circuit breaker of 37.5 amp, you use the next size up, which in this case you would use the 40-amp circuit breaker. You can use a fuse in place of a circuit breaker. The downside with fuses is that each time a fuse blows, it has to be replaced. For circuit breakers, you simply fix the problem and turn the switch back on.
CONVERTING WATTS AND AMPS: If an appliance’s power consumption is given in watts but you would like to know how many amps that is, you divide the watts by the voltage of the appliance. For example, an inverter that is 1500 watts of 110 volts: 1500/110 = 13.64 amps. To convert amps to watts, you multiply the amps with the voltage of the appliance. For example, you want to run a drill that is 7.5 amps and of 240 volts, but you are wondering how many watts those would be: 7.5 x 240 = 1,800 watts. To convert kilowatts into watts, you multiply the kilowatts by 1,000. For example, if you would like to know how many watts are in 0.36 kw: 0.36 x 1,000 = 360 watts.
FUSES: It is quite hard to find DC circuit breakers beyond 300 Amps, but it is much easier to find fuses beyond 300 amps. So, here are some fuses beyond 300 amps:
BATTERY CAPACITY MONITOR: The charge controller monitors and displays the capacity of your battery. However, if you would like to add some other easy and quick to use means of watching your battery capacity, here are some options:
BLOCKING DIODE: If you have any concerns that, for some reason, the charge controller may malfunction releasing electricity from the battery bank back into the solar panels, you should include a blocking diode before the positive (hot) line from the solar panels enters the charge controller. Blocking diodes are sized the same as circuit breakers by multiplying the size of the charge controller in amps by 1.25. For example, if a charge controller is 50 amps: 50 x 1.25 = 62.5 amps. If the size of that blocking diode is unavailable, you should use the next one up. For example, if 62.5 amps is unavailable but 70 amps is available, you would use the 70 amp.
BATTERY PROTECT/ AUTO DISCONNECT: This will disconnect the battery bank from the load at a pre-set voltage to prevent the load from over-draining (over-discharging) the battery bank.
INVERTERS: If you plan on using certain appliances that use AC (alternating current) instead of DC (direct current), you will need the inverter(s) to convert DC power from the battery to AC power.
STEPUP/ DOWN: It is hard to find 220/240 V (Volts) AC inverters with good customer reviews. Because of that, I could not come up with recommendations. However, you can use a 110/120 V AC inverter but add a step up/ down to step up the voltage from 110/ 120 V to 220/ 240 V AC for 220/ 240 V AC.
TOOLS: Possessing and using the appropriate tools certainly makes your work faster and more enjoyable. Here are some tools:
MORE TOOLS, PARTS AND APPLIANCES
I hope I made your DIY off-grid solar project much easier with most of the basic instructions and accessories all in one place. Enjoy your solar project(s).
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