10/06/2020
Grid tied vs Off-grid solar power generator system
Well, with Solar power generator systems (PV) becoming a trend it is worth to get a better picture of what is available on the market today. It may save you $$$ by opting for the right design from start.
The Basics:
A solar power generator includes Photovoltaic cells arranged in panels,
1. PV panel the first link to convert solar visible light energy to electrical energy. Two major types of PV cells are available: silicon or perovskites, the latest being more efficient at a premium. The PV cells are embedded together to form a panel which generate a higher power, the more cells per panel the more power generated. The quality of the panel assembly is an important factor when buying, a cheap workmanship and poor materials will yield to degradation in no time while a quality panel will last 10 to 20 years. PV panel size is only an installation design issue as generated power is strictly dictated by the surface of the panel(s) with its quantity of cells and cell efficiency. The most efficient cells in a panel of x surface resulting in more generated power than the same panel size with less efficient cheaper cells.... when it comes to installing the generation solar plant, available roof footprint should have been taken into consideration at design stage. You can put only so many panels on one roof!
2. Controller/inverter. The PV panel(s) electrical output is DC with voltage ranging from few volts to 300 Volts or more depending the number of of cells and their wiring configuration. Ditto for the available dc current generated, from few mA to 10-20A or more also based on the panels wiring configuration. Free DC power from the sun is great but not very practical to power house home appliances! And of top of that voltage/current will vary depending the sun light Intensity! So we call in a magic black box to convert this DC power into AC 220V50 Hz compatible for your equipment like fridges, TVs, washing machines, A/C and so on. The controller manages the available DC power coming from the PV panel plant to generate a stable AC power regardless the sun intensity is low or strong. However when the sun light intensity is too low like after sunset to sunrise it shuts down, no more power and it all goes dark...till next dawn.
Grid tied systems
The controller is connected to incoming mains (grid). The Solar power generator supplies the power for your home requirement. When the Solar power generation is greater than your electrical consumption the extra generated power is re-injected to the grid, depending the country where you live and prior arrangement with your Electric Service Provider you may get get a refund for the prorata of KWh you generated and donated! But It’s most likely less than the cost of KWh you buy. That works fine to some limitations. Night time, as there is no sun light your controller automatically switches to grid for your appliances, at a higher price you undersold your power before! Secondly, if the grid is off ( blackout) it’s time to pull the candles out of the drawer.... Oops! Forgot to mention too that on sunless overcast days your solar system won’t be generating so you are back to square 1 sucking from the grid if no blackout at top price. Seems your investment in a grid tied system is not after all so impressive, you’re still tied and depending on Big Brother.
Off-grid systems
Similar system as above with the addition of power storage when you need it most.
• The controller while giving your full power requirements during the day when sunlight is available also charges a battery bank. At night time or during blackouts you are still enjoying watching your TV in an cold room. You do do not longer rely on your Electric Service Provider, in fact you can disconnect them. You are self dependent, free. But freedom as a price, battery storage is the most expensive part but sized correctly based on your requirements every single $ of your investment pays off unlike a grid tied system. But if improperly designed you’ll end up with a more expensive product than a grid tied system, trust your service provider!
The Alternative Hybrid systems
We have seen the pro-cons of both systems above, cheap grid tied or off grid systems.
An alternative is to employ a second or third optional source of power generation. Windmill generator is an excellent option as supplement to sun power generation depending your geographical location. Wind blows days and night! A small windmill generator installation will reduce your battery bank capacity requirements as it will provide proportionally your power needs during nighttime while charging your batteries too if designed accordingly so you end up with more backup power autonomy when there is no sun.
Thirdly the controller can also be powered up with an electric power generator for real emergencies or last option the grid!
Sun tracking systems
Solar panels are cool! They generate electricity from the sun, that’s right.....
As we all learnt at school the earth rotates around itself and around the sun too! For flat earth believers this wouldn’t be an issue but as the earth rotates dictating the sun position from sunrise to sunset the PV panels would receive light at different angle of incidence during the day if they were fixed in a solid position. PV panel efficiency is maximum when the angle of incidence is within +/- 30o of the perpendicular plane. As the resulting sun trajectory is 180o from sunrise to sunset East to West it is easy to understand that the efficiency of the PV panel will be a couple of hours before-after zenith (noon). Winter/Summer solstices, as the earth rotates around the sun in an inclined elliptical orbit the sun appears rising from East towards West either on the Northern side or Southern side If you live in low latitude countries ( close to the equator), that translates for a fixed panel installation to a half efficiency generation depending if the panels are facing Zenith North or South...
The solution is to track the sun a bit like a radar tracking a target. Two axis tracking (East-West, North-South) will improve your power generation by 30 to 40% compared to fixed installation which is quite significant. You are going to spend $$$ on a 5KWh solar generator system, cool but you’ll only get 3.5KWh at most if fixed panels.... a bit of a waste of hard earned $. Same system with two axis tracking will give you all your dollars worth, 5 KWh. Ok, a two axis tracking module will increase the original investment but at 30% R.0.I per extra KWh this is easy math....
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We are a Service Provider, starting from client requirement evaluation, solutions, sourcing, installation, commissioning, training, and after-sales services.
Yes, you will find something that looks like our offer cheaper!!!
The difference is we have the experience, we design, build, Integrate our own systems.
We have been in business over 18 years and we breathe, we feed on customer satisfaction.
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