Practical Considerations When Using Solar Power

1. Light Variation.

Cloudy days vs too hot days. On cloudy days the power produced will be small because light is converted to electricity. The power produced by a given number of solar panels is more in summer and less in winter (for most of South India). The power consumed is more in summer and less in winter (again for most of South India).

2. Switching.

Ability to turn on and off all devices. Designing the solar power system for peak capacity is not economical, because during off peak loads the power produced would be wasted. The optimum installed capacity would be the average of peak load and off peak load.

Some degree of inconvenience will be created to you, in turning off some appliances to be able to turn on some appliances. An example would be that you have to turn off the A/C to be able to turn on the motor pump. Once the room is cooled, turn off the AC and turn on the pump.

3. Overload considerations.

All inverters come with an audible indicator whenever there is overload. This is an existing feature in all UPS systems (battery & inverter set), that charge from the grid.

4. Output Considerations.

Connect a watt-meter in the wires from the solar panel to inverter. This allows you to monitor the efficiency of the solar power system and detect any problems before a system failure occurs.

5. What devices work?

Almost all lights, fans, electronics, refrigerator, TV etc.. (for a 4 BHK house with 1 KVA solar power generation).

6. What devices do not work?

Geysers. Surge pumps. Air Compressors. Air conditioners. They do not work mainly because of the high surge current upon turning on the appliance. Surge current is a steep increase in the electric current flowing in to the circuit/load up on starting the appliance.

7. Mounting Considerations.

Mount at 30% inclination for reasonable cooling and maximum efficiency. Solar panel efficiency is the ratio of electric power output by light energy input. Solar panel efficiencies range from 12% to 20%. Their efficiency drops with increase in temperature. This is a minor concern. It does not affect the life or efficiency of the solar system noticeably. Also under absence of load, the unused power does not turn into excess heat.

It is important to mount the solar panels on to a wooden or aluminum frame, then mount the aluminum frame to the roof or wall. This is because geological weather conditions change slowly over time and also a tall building might pop up right next to your house and you would have to move the solar panels to get more sunlight.

Take a look at the picture below this what i am thinking for my home.Looks simple and can be easily moved without lot of damage to the floor.



8. Maintenance Considerations.

As is, regular maintenance is not required and is NOT a must. However regular maintenance once in every 3 months would increase the performance of the system.
Some recommended maintenance considerations are to clean the top of solar panels of any mud or dust, check the voltage output from panels, battery & inverter and check the power output from the inverter.

9. Battery Considerations.

SLA battery a.k.a Tubular battery.

SLA battery stands for sealed lead acid battery. They do not require frequent recycling of the battery fluid and do not expose lead. They are specifically designed for renewable energy power generations that rely heavily on storing generated power to the battery and frequent discharging of the battery.
Also set the battery threshold at the inverter at 50%. This way, you will get maximum life on the battery.

Please keep the battery on wooden or bakelite enclosures only. Batteries do dissipate heat and in the event of short circuit, wooden or bakelite enclosure would prevent batteries discharging to the ground and posing a life hazard.

10. UPS battery Vs Deep cycle Battery

UPS battery and deep cycle battery work on the same principle. The similarity ends there. Deep cycle battery is designed to provide steady amount of current for long periods of time. UPS battery is designed to provide large amount of current for a small duration.

11. Why Deep Cycle Battery?

Can UPS battery be used instead of deep cycle battery?

Please DO NOT. You can get away with doing so. But your battery will die in less than 2 years.
To explain the reason in layman's terms, use an axe to cut the tree and a shovel to dig the ground. To explain the same in technical terms, Deep cycle batteries have thicker electrodes and lead plates, that can withstand long periods of discharge. On the other hand, UPS battery will die soon, if discharged for long periods. Click here to watch an you tube video on deep cycle battery. Click here to see a very good explanation from a professional on deep cycle battery.

12. Battery Capacity Considerations.

    A battery's life is rated in cycles. 300 cycles means the battery can be charged and discharged 300 times before there is a drop in stored capacity. SLA batteries are rated in DOD & cycles. DOD stands for depth of discharge. A typical life rating of SLA battery would be 500 cycles at 50% DOD.

    The drawback of SLA Battery is that its stored capacity should not be less than 50%. Each SLA battery has a rating, some 50% and some 70%.

    Discharging the battery to below 50% of the capacity reduces 1 rated lifecycle of the battery. This is the significant drawback of using the battery. Please click here to see a more detailed explanation of deep cycle battery.

     Click this site to see a good energy vs efficiency calculation.



Note here that if the battery is used to full 100% every day it will last only 300 cycles i.e. less than 1 year. If it is discharged to 50% then it will last 2.5 years at full capacity and an other year at 70% of the capacity.

This section is a continuation of my main blog. Please click here to read my main blog.

No comments :

Post a Comment