Hi Albert, just to add to some good suggestions already given:
Re: your passive house, there are many good brands of solar modules (panels). There are two main sizes, residential modules typically have 60 cells, have black anodized frames, and are approx 39.5in x 66in, and commercial modules typically 72 cells, have clear (aluminum colored) anodized frames, and are approx 39.5 in x 79in. If you are building a modern home, the commercial modules may be an option if you want a more industrial look, and they cost less per watt. I like REC Group, for their quality, performance, strong warranty, and great value. Whatever brand you choose, make sure they have been around for a while, since a warranty is only good if the company can back it up when the claim comes.
Your choice of a metal roof is excellent, IMO. If it is a standing seam roof, then the array structure can be attched using seam clamps, like those from S-5. If it is a corrugated or trapezoidal roof that is attached with penetrating screws then make sure your installer selects a good quality penetrating mount with integral elastomeric or butyl sealant. Also, since you are building the house, make sure the roof substructure is constructed properly for the addition of the solar array. Standard metal roof installations may not account for the higher uplift forces that occur when strong winds get under the array. Make sure the underlayment is installed to the rafters with extra screws. Make sure any purlins or 2x furring is attached firmly with extra screws to withstand the uplift. If standing seam, then double the number of clip attachments. If screw-down/corrugated, don't increase the screw count, the solar attachments will add to what is there. If roof slope is 4:12 or lower, I usually don't have any issues walking on new metal roofs. But greater than 5:12 and higher will likely require footboards to install. Also, if there are East-West Purlins, typically the panel orientation needs to change to landscape, and the rails (if used) will go north and south up the roof. For standing seam, the panels will typically stay Portrait mounted.
Another choice you or your installer will need to make is the type of inverter. If you have any shading or multiple roof surfaces that face different directions or with differing slopes, then optimizers (like a SolarEdge system) or microinverters (like enphase) are usually the best options. If the roof area is such that staying within the fairly narrow design constraints required by a conventional string inverter is not an issue, then you might save a little money by going with a string inverter and rapid shutdown devices.
As far as failure modes of panels, they really should not fail of properly handled and installed. For optimal electrical configuration, your installer should hopefully try to do that for you, but in general, the higher the voltage of the array, the more efficient the system. SolarEdge systems run at 380VDC, and so if each string is carried from the roof to the inverter location using 10AWG wire, you will have negligible wiring losses. There is usually a little more loss in a microinverter system like enphase because it operates at 240VAC. Conventional string inverter based systems can be designed with strings at 450V to 500V or even higher on cool days.
What risks to avoid? Make sure the company you go with is good at designing solar generation systems. Decide ahead of time if you might want to add an electric vehicle charger, or battery storage someday. This might change your choice of inverter model. Also, review your solar and any backup power needs before before your main electric panel is chosen and installed. If you need a large array, the system will need to be connected via a line-side connection. A system with a 7.6kW inverter or less can be installed on a back fed breaker in a 200A distribution panel. A number of inverter companies now offer equipment that includes whole-house backup capability, and some forethought about batteries and EV charging and circuits to be backed up can prevent lot of rework later. Also, think about the wiring paths from the array to the inverter location so you can pre-install during the build any conduit needed for the best aesthetics.
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Ken Nadsady
AviSun Renewable Energy
Hudson OH
Knadsady@avisun.net------------------------------
Original Message:
Sent: Mar 02, 2021 09:33 AM
From: Albert Bell
Subject: What kinds of resources are you interested in receiving from ASES?
I am building a passive house which will be certified by PHIUS PHIUS Home Page to the 2021 standard. What brand of solar panels should I install? Is there an independent testing agency? I am mounting the panels on a metal roof, what is the best color. What are the potential failure modes for the panels? Is there an optimal electrical configuration for a group of panels? What risks should be avoided?
I think there needs to another separate discussion around a robust relationship with the electrical utility. I believe residential customers should be encouraged to over produce on an annual basis. I think the utilities should be fairly compensationed for transmission and distribution networks. The system should be fair for all and encourage residential customers to do their share to improve the environment. Currently, in Southeasthern Michigan, DTE and Michigan Legislature prohibit production above annual needs. This nation needs to move to a sustainable energy future ASAP. All the arrows must be aligned. ASES through a discussion could develop a proposal which could then be presented to governments at all levels for implementation.
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Albert Bell
Professor
University of Michigan
Birmingham MI
ahbelliv@umich.eduahbelliv@umich.edu
Original Message:
Sent: Mar 01, 2021 03:06 PM
From: Terrell Cato
Subject: What kinds of resources are you interested in receiving from ASES?
Hello ASES online community!
In order for everyone here to get as much as possible out of ASES and the community, I would like to know what kinds of resources you would like to see from us? Is there something not discussed that you would like to see brought up? What kind of information are you most interested in? IS there an area in the solar or renewable energy sector that needs more attention? What topics do you want to see? Some examples links:
Would you guys like more of anything like the above, or something totally different? Let me and ASES know!
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Terrell Cato
Wilmington DE
tcato@ases.org
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