ABOUT WHY GRAPE PEOPLE CAREERS COMMON QUESTIONS
Q: Will I get more power by using higher wattage panels on my roof?
A: All crystalline solar panels have similar power production per square foot. In most cases a higher wattage panel will take up more roof space. By using a smaller panel, the increased number of panels that will fit on the confined space of a rooftop will offset the gains of having more watts per panel.
The diagram below shows an actual rooftop with two panel options. The green rectangles represent our large 400W panels and the red represent our 190W panels. Only 17 of the large panels fit on the roof, creating a 6.80kW system. On the other hand, 46 of our 190W panels fit on the same space creating an 8.74kW system. More power can be generated by a system using smaller panels.
Q: Do you offer logistical support to solar system installers and design teams?
A: Absolutely. Grape Solar offers on-demand delivery, design services, and around-the-clock access to customer service representatives. If you have a large project, we can establish a local hub (distribution warehouse) for modules and have them delivered to your jobsite on a weekly schedule. To talk about your unique needs, please contact us
Q: Do you also sell inverters? Racks, pole mounts, ground mounts, trackers?
A: Yes. Upon request, Grape Solar can source all installation components at the most competitive prices. Grape Solar is becoming the installers' choice for one-stop-shopping.
Q) Why do I need an MPPT charge controller? Can’t I just connect my panels directly to the battery?
A) A charge controller specially designed for use with solar is called an MPPT Charge Controller. An MPPT charge controller regulates current to prevent overcharging and backflow from the battery to the solar panels. Without a charge controller, a battery will overcharge, which could lead to explosions, fires, etc.
Q) What voltage should I make my battery bank?
A) The voltage of a battery bank can be manipulated by changing the number of batteries or modifying the battery series/parallel connections. Two 12V batteries in parallel will result in a battery bank voltage of 12V, while two batteries in series will result in 24V. In order to reduce equipment costs, decrease the operating current and minimize power losses, battery banks should be designed to achieve the highest possible voltage. The battery bank voltage should always be lower than the voltage on the panel side of the charge controller and under 60V for safety.
Q) How do I select the right MPPT charge controller?
A) Charge controllers are rated by current and voltage. Typically current is the most restrictive property. To determine the current take the DC system size in watts divided by the battery bank voltage.
For example:
If someone has two 220W panels their DC system size is 2 x 220 = 440W.
If they want to charge a single battery the voltage is 12V.
The current passing through the charge controller is 440W / 12V = 36.6A
In the real world, the panels only produce about 90% of the rated power and batteries charge at slightly higher than their 12V rating. 90% x 440W = 396W, 396W / 14V = 28.3A 28.3A
The breakdown for charge controllers is typically 10A, 15A, 30A, 60A, etc. In this situation, fortunately a 30A charge controller is adequate. Doubling the current limit from 30A to 60A triples the price. The 10A charge controllers are perfect for 12V systems using a single 100W panel.
If someone has two batteries, they may be able to connect the batteries in series, thus doubling the voltage and cutting the current in half. 396W / 28V = 14.1A
See the diagram below for wiring instructions.
