Solar systems in homes should be installed by professionals as there are many risks and hazards. It should be fitted with suitable AC and DC wiring to reduce fire risks, proper earth grounding to eliminate shock and lightning threats, correct battery and placement to minimize gas buildup and an accurately sized solar array or panel.
Solar energy in itself, isn’t something new. The Solar Foundation reports that currently over one hundred thousand people are employed and are working successfully in the United States solar industry. “Apple” as well as “Google” is making use of solar energy to run their companies. It is a greener form of energy and is renewable which can be used to any extent unlike the exhaustible form of energies. It is been reported that Apple will be manufacturing solar panels to help improve the usage of solar energy instead of fossil energy.
Using Solar Energy Today
Technology plays a key role in such shifts. Since the twentieth century, technology has been the central change bringing nucleus. When these changes and system shifts are combined with problems that humans create, such as population explosion or global warming, it often forms a reaction that human beings cannot control at all. This may be termed as the environmental reaction.
Using solar energy is one of such major developments. Technology enables us to use the power of the sun to harness electricity. And a good off-grid solar power system is one of the best examples of solar power mixed with technology.
So, how can you make your own small off grid solar power system?
This is a complicated task and should be undertaken by professionals. But many enthusiasts and people want to install a small solar power system in their cottages or vacation cabins where there is no electricity. This guide will show how to make your own solar power system based on battery for lighting a few bulbs and powering a DC freezer or water pump. You need to stick to the guide and use all the items as mentioned specifically.
Here is a look at a step by step guide that will help you do it easily.
Words of caution
Using 12 volt DC equipments and tools to build anoff the grid solar power system poses minimal risk of shock threats and many lights and electrical appliances can work on this load. Still it is essential to practice caution as use exactly the same materials instructed.
The deep discharge batteries are loaded with stored amps ranging in hundreds that can melt wires and start a fire. A good way is to purchase ready made solar power kits available in the market.
Battery power and amount
The number of batteries and how many you will need depends on your power consumption. Generally two 12 volt batteries will suffice for turning on the light in two to three rooms. If you want to add a DC freezer or pump to the list then you will require two to four 6 volt batteries. Refrain from using standard car batteries as they are not suited for regular household use. That is unless you have access to plentiful and very cheap secondhand ones, they will last a while and can be used as a stopgap.
Ideally you’ll be using 12 volt RV batteries or the 6 volt batteries used in golf carts. They can be found easily and the price is not very high. GEL or AGM version batteries can be a bit expensive but they do not need any maintenance and cut down the threat of explosive gases.
Sealed batteries can be useful in a cabin scenario with not much space to spare. Battery banks in colder regions with temperatures less than 35 degrees should be properly insulated to conserve their battery charge.
Solar panels and array
The number of batteries installed in the bank decides how many solar arrays you need. The location of the panels is also an important factor that comes into play. The less sunlight the panels get the more you’ll need. A poor climate will obviously need a lot more panels than a spot in the middle of a desert.
Location of Solar Array
Solar modules are lightweight and can be mounted on poles, roofs, upon a raised frame mounted on the ground or any place receiving enough sunlight. The system should be properly put into place using durable and long aluminium screws that bolt into the main frame or pole. There are cases where strong winds have torn solar arrays from their fixings.
Angle of Solar Array
Most of the sunlight comes from the south so your solar modules should be faced in that direction. Some places receive sunlight during later part of the day and making the angle towards southwest is beneficial. The optimum all year round performance can be achieved by tilting the panels at an angle equal to the region’s latitude. A lesser tilt results in more power output during summer while a steep angle works for the winter. Adjust the angle of the solar modules according to the time of the year.
Size of Solar Modules
The wattage you require to charge your batteries will impact the array sizing. The basic 12 volt solar modules generate lesser than 100 watts. Typically a single deep-cycle 12 volt marine/RV battery or a 6 volt golf cart battery stores around 1 kWh of electricity at a time when discharge is 50%. Considering that, four to five hours of sunlight in a day needs to produce approximately 200 watts of solar module power to charge a battery fully in one day.
The loss of sunlight can be encountered by increasing the number of arrays or cutting down on power consumption. People sometime think it is better to use numerous batteries and solar arrays through parallel connection but there are many problems. It is wise to go for high capacity arrays and batteries which last longer and perform better than local and cheap low range models.
Precautions for Wiring and Safety Equipment
The amount of amp current increases even when the voltage is less in case of DC connections. An electrical appliance working on 120 volts AC requires ten times more amp current while running on 12 volt DC. The wattage remains unchanged even when voltage fluctuates. For example, two light bulbs of 100 watt require 1.8 amps to glow at 120 volt AC (200watts/120 volts). The wiring can be done using a #14 sized wire with an amp rating of 15. But on 12 volt DC, the same bulbs draw a load of 18 amps (200watts/120 volts). So it cannot be wired using the above sized wire of 15 amp rating. The same sums can be used for 240volt areas.
Using low voltage powering system does not cut down risks of fires or overload. Every wire carrying a load in the cottage has to be fitted with proper fuses and circuit breakers. Generally the DC compatible fuses and circuit breakers are much expensive and larger than their AC counterparts of the same wattage. They are not easily available in shops so it can be a hard task to get one.
One product from Square, the D “QO” range of AC circuit breakers is compatible with DC supply up to 48 volts DC. You can purchase the Square D “QO” subpanel with eight circuits and 10 to 15 amp circuit breakers of the same model for single poles. Do not go for fixtures used in cars as they are unfit for household use.
The power generated by your solar power system will not last long if you use standard light bulbs. So you should buy energy efficient lighting and appliances to conserve the power. The local boating or RV electrical supply store is a good place to find proper lighting gear and fixtures, which is made easier because you’re using 12 volts..
Most of the 12 volt lighting and appliances are weather resistant and fit for outdoor use. It is better to go for lighting systems with internal power switch as it eliminates the need of additional purchases. Furthermore, DC switches are difficult to come by and the process also increases the total expense of wiring.
The cottage can be provided with basic plumbing system using a 12 volt DC pressure pump. It can send the water to the bathroom shower or the washbasin without the need of a deep well pump. The storage can be placed on the cottage and can be refilled with stream water, river water or any clean source nearby.
The water may not be suitable for cooking or drinking unless it is a clear running stream. You can boil the water or use packaged drinking water. The water tank should have proper outlets located at the lower part so that water can be drained out. It is necessary in cold climate to prevent freezing inside the tank.
Refrigeration or Freezer
Using a refrigerator on a solar power system hugely increases the load. It means you have to have larger arrays and battery backup. Another alternative is buying a specialized off the grid 12 volt DC freezer or a propane powered one.
This can be bought from the RV or the boating store and are quite expensive. They range around £600 to £1200 but can be a fruitful investment if you want to use them for a long term. Sunfrost and Sundazer companies have some 12 volt DC freezers which consume less power and can work efficiently on a solar system.
All wiring and fixtures should be used in accordance with regulations where ever you are. It is better to use a wire of larger size if the total wire length required in more than 50 feet. It is safe even though the load may be small. We already discussed that wiring for 12 volt DC carries 10 times more amp current than 120 volt AC. So increasing the wire sizing reduces the electrical resistance and leverage’s output. Opt for copper wiring as they have higher amp rating than cheap aluminium wires. Also use copper connectors and wiring equipment to save on cost and hassle.
Location of Circuit Breaker
Your DC lighting equipments and appliances may not come with power switches. To makes things convenient, place the circuit breaker near the front door. This way you can switch the loads easily through the circuit breaker. AC switches do not work with DC connections and should never be used. IF you want a plug point, you have to buy one marked for DC connections.
Solar Array and Battery Wiring
The solar modules are equipped with male and female connectors and the smaller ones have an electrical junction box on each of them. They have to be connected together through parallel wiring for the 12 volt batteries. Using a combiner box is helpful which cuts down the hassles of wiring. A charge controller is necessary to keep the batteries safe from overcharging.
There must be a charge controller connecting each module to the battery. You will need a large capacity charge controller if you run more than four solar arrays. You can cut down on parallel wiring and do it in series to get 24 or 48 volt solar modules connected with a 12 volt battery bank. Install a fuse on the positive wire connecting the solar module and the charge controller. Put another one between the charge controller and the battery.
We are operating at low voltage, still it is necessary to have a proper grounding for the power system. It can get damaged by lightning or produce shocks. The solar arrays have specific holes built-in where you can connect a bare copper wire and connect to the ground. You should use a ground rod and connect the bare wire to it. The other end can be screwed with a plate to the grounding hole in the array. Proper grounding needs to be done for fuse and the circuit breaker. You can use a #6 copper wire for the purpose.
Testing and Power Up
All wiring should be checked thoroughly with a volt-ohm meter. Ensure there is no short connection and all the positive leads and negative leads are connected to their respective counterparts on the battery. Using multiple batteries often bring up the problem of voltage mismatch.
You have to check them out and see if the voltages are correct. After this you can turn on the power and get electricity flowing in your off grid solar power system.
If you want more in depth information on installing solar systems I recommend “Free Energy Options” which will discuss every type of power generation you’ll need. Check it out here.