The system is designed to run conventional load with 12VDC. It has a 1500W power inverter. This system will run AC loads such as a laptop, radio, CFL lights, and sleep apnea machines. The 12VDC outlet can be used to power cell phones and small appliances which plug into the standard car cigarette adapter. We would install a 12VDC fan in the near future to improve airflow from the loft room and circulate the heat.
The solar module system was designed for summer weekend usage where the battery is charged to about 50% and then the modules are used to recharge the batteries. We have a backup generator that will power the cabin if the batteries run out during our trip. The solar panels can then charge them back up.
We plan to install a 55A external battery charge (1500W load), which will be powered by the generator (2000W capacity), to recharge the batteries. It has a built-in 8A battery charger but it is not enough to charge our bank of batteries. The battery charger is intended for car battery trickle charging. Battery chargers should be at least 10% (44A) of the battery bank’s capacity and can go up to twice that amount.
The batteries in our system are sealed inside a battery enclosure to keep the hydrogen gas from entering the house. This box has a vent to let the gas escape. It is a safety measure that should be included in any system that uses flooded lead acid batteries.
Our power system requires minimal maintenance.
Solar modules should be free of any debris, and they will be cleaned with water if necessary. We can also use dish soap to get rid of more stubborn obstructions. Solar modules should not be cleaned with harsh chemicals. Solar modules must be free from shading and clear. Each module contains two solar cell strings. We lose nearly 50% of our module’s charging power if one cell gets covered. Even if only a portion of the solar module is shaded, a shadow cast by a tree branch can cause the module to be destroyed. We have our solar panels mounted in an area that is shade-free, so we will not experience any problems. If you cannot avoid shading (like on a boat), then Amorphous modules are better than Crystalline ones. The Amorphous type modules cost more and are bigger per watt than the crystalline ones, but can handle shadows better. If 5% or more of an amorphous panel is shaded, you lose about 5% in charging power. This is much less than the 50-100% loss of charging capacity with a crystal module.
Periodically, the batteries’ electrolyte/water levels will have to be checked. If you use the cabin continuously, then check the electrolyte/water level at least once a month. For occasional weekend usage, it should be checked twice per season. Record the readings of each cell’s specific gravity using a Hydrometer. The readings of all the batteries should be very close. Batteries will only need to be filled with de-mineralized or distilled water. Never use tap, spring or well water as the minerals will cause the electrolyte to be contaminated and shorten the life of the batteries. We will then use the generator and bring them up to full power. The batteries will all be at 1.265 SG when fully charged. Batteries that have not been fully charged or batteries that age will show a lower reading. This is the only maintenance that we can perform on batteries using our system.
We can do an equalization charging to raise the specific gravity if we have a charger that has an Equalization cycle. (Ours doesn’t). A battery equalization charge involves an intentionally overcharge to boil acid and remove sulfate from the plates. It can increase the life of your batteries. With proper maintenance, the 6V batteries will last 5-6 years if used continuously. We could use these batteries for 8-10 years since we only use them at weekends during the summer.
Equipment list:
- Sharp 80W Polycrystalline Solar Modules (up to 800-Wh/day).
Roof mount aluminum solar rack with adjustable height - Specialty Concepts Mark series 22A PWM Solar Charge Controller with
Battery voltmeter with solar charging ammeter and integrated fusing - Midnight Solar Mini DC disconnect box
Two 10A-12VDC load breaker and 250A inverter breakers.
DC Lightning arrestor;
The batteries are connected via two 4/0 cable lengths of approximately 5ft. - Golf-cart battery – 4 x GC220 (440Ah at 20hr discharge rate).
Total capacity: 5.5kWh; usable capacity 2.75kWh (maximum drain of 50%). - Samlex S-Series 1500W (heavy duty commercial) true-sine wave inverter
Remote on/off Switch
Load centre for AC 100A with 8 positions and 4 AC 15A breakers - Custom DC wall outlets (car lighter style) 12VDC.
- Honda EU2000 Generator 2kW for Backup
- All of our equipment has CSA approval