Off grid solar electricity for home & business

The big benefit with off grid solar is once it’s installed, electricity will be free for the next 40 years or so.

Though it costs more to set up a totally stand alone solar power system, the money you save in the long run is definitely worth it.

If you do the math, it becomes clear that off grid solar power makes a lot of sense if you have the initial bucks, want to be completely independent of the grid, and especially for remote location applications.

The PWM company cover everything you need to install solar powered system.

  1. Determining how much power you will need
  2. Calculating the amount of battery storage required
  3. Calculating the number of solar panels needed for your location
  4. Identifying a solar charge controller
  5. Selecting an Inverter
  6. Balance of System (BoS)

Our off-grid solar packages come with everything you need to build your own personal power plant, right on your property. You’re in control – no more monthly bills and no utility company to answer to. Just 100% clean, renewable energy from a system you designed yourself.
Off-grid solar electricity is for homes that do not have access to grid electricity – i.e the house cannot be or chooses not to be supplied electricity from a power company. These systems offer complete autonomy and independence from the national grid and power companies, meaning you never have an electricity bill.

 

  1. Solar PV panels mounted on your roof or near your house capture energy from the sun and convert this energy into DC electricity
  2. A Solar Inverter converts this DC electricity into 230V AC electricity.
  3. The main switchboard takes electricity from the solar inverter or battery inverter and sends it to power your home.
  4. The battery inverter is two way and can take surplus electricity from the main switchboard and convert in into DC electricity to be stored in batteries or demand is their convert stored DC electricity from the batteries into AC electricity to power your house.

In off-grid homes (i.e. homes not connected to mains electricity), small-scale wind turbines and photovoltaic (PV) solar panels can be a good alternative to either grid connection (which can be expensive) or a diesel generator (which wil be noisy and polluting, and have ongoing fuel costs).

What does it mean to go “off the grid”?

Installing solar panels on your roof doesn’t mean that you’re off the grid. Most solar systems can’t consistently generate enough electricity to be a home’s only power source, which is why the vast majority of solar homeowners maintain a connection with their utility company. When you generate more power than you use, your utility gives you a net metering credit on your electricity bill. When you need to, you can then spend your credits to supplement your solar power with electricity from your utility company. If/when you don’t have credits, you’re simply charged the going rate for electricity at that time. For the average solar homeowner, this process typically means you’re generating more power than needed during daylight hours, and less than needed at night.

If your solar panels can generate over 100% of your home’s electricity needs, then the credits you receive from your excess power generation could theoretically cover the costs of electricity needed in low-sunlight periods. However, this process requires that your home still stay connected to the grid. By truly going “off the grid”, you would need to sever your connection to your utility company. By doing this, you would lose the ability to purchase electricity from your utility in low-sunlight periods. This is why your home would need solar batteries installed to stay powered at night.

If you’re off-grid and need power all year round, wind and solar complement each other well as there is more wind in winter and more sun in summer. If you just need power in summer (e.g. in a caravan), you may want to use only solar power.

Considerations for siting a wind turbine or photovoltaic panels are the same as with grid-connected systems – an unshaded and roughly south-facing site for solar, and somewhere with a strong, consistent wind speed for a turbine. For more advice on assessing a site, see our pages on wind power and solar photovoltaics.

Solar off-grid inverters

In order to convert the direct current (DC) collected by your solar panel array into the alternating current (AC) required to run most of your common household appliances and electronics, your solar power system will also need a solar inverter – sometimes referred to as a solar converter or a PV inverter. For the purposes of an off-grid system, you will likely use a stand-alone inverter, though there are a few options when it comes to set-up.

For many people, powering their homes or small businesses using a small renewable energy system that is not connected to the electricity grid – called a stand-alone system – makes economic sense and appeals to their environmental values.

Successful stand-alone systems generally take advantage of a combination of techniques and technologies to generate reliable power, reduce costs, and minimize inconvenience. Some of these strategies include using fossil fuel or renewable hybrid systems and reducing the amount of electricity required to meet your needs.

Solar panels array mounting

Most off-grid solar systems will have their panels mounted on a roof or on a pole. Both configurations have their advantages and disadvantages but work equally well when installed properly. Regardless of which method you choose, your solar panels must be mounted securely. Follow the assembly instructions for whichever type of mount you have selected. From an electrical standpoint, there’s really not much difference between a roof-mounted system and a pole-mounted system. But if you use a pole mount, you will need to get the power from the solar panels to your house. This is normally accomplished by digging a trench between the pole location and the part of your house where you want the electrical wires to enter the building.

A roof-mounted system will also use a combiner box. It serves the same function as it does on a pole-mounted system. However, it can sometimes be a little more tricky or difficult to run wires from the roof’s combiner box to the charge controller, especially if it’s being installed on an existing house. The best time to run electrical conduit and wires is when the house is being built. This is one reason why a pole mount system can sometimes be easier to install for existing homes; the electricity can usually be piped into the house directly into the equipment room. Installing a roof-mounted system in an existing home is certainly possible if you have the proper tools. Most large solar panels now come with the negative (-) and positive (+) wire leads already connected to the junction box.

If you are using a pole mount, you will also need to install an eight-foot copper ground rod at the pole location. If you live in a very dry or desert-like environment or have very sandy and rocky soil, you may need to install two or three ground rods and connect them together for a better Earth connection. Ground rods must be driven vertically into the ground whenever possible. If rocks or other obstructions are preventing the rod from penetrating the ground vertically, the NEC does allow for the ground rod to be driven in at a 45-degree angle or even laying flat in a trench. A vertically-driven ground rod is always best whenever possible. A sledgehammer is often required for driving the rods into the ground. If you own a jackhammer, you can find a bit attachment for driving ground rods that makes the job much easier. The ground rod(s) at the pole mount needs to be connected to both the combiner box ground bar (more on that later) and to the copper ground rod for your house. The house ground rod and the pole’s ground rods must be connected so that you do not have two isolated grounding systems connected to the same electrical system. There are lots of technical and scientific reasons as to why the ground rods need to be connected together, but that’s not the focus of this article. Just take our word for it and you’ll save yourself a lot of frustration. The easiest way to do this is to lay a bare copper ground wire in the same trench as your conduit. Do not run the bare wire inside of the conduit. You will get a better Earth ground connection if you run the bare copper wire directly in the trench, next to your conduit. The pole mount array will normally consist of the mounting hardware, solar modules, wiring, and a combiner box with circuit breakers or fuses. A basic combiner box has more than one function. It combines the output power of multiple solar panel strings and it’s also a transition point where the smaller gauge wire from the solar panels can be increased in size, if necessary. The distance from the pole mount to your solar charge controller, along with the array amperage, will determine what size wire you will need. If you purchased your system from us, we probably already informed you of which size wire to use. If you purchase your equipment from us, our system designers will be happy to calculate the wire size that you need.

MPPT charge controller – the bridge between solar panels, battery bank & inverter

The PWM company charge controllers allow for a wide range of voltage inputs, which will directly affect how your solar modules must be connected and wired. Always pay attention to the voltage ratings of your equipment so that you do not inadvertently use too much or too little voltage. The proper solar panel voltage should be determined during the design phase, based on the equipment you will be using.

Some MPPT controllers can be sized well above the maximum operating output power rating without damaging the controller or having the charging current exceed the maximum output current rating of the controller. This means that array oversizing with off-grid systems can result in a positive return on investment, similar to the results commonly achieved with grid-tied inverter systems.

 

MPPT controller maximum nominal operating power depends on the rated charge current and the nominal system voltage. During the middle of a sunny day, there may be more power than the controller can use with an oversized array. However, an oversized array will often contribute more power than a smaller array in the early morning and late afternoon, or even during the middle of a cloudy day. Excessive oversizing of the array may show a diminishing return if the power limiting is more significant.

Some of the benefits of exceeding the nominal wattage ratings of an MPPT controller include:

  • Daily maximum power levels can be much lower than the STC rated power of the solar array. Tilt, azimuth angle, time of day/year, weather, climate, dust and other factors reduce output power from the array leaving unused controller capacity
  • Full charging potential of the MPPT controller can be used more often
  • Better production early and late in the day
  • Better production during cloudy weather
  • On sunny days, excess power is not needed once the batteries are close to full
  • Reduced maximum charge current for smaller battery banks
  • More string-sizing options with higher power arrays

In addition to STC power, array voltage needs to be considered. The minimum Vmp should stay above the battery maximum Vb for consistent charging to occur, and the array Voc should never exceed the maximum voltage ratings of the controller. A string sizing calculator can provide minimum and maximum voltage levels for an array based on record low temperature and maximum average high temperature.

Operation at full power with sustained high temperatures may cause unnecessary stress on the controller’s electronic components. If oversizing is considered in hot climates, the TriStar MPPT controller can be programmed with a reduced maximum battery current limit so the controller will not get overheated as often.

Conclusion

Off grid solar energy offers high tech and efficient solutions, bringing electricity to remote rural villages, with no need for huge electrical grids and unsustainable costs for governments or local communities. We can bring energy to rural and remote villages, we can create local grids with a bigger shared solar power station or a single solar kit bringing power to single households or businesses. We design solar water pumps or batteries to accumulate energy from the sun and from traditional power generators at the same time. Thanks to the sun we even create mobile off grid living spaces, like classrooms or Internet points, micro clinics or bars.