Home Renewable Systems: Solar PV and the Tesla Powerwall, Heat Pumps, and More

Renewable energy has been a main focus of the energy sector for many years now. Harnessing, wind, wave, and solar power would mean essentially free, clean energy. No more burning of hydrocarbons, meaning less pollution into the atmosphere and more oil and gas available for the production of other goods; oil derivatives are used heavily in pharmaceuticals, clothing, packing, and many other areas.

The advancement of technology in the industry does not only benefit companies and governments. Homeowners are now able to access small-scale renewable and sustainable solutions, such as heat pumps, biomass generators, and solar panels. Combine these with a home battery system – such as a Tesla Powerwall – and you have a system that allows homeowners to be at least semi-independent from the energy providers.


Biomass Boilers

An alternative solution to a traditional gas or oil boiler, biomass boilers are carbon neutral, sustainable, and safe. They work by burning wood pellets, chips, or logs to provide warmth in a single room or to power home central heating systems. Most biomass companies ensure carbon neutrality by planting trees. Every carbon molecule released into the atmosphere through biomass burning, another is absorbed through the replanting of trees.

Solar PV and the Tesla Powerwall

Solar PV stands for Solar Photovoltaic. This describes the process of power generation; the element silicon creates an electrical charge when exposed to sunlight. The technology for solar panels has been around since 1954 when this phenomenon was first observed, and soon it was in use in space tech and powering smaller items such as watches.

Solar PV in the home is usually found in the form of solar panels on roofs or in gardens, depending on which location gets the most direct daylight hours. They are attached either directly to the home circuit or to a home battery system such as the Tesla Powerwall. If attached directly to the circuit, a solar PV supply may provide some or all of the homes requirements for energy. If there is a shortfall from the solar, it will be covered by electricity drawn from the grid. If the solar supply is larger than the power demand, the excess is sold back to the grid.

If a homeowner has a home battery system, the solar supply will feed into the home battery. The home circuit will draw energy from the battery while there is electricity available. If the battery charges to capacity, excess energy is once again sold back to the grid. Batteries such as the Tesla Powerwall can also load shift, allowing a home to be as cost-effective as possible. Load shifting is where the battery system charges from the grid at low rate times, before covering the energy demand during the high rate periods. This allows a homeowner to pay the lowest rate for the largest amount of time possible.

Solar Thermal

Solar water heating (known as solar thermal) systems capture the heat of the sun and use it to heat up a home’s water supply. The process is simple:

  • Panels on the roof absorb heat from the sun – these are known as the collectors.
  • The water in the panels heats up.
  • This hot water is pumped through a coil in your cylinder.
  • Heat is transferred from the hot collector water to the water in the cylinder.

Solar thermal is ideal for south facing homes, although it is suitable for anything facing between south east to south west. How much hot water they provide is down to the amount of collectors installed; in general, a house requires between 1-2m2 of collectors per person. They are most effective in the UK between April and September, so should be used as a supplementary cost-reduction technique rather than a main supply.

Air Source Heat Pumps

Heat pumps are based of clever use of physical sciences to move thermal energy from a cooler environment to a warmer one, with the warmer being known as the “heat sink”. Air source heat pumps tend to be vapour-compression cycles. They are based around a fairly simple physical principle:  heat will move from areas of higher temperatures to those of lower temperatures.

By manipulating certain aspects of the physical situation, heat pumps can draw heat from the surrounding air which is then used to vapourise water or another similar heat transfer liquid. The resulting vapour is compressed, increasing its temperature, and sent to a condenser in the appropriate area. The heat is then extracted from the compressed vapour, causing the fluid to revert to its liquid form. It is then passed back to the evaporator to complete the cycle.

Heat pumps require a minimal amount of energy to run but are far cheaper in cost in comparison to traditional home heating systems. They are also simple systems that can be easily fixed and/or replaced, making life easier for homeowners.

Ground Source Heat Pumps

Ground Source Heat Pumps, or GSHPS, use pipes buried in the garden to extract heat from the ground. This heat is then transferred to the home heating system to heat radiators, underfloor or warm air heating systems, and the hot water in your home.

A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe, called a ground loop, which is buried in your garden. Heat from the ground is absorbed into the fluid and then passes through a heat exchanger into the heat pump. The ground stays at a fairly constant temperature under the surface, so the heat pump can be used throughout the year.

The length of the ground loop depends on the size of your home and the amount of heat you need. Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, a vertical borehole can be drilled instead.