On-Grid & Grid-tie Solar

Grid-tie

On-Grid Systems are solar pv systems that only generate power when the utility power grid is available. They must connect to the grid to function. They can send excess power generated back to the grid when you are overproducing so you credit it for later use.

Benefits: These are are simplest systems and the most cost effective to install. These systems will pay for themselves by offsetting utility bills in 3-8 yrs.

Downside: These do not provide power during a grid outage.

Off-Grid/Hybrid Solar

Definition: These systems allow you to store your solar power in batteries for use when the power grid goes down or if you are not on the grid. Hybrid systems provide power to offset the grid power whenever the sun is shining and will even send excess power to the grid for credit for later use.

Benefits: Provides power for your critical loads when the power grid is down.

Downside: Cannot be expected to provide power for all your loads since the cost and volume of batteries would be prohibitive. Off-Grid systems require a lot more specialized equipment to function that is more costly and more complex to install. Specifically they require a central/string inverter, a charge controller as well as a batteries.

Sizing the solar array and the batteries required is complex. Detailed analysis of your requirements will be needed to provide for your minimal critical needs. You’ll also need to rewire you main electrical panel to isolate the “critical loads” so that only they are provided power in an outage. This means that your well pump, refrigerator and a few lights are provided power while your air conditioners and TV and other non-essential loads are not.

This is definately more complex to install as well. There are dangerious components, mostly dealing with high amp batteries so caution needs to be exercised. Also, batteries are expensive, require ongoing maintenance and periodic replacement.

Given the additional specialized equipment required and the fact that it requires come complex installation, expect a off-grid system to cost four(4) times as much to install per watt and to require ongoing maintenance outlays.

Solar Pumps

Solar powered water pumps can deliver drinking water as well as water for livestock or irrigation purposes. Solar water pumps may be especially useful in small scale or community based irrigation, as large scale irrigation requires large volumes of water that in turn require a large solar PV array. As the water may only be required during some parts of the year, a large PV array would provide excess energy that is not necessarily required, thus making the system inefficient.

Solar PV water pumping systems are used for irrigation and drinking water. The majority of the pumps are fitted with a 2000 watt – 3,700 watt motor that receives energy from a 4,800 Wp PV array. The 5hp systems can deliver about 124,000 liters of water/day from a total of 50 meters set off head and 70 meters dynamic head. Energy storage in the form of water storage is better than energy storage in the form of batteries for solar water pumps because there is no intermediary transformation of one form of energy to another. The most common pump mechanics used are centrifugal pumps, multistage pumps, borehole pumps, and helical pumps. Important scientific concepts of fluid dynamics like pressure vs. head, pump heads, pump curves, system curves, and net suction head are really important for the successful deployment and design of solar powered pumps.

2.2Kw 380V met sonkrag

Solar water heating system heats water by using solar energy which is free of cost and while heating water no damage is caused in the environment. So it is one of the safe and efficient ways to deliver hot water.