How I powered-up my home with ONE solar panel

The wonderful sunlight of the Lebanese mountains

I've recently completed the construction of my vacation home in the middle of one of the numerous picturesque villages of the Lebanese mountains, at some 1200m of altitude, and at the bottom of a mountain cliff populated with a wide variety of pine and oak trees.
The surrounding forest is home to several species of birds and wild animals: crows, falcons, eagles, partridges, jackals, foxes, weasels, voles, and many more...

In such a context, one can hardly imagine turning on a diesel genertor to power-up his/her home, or worse (?), fitting 6 to 8 solar panels on the roof, which destroys the beauty of the roof tiles and produces a harmful mirroring effect pointing towards the piercing gaze of the flying raptors.

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How solar power can be made sustainable

The decision was taken and sustainability was considered in all its aspects:

• Minimum investment and no excess money spending
• Aesthetics of the roof not to be disturbed by PVs
• Combination of two renewable sources of energy: wind and sun
• Battery storage kept to the strict minimum
• Daily life habits while on holidays, adapted to the sun availability
• A complete off-grid setup for an absolute peace of mind
• Voltage not exceeding 24VDC on the DC side, to maintain the electrical safety of the installation and protect people all along the 25 years of lifetime of the solar system.

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How to power-up a home with a single PV!

The single 545W solar panel was installed directly on the roof tiles while an 800W wind turbine provides some additional energy during winter and storms. 

The details of the renewable energy off-grid and autonomous system are as follows:

• One 545Wp solar panel providing 31.4V (Vmp) and 17.37A (Imp)
• One wind turbine of 800W, starting at a minimum air speed of 1.3m/s
• Two flooded lead-acid batteries of the automotive type,100Ah each, connected in series.
• One Hybrid wind-solar controller and battery charger
• One 24VDC battery inverter, true sinewave, 4000W max, 2000W continuous.
• One 12VDC sub-system charged from the 230V output of the inverter and consisting of a 60Ah battery (lead-acid, automotive) linked to a 12VDC 1000W battery inverter. This feeds the TV on one hand, provides a spare capacity, and also a backup in case of failure of the main 24VDC system.
• Necessary breakers, surge arresters, etc. for the safety of the installation

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The total cost of the above solar - wind system is around 1500USD not including installation, the latter having been carried by me; this results in a payback period of approximately one year and up to a maximum of 14 months, compared to equivalent utility energy bills.

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Here's why one solar panel is enough...

1- Location where the PV is used

This solar panel is installed at 1200m altitude facing the Eastern Mediterranean see. The climatic conditions are much favorable since:

• The PV is away from city pollution
• Humidity is very low, which results in less diffracted sun rays
• Summer fogs and clouds "hang" lower than the location of the house, except by late afternoon, if and when fog advances into the mountain.
• The solar panel orientation is South.

The sunset as seen from my terrace on a day of November

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2- Simple automation and life habits associated with the solar panel installation

To make it work with one and only solar panel, I have fitted very simple automation devices to the system in order to:

1. Forbid the booster water pumps from running at night, i.e. I linked them to the photocell that turns on and off the garden lights, and set the photocell to the maximum lux position. One can also use the output of the solar controller for this purpose.
2. Turn off the fridge between 1AM and 7AM, except during summer.​
3. The water heater is being dealt with in a separate system which I will detail in another blog post.
   

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Other daily life habits are observed by my family in order to adopt a "solar lifestyle":

1. Coffee machine, small kitchen cooking appliances and washing machine are used only between 9 AM and 3 PM.
2. The washing machine is set to cycles with no heat.
3. No dishwasher
4. No A/Cs or fans, the house is also designed in a manner to oppose its insulated roof to the midday and afternoon sun, while openings do allow the main wind to cross the house and cool it down. All walls are double masonry walls with 20mm thick insulation in between. Windows are made of wood and double glazing.
5. When reaching the holiday home on Friday evening, the fridge is only loaded with frozen food, while other grocery items and drinks do wait for Saturday morning before being moved into it.
6. No excess light, all lamps are 3 to 9W LED and walls are painted in white.

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That's it! An entire home is powered-up by the Sun, using a single PV!
The electricity occasionally generated by the wind turbine, is a bonus.
I do have indeed a 5KVA diesel generator installed as a backup for weekends with no Sun or Wind, also during storms with low and frequent lightning strikes.