The moment you go off-grid, you rely entirely on a system that generates electrical energy and utilizes the same to support all your electrical appliances, either at home or on a business premise. For your system to be exclusively off-grid, it must have absolutely no link to the utility grid.
Going off-grid is possible, practical and beneficial to you in many ways. You will not have to pay utility bills and in the long run, you will save money! Other motivations include: environmental concerns and endeavoring to only use renewable energy; energy independence, you won’t have to rely on the blackout-prone utility; social values, which mean taking responsibility for your energy consumption effects; costs, when the distance to the grid is too big, your decision to go off grid becomes a lot cheaper.
So, if you either live far from the grid or in places with no electric connection, you have no choice except to go off-grid. Ultimately, you must find out the cost of making the connection as well as what the cost will cover, before making an informed decision whether to go off-grid or not.
Considerations Before Going Off-Grid
1. What’s the cost?
Price plays a crucial role in your decision to go off-grid. Could you afford the cost of installing an off-grid system? If you’re planning to live in the location long enough, going off-grid is reasonable because you will adequately recover the costs you incur setting up your power system.
2. How much electric energy can you obtain from the available surface?
Do you intend to go off-grid and still maintain your current energy consumption rate? If your answer is yes, you’ll have to purchase sufficient energy harnessing and storage capacity. For homes occupying a quarter acre plot, the rooftop does not offer enough space to install sufficient PV panels. If you don’t have enough roof space either; buy high-efficiency PV panels, or you can reduce your power consumption, so that the power you can obtain from your roof space is adequate.
3. Will you have an increase in electric power needs in the future?
In any household; power consumption varies from time to time. Every time you add high-energy consuming appliances, the power consumption spikes. Put such factors into consideration while planning to go off-grid.
4. Battery security requirements.
Install, operate and maintain your batteries using expertly recommended procedures to eliminate risks. So, find out your battery safety requirements from the manufacturers. Also, avoid shortcuts while installing and maintaining your storage system, for your safety.
5. Care and maintenance
Consider the cost of maintaining your off-grid system. Solar panels can come with a 25-year maintenance warranty. You will need to replace batteries and inverters somewhere between five and ten years.
1. PV Panels
The larger the size of the PV panel you are using, the higher the amount of electricity it generates. Weather conditions of your locality also play a role. So, you need to factor in Photovoltaic Generation Factor (PGF), which considers both the panel size and prevailing climatic conditions (refer to the attached map for PGF of your particular state). Use your area’s PGF to size your PV panels as follows:
Calculate daily wattage-Hour (WH) needed from PV panels by multiplying the sum of daily devices (WH) by 1.3 to obtain the total WH you require daily. 1.3 takes care of the energy you will lose while converting energy from one form to another as well as any copper losses.
Divide the result by PGF to get WH ratings of the solar panels required to support all your devices.
Divide the result by rated Watt-Peak output your PV panels can generate. Raise any decimal number to the next higher full number (for instance 4.23 to 5). The figure you obtain gives the number of panels you should use.
For example, The sum of daily devices WH is 2000kWh, the PGF of your state is 4, the total WH you require daily will be 2000*1,3/4 = 650 Watt-Peak. If your PV watt-peak is 200, then you will need: 650/200 = 3.25 or 4 PV Panels.
Since power factor is practically less than 1 (varies from 0.85 to 0.99), take 1.18 VA to be equal to 1 W. If your total Watt-Hours is, for example, 1000, multiply the figure 1000 by 1.18 to obtain 1180 VA (or 1.18 kVA) as your inverter size. Make a habit of adding some extra to be on the safe side. As a result, acquire an inverter whose rating is slightly higher than the figure you obtained.
Size Your Battery As Follows
- Divide your Watt-Hour by 0.85 to take care of battery losses
- Divide the answer by 0.6 for the depth of charge
- Divide your answer by minimum battery voltage
- Multiply your answer by days of autonomy (the days you will use your system, yet PV panels aren’t generating energy) to obtain the AH (Ampere-Hour) of your deep-cycle battery.
Multiply the PV panels you require by WH (Watts-Hour) to get the total power your system will generate. Divide what you get by your battery bank’s voltage to get the current flow at any given time. Raise this current value by 25 percent to account for low temperatures before rounding it up to the next whole number. What you end up with is the controller size suitable for your system.
If you are planning to use an off-grid system, note that it’ll solely rely on the energy it generates. However, the fact that the sun rays vary from time to time, present you with a significant challenge. To design such a system in such a way that it overcomes the variations, you must spend a lot of money because you will have to use high electricity generating capacity coupled with a massive storage capacity. Your resulting system will, however, be efficient and more environmentally friendly.
To maintain your batteries, add water whenever the level of the electrolyte decreases below the electrodes, clean the terminals (using distilled water) and check connections as often as possible. Also, set up a proper charging routine for your batteries to last longer. Never leave your batteries in the uncharged state for an extended period.
If you live in an area that experiences unbalanced resources, you will require a fuel-powered quiet generator for home backup purposes. Nonetheless, you still need to invest in a modest home backup unit; to support crucial appliances during periods of emergencies.
Which is the best option: hiring a professional to design your off-grid system or installing it yourself? The former requires first establishing if the professional you are considering has ever installed an off-grid system. The latter requires attending classes so as to acquire the necessary skills and purchasing components from a reliable vendor (preferably local). Provided you are sure an off-grid system is best for you, do not take chances. Make sure your system is installed correctly and enjoy the independence of using renewable energy.
About the author: Victor Hill, an expert in generators who writes for and owns Trustworthy Power. He has a degree in Mechatronics, reviews the various types of generators, provides users with guidelines on how to choose, care for and use generators. He is a Quality Assurance Engineer at DENSO but spends his free time researching about generators and coming up with helpful information for users.
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