Solar panels for home

Whether you are interested in installing solar panels for your home or looking into a commercial solar photovoltaic power plant, before commencing on such an investment you need to identify what your project entails and assess its financial viability. Herein we provide some essential advice on making such an assessment of solar panels for your home.

Before installing your residential or commercial solar panels you need to gather the relevant information, consider it in a structured form and answer some simple questions – this post is a guide to assist you in your decision for your home solar panels:

What type of solar panels installation?

The first thing to decide is the type of solar PV panels – whether interested in Residential Solar panels or a commercial solar PV power plant. Solar panels for your home can be roof mounted solar panels or land mounted solar panels depending on what suits your case best. What is important to note is that solar panels should be faced South at an inclination of approximately 29-35 Degrees (subject to location’s latitude and season of the year). The decision on the type of solar panels installation mainly depends on your orientation (allowing unobstructed face to the South) and limitation of space.  A commercial solar power plant comes in land-mounted solar panels with different supporting structures, panel sizes and overall size scale.

What size of the solar panels installation ?

The size of your solar panel installation will be influenced by the type (residential or commercial) and by other factors custom to your circumstances. Usually, for residential solar panels,  roof-mounted solar panels come to a size of 4- 10 kw of installed capacity (depending on the available effective area of your roof) whereas land-mounted can be larger (usually up to 20kw), subject to your specific circumstances.

Relatively small commercial solar power plants usually come at sizes between 20 kw – 150 kw of installed capacity subject to the relevant parameters such as climatic conditions, terrestrial circumstances, solar power plant subsidy schemes, technical and economic criteria of financial incentives – such as maximum sizes allowed, Feed in Tariffs (FITS), technical criteria for connection to the power grid etc.  Effectively the size of your home solar panels may also be a function of your annual avarage power consumption.

What is the cost of solar panels?  – Home solar panels cost per kw

Before assessing solar panels cost, you should try gathering comparable solar panel prices from potential solar panel installers. Quoted prices should be in a comparable form such as cost per kw of installed capacity (e.g. $/kwp) and solar panel prices should state clearly what they include (e.g. if they include the complete solar panel installation kit with inverters and other equipment, if solar panel installation costs are included, etc). Effectively, the overall solar panels cost will be comprised of the sum of the following cost drivers:

• Purchasing Solar panels cost (cost of purchasing the solar panels as $/kw installed)
• Purchasing cost of additional equipment such as inverters, supporting structures, cabling, electrical meters etc.
• Solar Panels installation cost ( the cost to install and connect your system)
• Associated costs for connecting your solar panels to the power grid

You may get an insight into these cost drivers by doing some simple research from solar panel installers and solar panel companies who should be able to issue you with a detailed price quotation (fyi – latest solar panels cost). In case of a small commercial power plant (or residential land-mounted solar panels) some additional costs may include special fencing and installation of a small power station before connecting to the power grid.

The column on the right shows corresponding values of a case-specific example: Case-study example (values are included as an example of a specific case of a residential solar panel installation) – values used may not be applicable to every case.

Guidelines on solar panels for your home

This section is a guide for your home solar panels – figures in ‘[ ]’  are the actual values from a specific case of a residential solar panel installation – included for  illustration – these values are not be applicable to every specific case.

Home Solar Panels Technical specs             

• What is the Total Installed Power capacity of your home Solar Panels (wp) ? – [7(kwp)]

• What is the Power per solar panel (Wp) ? - [250 (w)]
• How many Solar Panels are used? – [28 panels]
• What type of Photovoltaic Solar Panels (Monocrystallic, polyCrystallic, or other)? – [monocrystallic]
• Note the Solar Panel Model /code – [model – brand (n/a)]
• Note the Solar Panel Manufacturer – [manufacturer (n/a)]
• Note the Solar Panel Installer

What are the site and installation specifications of your Home Solar Panels?   

• Are you using Stationary or Tracking solar panels – [stationary structure]

• What is your Solar Panels orientation to the South: Inclination (5-45 deg)/diversion (-35, +35deg) from South- [27deg.South- 0 deg.]

• Is there anything obstructing direct sunlight to your home solar panels? (eg. chimney or vertical protruding pipes on the roof or nearby trees or buildings?) – [No obstructions]

If you are using roof-mounted solar panels for home you must note:

• What type of roof for your solar panels? Flat or inclined roof? [Flat roof]

• What is your roof surface area? [210 sq.meters]

• What is your roof inclination to South?   [N/A]

If you are using Land-mounted home solar panels:[NO]

• What is the land area for your home solar panels? [NO]

• What is the Total surface area (inclined or flat) used for the installation of your home solar panels (sq. Meters)?

• The overall area should include the empty gaps / pass-ways between your solar panels. [122 sq.meters]

Solar panels performance warranty

• What is the solar panel manufacturer’s given performance warranty? – This is the warranted solar panels output performance for a period of years (e.g. for the first 10 years of operation) and is expressed as a percentage (%) to the nominal output power of the solar panel.

• What is the solar panel warranted power output for the first period of power-output-warranty?  [at least 98% in first 10 years]

• What is the solar panels warranted power output for the second period of power-output-warranty?    [at least 92% between 10-20 years]

What is the Output of your Home solar panels installation?

Considering the specifications of your home solar panels installation (location’s solar radiation data, your home site circumstances, solar panels technical specifications, solar panels inclination, effective radiation data and other related details) you should be able to have an estimation of the annual energy generation of your home solar panels. When you discuss with potential solar panel installers and solar panel companies for your home solar panels it is advisable to ask for the estimated annual energy output per installed kwp. i.e. this is the annual energy (kwh) produced by a 1 kw solar panel and depends upon all above mentioned specifications; however, the two most important of all are:

• the Power output of your solar panels (kw) and
• the Solar Irradiance levels in your location (kWh /m2 /day) – (available at National meteorological orgs or Publicized Irradiation Data Charts – per country,  location etc.) – [solar irradiance data of the location and solar panel specifications suggest annual energy production per kw of: 1708 kwh/kw]

What are the costs for a Home solar panels installation?  –  Costs-benefits analysis of home solar panels.

If you are thinking of the investment cost versus the benefits incurred then you should consider your residential solar panels project as an investment project. Consider your Net one-off initial costs as the actual one-off investment for your home solar panels installation. Once your home solar panels are operational they will require minimum maintenance expenses (running operation expenses – recoded monthly or annually) and they will start yielding income or savings from solar electricity. Your solar panels income or savings will be subject to the type of financial incentive applicable to your project.

To sum up, the financial viability to your residential solar panels can be evaluated with a cost-benefits analysis of your home solar panels as follows:

• (-) Total net solar panels cost (overall one-off initial investment net of any initial subsidy or grant from incentives)

• (+/-) Running performance

• (+) Running income or savings from home solar panels operation

• (-) Running solar panel expenses (e.g. maintenance, insuring income, etc.)

• (-) Running financial expenses (cost of financing your investment if through a loan).

Thus through a net cash flow analysis recording your net monthly or annual cash inflows and outflows you will be able to determine if your project is viable and to what extent. Below there is a break down of the main solar panels costs:

Purchasing costs of residential solar panels kit.

Solar panels Cost (purchasing of the solar panels), Cost of inverter / transformer, Cost of cabling and solar panels monitoring equipment ( DC/AC switches, electrical circuit protection etc) and Cost of supporting structure of the Solar panels

Installation Costs

Installation costs of PV panels, supports, inverters, wires and switches

Connection Costs

Connection cost of your home solar panels to the electrical power grid

Other Site costs

In cases of small commercial solar plants or residential land-mounted solar panels additional costs may be required such as installing a proper fencing or installing a small power station.

Overall solar panels cost – quoted solar panel prices for small scales of residential solar panels – latest solar panels cost for installations of up to 10-15 kwp in size, quoted prices range between €2000-$3000 per Kwp. Larger installations of up to 100 kpw have a considerable lower solar panel cost ($/kwp – around $1600/kwp) –  [$2000/kwp]

Financial Incentives for your Home Solar Panels             

Financial incentives are provided by federal, state and municipal governments and authorities to encourage the application of renewable energy technologies and green practices. Green technologies without the help of financial incentives are still financially non-viable. In order to promote their use, authorities, globally, are providing financial incentives to compensate for the extra cost incurred to go green or the high investment costs. Solar Panels for your home can be incorporated within financial incentives for the use of renewable energy sources and depending on the energy policy schemes enforced in your country, state, municipality, differently attributes may apply. It is advisable to consult with local authorities and understand what type of financial incentives apply in your case for home solar panels. The list of financial incentives for solar panels below is by no means exhaustive but only for your own quick reference. Incentives may include Tax credits, rebates, property tax incentives, or cash any form of discount or subsidy. some useful links for US solar panels incentives are listed below:Some useful links on the Financial Incentives available in the US.

Residential Solar Panels FITs scheme example 

FITs per kwh produced – In case of government financial incentives through FITs (Feed In Taiffs) you will receive a fixed subsidy rate per kwh of electrical energy produced from your home solar panels. So for example, if you have a 10 kw solar panel installation and a FIT’s of say 0.35 $/kwh then your annual solar panels income will be as follows:

• Annual energy production is (10 kw x 1708 kwh/kw) = 17,080 kwh
• Annual FITs income is 0.35 $/kwh x 17,080 kwh = $5,978

Note: these figures are not representative of every case and should only be used for illustration. You should also note that solar panel output figures are not static and change throughout the months, seasons and over the year, and diminish over the passing years. – [0,35 $/kwh]

The above information can be used as a guiding checklist for solar panels for home. The values shown in “[ ]” are neither universal nor generic and do not apply to all cases, but correspond to the specific circumstances of the solar panel installation.