Frequently Asked Questions
Click Questions to expand Answers
- Q: What voltage are your panels? Will they work with my 12V, 24V or 48V system?
In short, Yes, but it must be done correctly. Like all crystalline PV modules, the voltage at which the panel produces optimum power varies widely depending on the temperature and brightness. Connecting the panel directly to a load forces the voltage to remain fixed resulting in drastic losses. The Solar IV Curves (shown below) demonstrate how current and voltage are related to each other in the output of a solar panel. The graph shows how making the voltage too high reduces the current and making the current too high reduces the voltage. When the brightness of the sun decreases, the curve moves down and the current drops. When the temperature increases the curve moves to the left and the voltage decreases. For example, Florida and Oregon get similar solar output because Florida gets more sunlight but has higher temperatures than Oregon.
The MPP (Maximum Power Point) is the position along the IV Curve where the most power is produced, in other words, the point where Voltage X Current = the largest number. Power is represented by the size of the shaded box. Since minor changes in the brightness of the sunlight and the temperature cause this point to move, the panels need to be operated through an inverter or charge controller with MPPT device (Maximum Power Point Tracking.) The MPPT device finds the voltage point where the panel produces the most power and continuously adjusts that point as the temperature and brightness change. A Grape Solar engineer will be able to help you select the charge controller that works best with your 12V, 24V or 48V system.
- Q: How much power will the panel produce?
- A: Panel output is measured in watts and labeled by its performance under standard test conditions. For example, a 220W panel will produce 220 watts (0 to +3%) when the temperature is 25°C and it is exposed to 1000W/m2 irradiance. If a panel is operated under these conditions for 5 hours it will produce 1.10kWh of electrical power (5h x 220W = 1100Wh.) If the temperature or brightness change, the output of the panel will also change. Panels produce the most power when the temperature is low and the sun is shining brightly.
- Q: How many panels will I need for my house?
A: This depends on what percentage of your electrical consumption you will want to cover. Because of roof size limitations and budgetary constraints, a typical solar enthusiast will cover one-third to one-half of their electrical consumption with solar energy. A Grape Solar engineer or local installer will be able to run an analysis based on your total annual consumption, factoring in variables such as climate and latitude, to determine the system size that works best for you. For example, a small home in Eugene Oregon with an average consumption of 700kWh per month will require 36 of our 220W solar panels to cover 100% of their electrical bill.
- Q: How should my solar panels be positioned in order to produce the most power?
- A: To get the most out of your solar panels you need to maximize the surface area exposed to the sun. For installations in the Northern hemisphere it is recommended that your panels be installed pointed in a Southern direction at an angle slightly less than your latitude. A qualified installer will help you determine the best mounting configuration.
- Q: How will your panels hold up during strong hail storms?
- A: Grape Solar panels can withstand 7.53g hail (about 1 inch diameter) travelling at terminal velocity, repeatedly hit from different directions. Our panels can tolerate 5400Pa of snow load, 0.6 meters of ice and an impact from a 51mm steel ball weighing 535g dropped from a height of 1.292 meters.
- Q: What are some of the incentives for installing solar energy and how can I take advantage of them?
- A: Because Grape Solar customers are located all over North America it would be impossible for us to be able to provide current and reliable information on the rapidly changing incentives which vary by state and even by utility company. By contacting Grape Solar we will be able to connect you with a qualified installer in your area who will be able to clearly explain the various incentive programs and provide a financial analysis on your project. In the mean time, you can visit: http://www.dsireusa.org
- Q: What are the differences between grid-tied and off-grid systems?
A: A grid tied PV system uses an inverter to convert the DC current from the panels into AC current which is fed onto the electrical grid. The local utility company bills you for the difference of what was used and what was produced. An off-grid system uses a charge controller to regulate the current from the panels to charge a bank of batteries and an inverter converters the DC current from the panels and batteries into AC for use with electrical devices.
- Q: Will I need batteries to power my home after the sun goes down at night?
A: Grid tied PV systems are designed to feed the grid when power production is higher than usage and draw from the grid when usage is higher than production. At night, power will be drawn from the grid and no batteries are needed. A well designed PV system that covers 100% of the home owner’s electrical consumption feeds the grid and draws from the grid in equal amounts. Disconnecting this system from the grid and adding a battery backup won’t affect the electric bill but it will roughly double the cost of the system.
- Q: Will the Grape Solar kits power my home during a utility outage?
A: The standard Grape Solar kits are grid tied and do not have battery backup systems. These kits will only reduce the amount of power you have to purchase from the grid, not protect you during an outage. If you require a system that does protect your during an outage we can design a custom kit with a battery backup.
- Q: How do Grape Solar PV modules compare in price to those of other suppliers?
A: Grape Solar is the low cost leader in the solar panel manufacturing industry, due to our scale of production and technological leadership, our per watt cost is ALWAYS lower than our competitors when comparing apples to apples on: product specifications, delivery time and volume of purchase, Grape Solar guarantees the lower prices, always.
- Q: Where are the PV solar modules manufactured?
A: Grape Solar utilizes contract manufacturing which means we design the specifications and set the quality standards for our panels which are made in over 30 different factories throughout the world. These factories are located in Japan, Korea, China, Canada and the United States. If a customer requires Made in America panels, we can deliver.
- Q: What are the differences between mono-crystalline and poly-crystalline Si solar panels?
A: Essentially they are the same product because of identical behaviors under sunshine, similar electrical output performance, and similar temperature characters. But, polycrystalline wafers are cut from a block of silicon that was created by molten silicon being poured into a mold. As the silicon cools many irregular crystalline structures form within the block, hence the name “poly.” Monocrystalline wafers on the other hand, are cut from an ingot of silicon that is composed of a single crystal with uniform structure throughout. The manufacturing process for monocrystalline wafers is much more complex and involves a seed crystal being dipped into the molten silicon and carefully pulled out as the atoms arrange themselves uniformly into the structure of a single crystal. The boundaries between separate crystals in polycrystalline wafers inhibit the passage of electrons thus making polycrystalline cells less efficient than monocrystalline cells. In summary, assuming equal power output, a monocrystalline solar panel will be slightly smaller than a polycrystalline panel.
- Q: Who are your customers?
A: Grape Solar has four main target markets which include End Users, Installers, Developers and Custom Requests. Grape Solar will gladly talk to anyone no matter how small their project.
- Q: What kind of warranties cover your solar products?
A: In most cases, and unless otherwise noted, our product warranty is:
10 years product materials and workmanship
10 years output power assurance: no less than 90%
25 years output power assurance: no less than 80%
Our warranties are insured and backed by our contract manufacturers.
To learn more, see Warranty
- Q: How can I trust Grape Solar to be around long enough to honor their warranty?
- A: A common misconception about Grape Solar is that we are a young company therefore our stability is uncertain which means our warrantees may be worthless. In actuality, all of our panels are covered by a blanket Grape Solar warranty AND the original manufacturer warranty. Each panel is individually serialized and traceable with a bar code. The blanket Grape Solar warranty is in place for simplicity and easier customer service. If Grape Solar disappeared tomorrow the warranty would not be affected. It would be as if you purchased the panel directly from the vertically integrated manufacturer. Our stability has nothing to do with the warranty.
- Q: Do you require a minimum order quantity?
A: Due to our constant influx of new inventory and various distribution channels, you can order any number of modules and they will be shipped as needed to your site. Although single panels can be purchased, larger volumes have better pricing.
- Q: What kind of panels does Grape Solar offer?
A: Our current focus is on proven silicon photovoltaic panels. Because of our many contract manufacturers we can offer a wide variety of solar panels. We have everything from 55W to 390W, mono or polycrystalline, black frame, silver frame or frameless. For custom orders we can even offer transparent backing material.
- Q: How do I reach customer and technical support?
A: Call (877) 264-1014 M-F 8:00 – 5:00PM PST. We're available to answer questions about your project, recommend installers or provide general information.
- 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
Photovoltaic systems convert natural sunlight into useable electricity
To guarantee full federal and state incentives are received, installation should be done by a licensed electrician. Contact Grape Solar for a qualified installer in your area.