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Dr. Steven Hegedus

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Posted By Steven Hegedus 10-18-2023 11:01 AM
Found In Egroup: Everything Solar Forum
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Regarding the recommendation by John Burke to publicize DIY solar module assembly, I feel this would be dangerous and unwise for several reasons.I have respect for Komp's work in bringing PV to developing countries but that is now obsolete. 1. Only modules which pass UL certification can be attached ...
Posted By Steven Hegedus 06-20-2023 02:11 PM
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Bill Your discussion focusses only on efficiency. Yes, Sunpower Maxeon modules had that efficiency several years ago. And they are on n-type Si. The big big difference is that their interdigitated back contact (IBC) modules are also the most costly and complex to manufacture. They have complicated ...
Posted By Steven Hegedus 04-11-2023 05:40 PM
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Yes, Maria Telkes was truly a pioneer. Some might be wondering what was the outcome from all of her research on solar thermal storage? The show said the glauber salts (aka eutectic salts) failed in the MIT Dover house after 2 years, so maybe 500 cycles. 20 years later, Maria was at my lab, the Institute ...
Posted By Steven Hegedus 03-10-2023 10:40 AM
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Felix, How much of the switchgear is unique to PV and how much is standardized for AC connection of any generation source? I assume that all of what you show is on the AC side, right? Anything special on the DC side? Steve ------------------------------ Steven Hegedus Professor and Senior Scientist ...
Posted By Steven Hegedus 01-30-2023 06:42 PM
Found In Egroup: Everything Solar Forum
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Hi Yahuda Yes, that is a big difference. You said the repair tech that Sunpower sent was not able to resolve the problem. What did they inspect to diagnose the problem? Have you contacted sunpower again? Also call your local utility to ask them to confirm their meter reading? Something to check is if ...
Posted By Steven Hegedus 01-30-2023 03:35 PM
Found In Egroup: Everything Solar Forum
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Hi Yahuda Your email is not clear about what 'numbers' don't add up. Solar production, net power consumption, billing charges? I have not seen the data you sent to William, but another thing to compare is what your Electric bill is saying and what the Sunpower system monitor app is saying. They should ...
Posted By Steven Hegedus 01-02-2023 11:00 AM
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Hello I want to share some history from the Sierra Club (SC) on the issue of taking on population limits as an agenda. Consider this as a cautionary tale . I am also a Life Member of ASES and Sierra Club and care deeply for both. The article in this month's Sierra Magazine that James Serene mentions ...
Posted By Steven Hegedus 11-30-2022 01:33 PM
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Bill, I have no idea why this happens. I assume Solar Edge engineers had a reason. Typically when the EV is plugged in and grid is available, the charging power might be 2-3.8 kW from PV and remainder (3-5 kW) from grid. If grid is not available, why wouldn't system allow priority charging of the EV ...
Posted By Steven Hegedus 11-30-2022 10:32 AM
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Hi Good discussion here. I have two comments to add. 1. Yes, charging your EV from local or dedicated solar array is a goal for many. I have a Solar Edge Energy Hub (smart inverter+EV charger+battery back-up) installed at my research lab at the University of Delaware. I have a 5 kW array, 3.8 kW inverter, ...
Posted By Steven Hegedus 10-03-2022 05:32 PM
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Kat and others I have been very pleased with the quality and focus of articles and features in ST in the past few years. In my view it pivoted a few years ago to address interests of professionals more than lay people which I think is right. But you know your membership better than I do. It's one of ...
Posted By Steven Hegedus 07-19-2022 11:23 AM
Found In Egroup: Everything Solar Forum
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I have been involved in solar research and technology applications for 40 years. I have a ready-made platform since as a professor, I teach a class on PV tech, PV systems and also train and mentor graduate students. But two things that we could all do is: 1. Might sound simplistic but wearing a pro-Solar ...
Posted By Steven Hegedus 03-23-2022 12:20 PM
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Bill Fitch makes a good point. There is no single metric of 'best'. A paper from the now defunct Solar Pro magazine (issue 11.1 2018) authored by Paul Grana called 'Design Optimization in Constrained Applications' makes the case that the same commercial rooftop could have three different installations ...
Posted By Steven Hegedus 11-01-2021 09:56 AM
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Hi Bernard I am studying a fixed tilt bifacial array installed this summer at my lab at U Delaware. We have found that the reflectivity of the ground cover (white, silver, black tarps or gray gravel) does have a big impact on sunlight incident on rear. But it does not necessarily translate into increased ...
Posted By Steven Hegedus 08-03-2021 09:27 AM
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I assume that you will be installing a battery backed system to store daytime energy for evening use? I don't know anything about SolArk inverters. But I have SMA battery backed system and Solar Edge Energy Hub system installed in my lab. Both have a 10 kWh LG battery. We have only have them each for ...
Posted By Steven Hegedus 03-25-2021 08:29 AM
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Thanks for replies. I determined that both inverters have the control functions available but they are not certified by Sunspec. I was able to access them eventually. This request is not longer active. Steve ------------------------------ Steven Hegedus Professor and Senior Scientist University of Delaware ...
Posted By Steven Hegedus 02-18-2021 08:33 PM
Found In Egroup: Everything Solar Forum
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Hi I am looking for residential inverters < 5 kW that allow curve-based controls like Volt-VAR and Volt-Watt. Doing research on comparing curve based control to preset automated response. Typically they use Modbus for communication but could be other methods. I had assumed that any inverter meeting ...