Debunking myths about orientation and sizing of PV systems – pv magazine International

New research from Lappeenranta University of Technology shows that there is no one correct orientation for a PV installation.

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Researchers from Lappeenranta University of Technology (LUT) claims to have debunked three myths about orientation and sizing of PV systems and the sale of excess electricity.

“The results are applicable to conditions in the north, but the methods are applicable anywhere,” said a spokesperson for LUT. photo magazine. “Our experts would like to take a closer look at other data and data from other countries regarding solar electricity, energy consumption and electricity prices.”

In a first study – “Optimization of rooftop PV installations to maximize revenue in Finland based on customer class load profiles and simulated generation,” Posted in Solar energy – the scientists considered a direction of the PV system based on profitability. They used hourly data from 13 different statistical customer class load profiles, historical electricity market price data for the period 2016-2020, and a simulation of solar PV yield from southern Finland.

The research group compared single-azimuth and double-azimuth systems. He found that the first project typology was more cost effective under a net metering regime, with optimal orientations being identified at azimuth angles of -15 degrees to -5 degrees and tilt angles of 35 degrees to – 45 degrees.

“However, if no compensation is paid for the excess electricity, it is usually more cost effective to minimize the purchase of electricity by orienting the solar photovoltaic modules in two azimuths between east and west with angles d tilt from 10 degrees to -55 degrees, depending on the capacity of the solar PV system and load profile,” they said.

An east-west orientation could lead to financial losses of 15% compared to a south-facing system, when net metering is not in place and self-consumption must be maximized.

“A southern orientation is economically viable whatever the consumption profile. There is no one correct orientation. The choice depends on whether you want to maximize self-sufficiency in power generation or profitability,” said Altti Meriläinen, research assistant in electrical engineering at LUT University.

Optimal sizing

In “Optimal sizing of a photovoltaic solar power plant with electrical load curves measured in Finlandwhich was recently published in Solar energy, another research team studied the profitability of PV systems for self-consumption. They focused on a grocery store, a dairy farm, and a house in southern Finland.

“The profitability of the photovoltaic power system was studied using the internal interest rate, net present value, discounted payback period and self-consumption rate,” the researchers said.

They found that the respective internal rates of return were 6.8%, 6.6% and 1.4% for groceries, dairy farm and home. For the grocery and dairy farm, the size of the PV system could be increased without the internal rate of return decreasing significantly, which would justify a larger installation. On the other hand, using the self-consumption rate to optimize the size of the PV power system could result in an undersized system.

“In single-family homes, the best or most cost-effective solution is to oversize the solar PV system. In large buildings, 100% self-consumption is the most economical alternative. On the other hand, profitability would not fall due to excess return,” said researcher Antti Kosonen.

A paper in Energy appliedTechno-economic viability of energy storage concepts combined with a residential solar photovoltaic system: a case study in Finlandcompared the profitability of photovoltaic systems operating under net metering with that of solar panels connected to physical or virtual storage. The researchers found that selling excess electricity to the grid would be the most cost effective option.

“(The) addition of physical battery energy storage to the energy system was found to increase self-sufficiency by 20 to 30 percentage points for the homes in the study,” the academics said. “It was observed that the maximum power capacity of the solar photovoltaic installation was an important factor in determining the amount of increase in self-sufficiency obtained by the use of an energy storage battery, the increase being higher for large solar photovoltaic installations.”

But given the current electricity price scenario in Finland, the deployment of lithium-ion batteries for residential applications is not yet economically feasible, they concluded.

“An increase in the price of importing electricity, of which the transmission price is the most important and likely to increase, would improve the profitability of an investment in physical battery storage,” they said.

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