Questions Answers - Photo Voltaic Training Session 1

PV TRAINING – DESIGN, CONSTRUCTION, OPERATION AND MAINTENANCE

Q&A SESSION 1 September – October 2010 http://www.leonardo-energy.org/node/5948

If

the

northern

You will lose efficiency in tour system, but if

hemisphere, solar panels will be

the deviation is small, the losses will not be

mounted facing to south side with

very important. As an example, you can see

latitude(optimum)

the

degrees,

location

What

is

in

angle+/-15 happens

to

graph

in

the

slide

35

webinar

1,

the

(applicable in southern Europa):.If you take

output if panels are mounted other

an ideal panel tilt, deviations in orientation

than south side?

around +/-25 º are not very important

What are the methods which can be

Recommendations: 1. You can use thin film

followed to reduce the PV panel

modules

temperature

the

compared to the crystalline panels. (Losses:

be

Thin film 2 % each 10 º. Crystaline: 4 %/10

temperature

so

that

losses

can

reduced?

halving

the

thermal

losses

º), but you will need more land surface because his efficiency is lower/2. Keep a reasonable distance between panel and roof 3. If it is possible, avoid valleys and choose

Do you think about the precision of

locations with high altitude The meter has not influence in the PR, but it

de

is very important to have an accurate meter

meter?

Do

you

think

that

improve the precision meter you

to avoid slipping kWh away

can boost the PR? How are panels

You need link all the frames, an then

connected

for

earthing?

connect the ground cable to the structure of

Is 1460 KWH per year/ per month or

the building earthing system It is 1460 kWh per year and per kWp

per day? What is kW peak?

The maximum rated output of a photovoltaic device, such as a solar cell or array, under standardized test conditions, usually 1000 watts per square meter (0.645 watts per square

inch)

of

sunlight

with

other

conditions, such as temperature specified. Typical rating conditions are 68°F (20°C), ambient air temperature, and 1 m/s (6.2 x Is suntracker always justifiable? 2.

10-3 miles/sec.) wind speed You can find trackers with prices around

What is the normal increase ($ per

1,3$/Wp,

watt) for a suntracking system vs.

investment of 30 % more than a fixed

fixed?

system. In a location with high radiation you

this

means

approximately

an

can get increases of production by 33-40 %, but also you will have certain expenses for an extra maintenance. With high prices for panels, this equipment is very profitable.

2

With low prices for panels its employment is doubtful . Attention: the tracker use is complicated in case of zones with important wind

Where will sun tracking be useful in

Its usage is more profitable in locations with

diffuse or direct light? What is the largest large scale PV

a high direct radiation we recommend

installation in the world? Would it be possible to name some

http://www.pvresources.com/en/top50pv.php Our experience with PVSYST is very positive.

programs

to

make

browse

at:

shadowing

calculations? Does Leonardo Energy have a tool

Leonardo don´t have this tool, but we

for estimating or calculating the

recommend you to use the program PVSYST.

shadowing

You will need complementarily get certains

effect

for

dual

axis

tracking system?

data from sites as PVGIS or meteonorm, because this sites supplies radiation data

Do you have any experience or

wich you will need for PVSYST Except zones with important pollution, the

data relating to panel washing?

losses for dirt are not so high. If the zone is

What

module

rainy, our experience says to us that we

washing systems, as opposed to

must not clean panels. If there is very few

manual washing?

rain or the zone has a strong conditions of

about

automated

dirt, can clean them periodically. Please, analyze the production in a dirty string and in a cleaned one to verify the losses in bouth cases. With regard to the automatic option, please verify if 1. Your installation really needs cleanliness

2. The cost of doing it

manually 3. The cost of the investment of the

automatic

system and

its foreseen

amortization 4. Except very difficult cases, it is better not to get obsessed with the cleanliness

3

Can I clean the panels by myself or

You can clean them yourself. Important:

do I need an expert?

Please, pay attention to the used water because remains staying on the panels can be more harmful than the benefit obtained by the cleanliness. Preferably make a dry

How far can you place the inverter

cleaning with a soft brush Usually, if it will be better to put the inverter

from the modules (thinking about

near the panels, so we will minimize the

the losses)?

losses, because of we increase the voltage

What kind of output is the RS 485

It is a communication standard for multipoint

output?

systems, that allows the communication with a maximum of 32 devices and a maximum cable length of 1.200 meters. It is normally used with DB-9 connectors (the connectors

What means RZ-cable?

of a computer serial port) It is a cable 0.6 kV, free of halogens

Up to what extent the additional

With high prices for panels, this equipment is

costs for Sun Tracking systems

very profitable. With low prices for panels its

could be offset by the benefits

employment

gained in a given situation?

trackers with prices around 1,3$/Wp, this

is

doubtful

.You

can

find

means approximately an investment 30 % more than a fixed system. In a location with high radiation you can get increases of production by 33-40 %, but also you will have

certain

expenses

for

extra

Hello, Can we use AC Fus instead of

maintenance. It´s more correct to use DC fuse. Mind the

DC fuse?

voltage recommended by the manufacturer

Aren't concentrators useful only in

of AC fuses Concentrators only take advantage of the

areas with high direct and low

direct radiation, so you need locations with

diffuse irradiation?

good

meteorological

conditions

important part of the year

4

in

an

What is the best efficiency for

we

concentrating technology modules

http://www.isfoc.es/ and click the links that

that

you

you

can

buy

commercial

today? Who is the supplier? What is thermal coefficient?

recommend can

find

in

information Please,

browse this

site

at:

for

further

browse

at:

http://pvcdrom.pveducation.org/MODULE/He What is the degradation rate of thin

atLoss.htm to get more details about it The initial degradation of these modules in

film modules?

an initial stage is very high, therefore, the manufacturers

always

supply

an

initial

power in panel higher than the nominal one. Later

the

degradation

becomes

stable.

Though there is not an important experience in large facilities having been producing for many years, we can consider that the degradation during its lifetime will be similar to

the

crystalline

technology,

as

manufacturers offer the same production guarantee (90 % in 10 years, 80 % in 25 years) Definition:

What is PR?

Evaluation

criterion

for

solar

power plants, which is independent of the alignment of the solar power plant and the global solar radiation. The performance ratio is defined as the relationship between the actual returns and theoretically potential energy returns of a Photovoltaic system. The performance valuation

ratio

is

criterion

for

an

appropriate

determining

the

quality of the plant configuration, because all

components and

considered.

It

is

their interaction

independent

of

is the

orientation of Photovoltaic system and the global radiation

5

6