Off grid Solar Systems



If your home or ranch is located far away from the nearest power lines (the "grid"), off grid solar systems can provide you with a reliable, clean and silent power generation solution. The heart of these off grid solar systems are the solar panels. Solar electric panels have no moving parts (therefore reliable), they are silent, they do not pollute and they enjoy a long life span. Other cost effective off grid power generation systems are dam-less micro-hydro systems and residential power wind turbines.

click to jump ahead to the off grid solar systems Technical Overview Section

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click here to view other other types of off grid power systems

The "grid" and the meaning of off-grid

“The grid” is a colloquial name to the immense infrastructure the electrical utility companies have in place. Most home users have access to the “grid” and once they sign the contract with the utility company the utility connect wires to their home, meters the home consumption and start to send the monthly bills.

Whether you plan an off-grid installation or an on-grid installation view my solar power checklist page

Overview of off grid Solar Systems

The generator of the solar power system (or the engine) has no moving parts and it is silent. The generator is an array of solar panels. Solar panels are converting sun light radiation directly to DC electrical power, taking advantage of the photoelectric effect.
Since electricity is needed around the clock and the sun (what delivers power to the panels) is available only during daylight, some way to store electricity during the day to be used over night is a necessity. The most ubiquitous electricity storage is the battery (more like the battery you have in your car but don't use car batteries). The third element is the off-grid inverter. The inverter inverts the DC electricity from the battery into more useful AC electricity (115V, 60 Hz in the US). One more necessary element is the charge controller that protects the array of batteries from overcharge. Some vendors will integrate the charge controller into the offgrid solar inverter.

off-grid-solar-system

The picture describes how off grid solar systems are wired. In next paragraph I’ll describe how to size the different elements. Although in the drawing you see only one battery, in practice you need many batteries to store enough electricity for your night consumption. Except for the batteries, the other elements don’t require much maintenance effort and exhibit an inherent long life. Make sure you have good grounding to the different elements. Also make sure the outdoor parts are protected from lightning storms (the lightning in rural areas “seeks” tall objects and the solar panels on the roof is an “ideal” object for it…). If you bring a contractor, he is licensed to run electricity lines. If you do it yourself bring in a licensed electrician to do the electrical installation and don’t risk your life. There is no utility that will make the safety checks for stand alone off grid solar systems. It is up to the homeowner to check for the safety of off grid solar systems

Sizing off grid solar systems

View my page sizing the off grid power system. Correct sizing is of utmost importance. If the size is too small there will not be enough electricity. If it is too big, it is a waste of money

Most on-line stores and off-line stores for solar products can provide you with assistance, calculators and other support.

A good contractor, worth his reputation can give you a technical proposal and a price quotation for a turn key job.
With the solar contractor proposal you will have a baseline with which you can further evaluate the off grid solar cost to you.

The components of Off Grid Solar Systems

These are the components of the off grid solar power generator:

  • solar panels sized to fit the home consumption
  • Batteries; deep cycle batteries (not car batteries), can be charged and discharged many times, as many as required. Install the batteries in a ventilated space and not in a living area, not exposed to extreme hot/cold temperature and with good maintenance access. The life expectancy is 5-15 years(much shorter than the other elements’ life expectancy)
  • Charge controller
  • A pure sine wave inverter
  • Grounding, surge protector, circuit breakers and other safety and protection devices
  • Optional and highly desired: a good smart display to see the performance and status of the different parts
  • Try to use the shortest and a higher gauge DC lines to reduce losses on the lines.

Good off grid inverters include a charge controller, smart monitoring and smart controlling of an external backup diesel generator. It is wise to choose carefully the off grid inverter, it is justified to pay a bit more.

Cost, tax credits and solar energy loans for offgrid solar power systems

If you live or plan to live off-grid, your first option is to connect to the grid and pay the utility upfront $15,000 to $50,000 per mile and pay the electricity bills once you are connected. The advantage is that you have a reliable source of electricity. You can reduce the required solar generator size and cost by choosing carefully your off grid electrical appliances

Your other options are wind electricity, a dam-less microhydro generator and a diesel generator. For wind turbine you still need battery backup. For a diesel generator you need to transport and store expensive fuel. Microhydro systems are extremely cost effective, however you need to have a water stream that can be harnessed on your site.

A typical cost for offgrid solar power system (equipment only not including installation) that includes 2,000W solar panels array (can supply 300KWh per month), batteries with 20KWh capacity, an inverter, a charge protector and an installation kit can cost $22,000-25,000. To this you need to add installation cost (unless you build it yourself).

However you can rebate 30% on equipment and installation cost on federal tax credits and additional tax rebates in some of the states. Subsidized financing is available in some states.

Maintenance Cost

Maintenance cost is low for the system; however you need to expect replacing batteries every 5-8 years. A set of new batteries might cost you $2,500

Your annual saving on electricity bills is 300KWh per month multiplied by 12 and multiplied by the price the utility charges per KWh (you can assume 20 pennies per KWh, it is dependent in which state is your home). it equates to $720 every year.

If you need a bigger system you can scale up above numbers. You can calculate whether the investment worth it, taking into account the net investment, interest rate, solar system life time of at least 20 years and the accumulated savings on electricity bills. You also save the one time connection to the grid fee, that in many cases is more expensive than the solar system.

click to view what is the "grid"


Other Off Grid Power Generators

Offgrid solar power systems are residential photovoltaic electricity generators not connected to the utility power lines; many off grid homes also use off grid wind turbines and microhydro turbines to generate electrical power.
Geothermal off-grid power is an interesting option, view this link, Geothermal Energy - What is it and how does it work?

Homes and ranches that are far away from where the edge of the grid reaches (off grid homes), may consider the option to produce their own off grid power. They install a small photovoltaic "power plant", a wind turbine or a water turbine to supply their needs. Since these “power plants” are not connected to the grid this arrangement is called off grid power generator. Utilities charge anywhere between $15,000 to $50,000 per mile to run a new power line to an off grid home. This amount can pay most of the needed money that is needed to buy and install the off grid power system.

A neat solution for pumping and handling water in remote areas are solar powered water pumps

As any other power plant the off grid power system must have a generator. It could be a diesel generator, it could be a offgrid wind generator, it could be an offgrid solar power system. It could be a water turbine and it could be a combination of 2 or 3 energy sources (sun, wind and water). The combination that makes sense is a hybrid solar wind off grid power system. Each is a backup to the other and both can use shared components such as the DC to AC wind/solar inverter and the storage deep cycle batteries.

It is therefore advisable to install both off grid photovoltaic (solar) system and a small wind turbine, because these two systems are complementary and they can share expensive resources (e.g. the batteries)


A short video

I invite you to view this video on off grid solar systems. It shows the way this system is built. It shows specific products, however make your own market research. In particular, avoid using deep cycle batteries that need adding distilled water, use sealed batteries instead






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