Solar panels for homes: cut your bill by producing your own energy

A standard single-family home usually needs between 8 and 12 panels of 450 W (3.6-5.4 kWp) to cover a typical consumption of 3,500-5,000 kWh per year. If you have an air-source heat pump, electric vehicle or swimming pool, the range increases to 14-22 panels.

At SolarTradex we size each installation based on your actual consumption and your future projection. We analyse your bill, roof orientation, shading, habits and medium-term plans to avoid unnecessary oversizing.

The standard contractual deadline for installing solar panels is up to 90 days from the signing of the contract to the completion of the installation on your roof. This margin covers all phases of the executive project, not just the visible on-site part.

Phases included in the 90 days:

• Technical study and project: visit, sizing and preparation of the engineering project.
• Administrative processing: request for municipal licence, ICIO, notice of works and other permits required by the town council.
• Purchase and logistics of materials: order of panels, inverter, structure and components according to the approved project.
• Installation execution: the visible part of the process. On site, the installation is completed in 1 to 3 working days for most residential projects.

The 90 days is the maximum contractual margin that allows us to absorb possible external delays (responses from the town council, material manufacturing timelines, etc.). In many cases the process is completed sooner.

Note: the subsequent legalisation (registration with the electricity distributor, RITSIC, RAC) is an additional phase that depends on external bodies and is not included in this contractual deadline.

In those self-consumption facilities with less than 100 kW of power and that are connected to the internal network of any of the consumers associated with the generation facility, the electricity company will value the surpluses (leftovers) that we send to the distribution network in accordance which is called simplified compensation mechanism.

Of the energy produced by the photovoltaic installation, the energy that cannot be self-consumed at the moment (solar surplus) will go to the electrical grid and the bidirectional meter of the marketing company will count hourly the total energy sent (exported) into the distribution grid.

Each electricity marketing company values the kWh sent to the network at a different price, adding their value during the month.

At the end of the month, when we receive the invoice, we will see a discount line with the total economic value of the kWh sent to the grid.

The electricity bill can never be negative, and therefore if the installation has many surpluses, a part of these may not be able to be valued and may be lost.

It is important to keep in mind that the value they give us for the surplus is always lower than the value we pay for the electricity consumed, and therefore we will always have maximum profitability and lower payback with installations with little surplus.

However, if we try to make an installation without surpluses, the resulting installation may be very small, and therefore the savings in absolute value will also be lower.

Therefore, the most appropriate thing is always to achieve an optimal balance between profitability (small installation with little surplus) and savings (larger installation with more surplus) that satisfies the client's needs, each client is different.

If we install a battery we reach the maximum value for each kWh generated, since we value all the kWh generated at the price we buy electricity at home. To achieve this maximum value, it is necessary to invest in the battery, which generally represents an extra cost of between 60% and 70% compared to the installation without a battery. This extra cost can be significantly reduced with the grants and subsidies currently available, which are especially focused on storage systems.

On the contrary, if we do not install the battery, the surpluses that would go to the battery will be sent to the electrical grid and will be compensated/valued at a lower price than if we had saved them. The advantage of not installing the battery is that you save that 60% - 70% extra cost.

If we think about buying a battery in economic terms, the amortization of the installation may be longer, but in any case the economic factor is not always decisive, since there are many people who buy batteries from us because they want to achieve maximum autonomy with respect to the electricity company.

Furthermore, we must not forget that as more solar systems are installed, the price of electricity during the day will fall and at night it will be more expensive, and therefore it will be more profitable to install batteries.

Standard self-consumption installations automatically disconnect during a power outage for safety reasons. Regulations require solar installations to stop working when they no longer detect voltage from the grid, in order to protect operators who may be working on the distribution lines.

If you need coverage during power cuts, the solution is to include a battery with backup function. This combination allows your installation to keep powering essential circuits of the home (fridge, lighting, router, alarm) even during a supply outage.

Backup batteries are sized based on real energy needs and provide greater energy independence and security against unexpected events.

To learn more, on our blog we explain how solar panels and batteries improve energy resilience against power outages.

Yes, it is part of our turnkey service. We take care of all the technical and administrative paperwork so you only have to decide when we start.

Installation legalisation:

• Electrical certificate and installation report
• RITSIC registration
• Self-consumption registration with the regional authority
• Activation of the surplus energy compensation with your electricity retailer
• Paperwork with the distribution company

Study and management of applicable grants:

• Personal Income Tax deduction (up to 60% with double Energy Efficiency Certificate)
• IBI (property tax) reduction (up to 50% for 3-5 years depending on the municipal ordinance)
• ICIO (construction tax) reduction (up to 95%)
• Regional and municipal grant programmes when available

We analyse the grants available in your specific case and let you know what requirements and documentation you need to apply for them.