How to Build a Low Cost DIY Solar Panel System For Your Home

Installing solar panels on your home can reduce or even eliminate your electricity bills. With the cost of retail solar panel systems still high, building your own DIY solar panel system is an affordable alternative for environmentally conscious homeowners. In this guide, I will walk you through the entire process of constructing a low cost solar panel system with affordable components from local hardware stores.

Determining Your Energy Needs

The first step is calculating how much energy you need your DIY solar panel system to produce. The key factors are:

• Your average monthly electricity usage - Check your past electricity bills to determine how many kilowatt-hours (kWh) you consume each month. This will establish the minimum size solar system you require.

• Future energy needs - Consider any upcoming electric vehicle purchases or home additions that may increase your energy usage. Adding 20-30% more solar capacity than your current usage will help future proof your system.

• Sunlight availability - Use a solar resource map tool to estimate how many peak sun hours your location receives per day. More sun = smaller solar system required.

Take these variables into account when designing your system's production capacity. Overestimating is better than underestimating your energy needs.

Choosing Solar Panels

Monocrystalline and polycrystalline solar panels are the most efficient and affordable options for home DIY projects. Here's how they compare:

• Monocrystalline - More expensive but slightly more efficient (15-22%). Made from a single crystal silicon wafer.

• Polycrystalline - Slightly lower efficiency (15-18%) but cheaper per watt. Made from multiple silicon crystal fragments.

For a DIY solar newbie, I recommend polycrystalline panels as they provide a good balance of cost and efficiency. Shop for panels in popular wattages like 250W, 300W or 330W. Buy from reputable brands like Renogy, Rich Solar or WindyNation.

Calculating Number of Solar Panels

To calculate the number of panels needed:

Total watts required = Average daily usage (kWh) x Days of autonomy

Number of panels = Total watts required / Watts per panel

For example, if your average daily use is 30kWh and you want 3 days of backup, you need 30kWh x 3 = 90,000W. With 300W panels, you will need 90,000/300 = 300 panels.

Sourcing Components

Here are the key components to source for your DIY solar system:

• Solar panel mounting racks - Sturdy aluminum racks to mount panels on your roof.

• Charge controller - Regulates power from panels to batteries. Size for 1.25-1.3 times total solar wattage.

• Batteries - Deep cycle lead-acid batteries to store power. Calculate total storage capacity required.

• Inverter - Converts DC from batteries to standard AC power. Size for 30% over typical use.

• Wiring and connectors - Copper wiring, MC4 connectors to link components.

• Circuit breakers - Overcurrent protection between each system component.

Online solar retailers like Renogy, WindyNation and Wholesale Solar are great places to source these items. Brick and mortar stores like Home Depot also carry limited solar equipment.

Structural Considerations

Your roof structure needs to be assessed to see if it can support the additional weight of the solar panel system:

• Panels will add 3-6 lbs per square foot across your roof.

• Consider hiring a structural engineer to evaluate your roof's load capacity if unsure.

• Reinforce roof members or trusses if required to handle the panel weight load.

Also check with your local permitting office to see if any approvals or permits are required to install a DIY solar system where you live. Better to verify this ahead of time.

Mounting Solar Panels on Roof

Once you have all the components, it's time for installation:

• Mark out each panel location on the roof using measurements and chalk lines.

• Bolt the aluminum mounting racks onto roof rafters based on the manufacturer's specs.

• Secure each solar panel frame to the racks using the supplied hardware.

• Ensure panels are oriented towards true south if in the northern hemisphere.

Take precautions when working on a roof including safety harnesses, erecting barriers and having someone there to assist you.

Connecting Components

Follow these steps to wire up the full DIY solar system:

• Use copper wires to connect the solar panel frames together in series (negative to positive).

• Run conduit from the panel array to your indoor equipment location if required.

• Attach the wires from the panels to the solar charge controller input.

• Connect deep cycle batteries together in series and then to the charge controller output.

• Link the inverter output wires to your existing electrical panel.

• Connect all system grounds together to earth ground.

• Install appropriately sized circuit breakers between each system component connection.

Consult a qualified electrician if unsure of how to make wire connections. Use cable strain reliefs and waterproof all outdoor connections.

Configuring and Testing System

Before turning on the system:

• Program the charge controller and inverter as per manufacturer's instructions.

• Check all wiring connections and torque to specified levels.

• Verify the DC and AC voltages at each connection point.

When ready for testing:

• Switch on the charge controller and slowly charge the batteries over 3 hours.

• Power up the inverter and connected appliances/lights to verify proper operation.

• Check the charge controller displays to see panels charging batteries as expected.

Take time to monitor voltages and currents during initial operation. Your DIY solar system should now be up and running!

Maintaining the System

Like any power system, some periodic maintenance is required:

• Inspect all wiring connections, mounting racks and panels for damage or corrosion.

• Check that vegetation is not shading any part of the solar array.

• Use battery equalization mode on the charge controller every 3 months.

• Clean dirt and debris off solar panels with water and a soft brush.

• Replace batteries every 5-7 years depending on use.

Performing regular maintenance will maximize system performance and lifetime.

Building your own solar panel system takes research, careful planning and installation. But with smart component selection and safe wiring practices, you can harvest free energy from the sun for decades to come. The solar energy you produce will mitigate your home's carbon footprint and protect the planet for future generations.