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Choosing the right solar inverter

Updated: Jul 16, 2021

Solar inverters can be classified according to the following criteria and while selecting the most suitable inverter for your solar plant there are some key points to consider for best results , safety and longevity of the solar plant.Selecting the solar inverter depends on a variety of factors like type of rooftop , size of the plant ,fire safety and voltage levels,availibility of electricity, shading scenario ,financial viability , technical requirements such as power factor control , temperature and other environmental conditions.

1) Residential solar power plants :- These solar power systems are often 5kWp to 25 kWp in size and are primarily installed to mitigate electricity bills by the consumers. The prime factors on which inverter selection here is done are

(a) Fire Safety :- Prefer a low DC voltage system which are almost immune from fire hazard . In absence of regular maintenance conventional high voltage string inverters can be unsafe as these systems can catch fire owing to loose connections.

(b) No. of MPPTs (Maximum Power Point Tracker) :- Solar power plants based on string inverters are based on series connections between the solar panels. This means that shadow on even 1 panel can bring down the generation of the whole plant.Some times space available is not appropriate to put a certain capacity of panels and inherent problem of string inverters do not allow the solar panels to be installed in different orientations.

(c) Avoiding DC cables :- Direct current (DC) can be more dangerous to humans than the AC current. When we join them in series we do it using DC cables. DC cables can crack , insulation can get damaged and once it develops a fault it becomes really dangerous.

(d) Monitoring level :- Choose an inverter which in addition to solar generation monitoring could also monitor the grid. 360 degree monitoring from Heliumfour HeliumFour Solar can predict your monthly electricity bill . It measures and reports grid import , grid export , self consumption , Net export or import and self sufficiency.

(e) Solar panel level monitoring :-Residential solar power installations are small and performance of each module counts. Choose an inverter which could monitor the generation from each solar panel. This helps in getting most out of your plant.

HeliumFour's recommendation for residential solar systems

ENPHASE MICRO INVERTERS - Click Here to know more

Download PDF • 286KB

2) Commercial/Industrial solar power plants on metal roof :-

Commercial solar power plants are in the range of 25 kWp to 1000 kWp and sometimes even larger. Industrial tin sheds have in recent times been very popular to install solar power plants as they offer best highest energy density /cost ratio when compared to ground mounted or RCC roof mounted solar power systems. When selecting a solar inverter for Metal Shed Installations following must be taken in to consideration.

(a) No of MPPTs (Maximum Power Point Tracker):- Carefully analyse the site for shadows and see how many MPPTs are required . Metal sheds can have different orientations so plan accordingly . Remember if a single MPPT is used on panels with different orientations or with partial shadows it can ruin the energy production of the system.

(b) Power Factor control :- If a solar inverter can be used to improve the power factor of the site it must be used . Monetary speaking all solar production would give benefit to the owner only when the power factor is close to 1.

For detailed article on how solar plants can control and improve power factor click here

HeliumFour's recommendation for commercial solar systems on Metal roofs

SMA , Germany Core 2 solar inverter 110 kW capacity Click Here to know more

Download PDF • 456KB

3) Commercial/Industrial solar power plants on ground or RCC roof:-

In addition to selection criteria which is relevant above for C&I solar power plants with capacity 50 kWp to 500 kWp following must be considered.

(a) Minimising the DC cable length :- These plants have a lower ground coverage ratio when compared to Metal roof mounted plants. This can increase the length of DC cables which will lead to higher losses and are also prone to damage and catching fire . Smaller inverters , about 25 kWp each should be used in such solar plants.

HeliumFour's recommendation for commercial solar systems on RCC roofs & ground

SMA , Germany STP 25000 solar inverter 25 kW capacity Click Here to know more

Download PDF • 600KB


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