COMPANY I OVERVIEW later on.
The flashing strip includes pre-assembled bolts that “stick up” from the roof surface. The inter-bolt spacing is matched to align with the inter-hole spacing on the aluminium support structure mentioned earlier. Once the flashings are in place the module/ support structure is lowered onto these bolts, a washer and nut are used to secure them to the roof via the flashing strip as shown in Figure 7. Module racking and mounting hardware described earlier in this article contributes approximately $0.44/ Watt
to the cost of a US residential solar installation. The value- add of module-integrated mounting, such as proposed by Giga Solar, is expected to save 50% or more, eliminating a minimum of $0.22/Watt from the cost of residential mounting hardware today.
Figure 4: 2, 260Wp Giga Solar modules installed on a test roof
lbs. and produces the same power. The combined weight of a 60-cell Giga solar module plus support structure is 27 lbs, still a 35% weight reduction from the traditional glass solar module (alone). Heavy modules lead to higher transportation costs, longer installation time, potential installer injury and higher roof loads.
The module support structure includes pre-drilled wire management holes with silicone grommets. Figure 5, below, shows a junction box and jumper cables that run through the integrated mounting support structure. This solution prevents conductors from being directly exposed to UV and the weather, as well as to (hungry) animals. It also eliminates any chance that the conductors will become loose and sag onto the rooftop where they could wear prematurely. The inter-module connection (see Figure 6,) is made at the edge of the module support structure where the MC3 or MC4 connector passes through the aluminum wall to the adjacent module. This design provides a true plug-and-play installation.
Giga Solar benefits
The benefits of Giga Solar’s technology can be grouped into three main categories – hardware cost, installation labour cost and design flexibility. The Giga Solar product is designed to make every installation quick and simple.
There are only two main components to attach to a composition shingle roof:
1. The roof flashing, and 2. The integrated module/support structure
The Giga Solar aluminium roof flashing is similar to an EcoFasten flashing but is supplied in long strips. These long strips come with pre-drilled holes on 16” or 24” centres for attachment with lag screws to the underlying rafters. Once the first rafter is located, the flashing is placed and attached, providing a template for additional rafter-attachments through the pre-drilled holes. This saves time during installation and increases accuracy of locating rafters. The combination of light weight and direct mount allow for approximately 20-30% fewer penetrations than current systems, saving labour and decreasing the likelihood of a leak
Design flexibility
Standard crystalline solar PV modules are typically either 60- cell or 72-cell configurations. Giga Solar is currently evaluating modules larger than 72-cell to allow for greater design flexibility (and lower BOS costs). Giga Solar modules are feasible in large sizes because of their lightweight design. With the ability to
Labour costs From a labour standpoint, the time that it takes to install a residential solar system depends on: £ System size £ Roof complexity £ Hardware design £ Skill level of the installation crew
The Giga Solar system is designed to go onto the roof much quicker than the existing systems. Today’s labor costs for US Residential PV systems is in the range of $0.51 to $0.55/Watt . Although Giga Solar cannot provide actual installation cost data at this point in time, the company believes that it’s simplified, direct-mount system can reduce installation cost by as much as $0.35-$0.40/Watt.
Summary of cost savings
The combined savings from hardware and labor for the Giga Solar system in residential rooftop installations could therefore be as much as $0.55 -$0.60/Watt. On a 6kW system these savings amount to $3,600 and helps to bring the total installed system costs that much closer to the DOE SunShot goals for 2020.
Figure 5: Giga Solar JBox with electrical conductor management Issue IV 2014 I
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