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Showing content with the highest reputation since 01/23/2024 in Posts

  1. 1 point
    I've said before that installing PV (photovoltaic) panels is basically paying for the electricity cost for the next X number of years up front and I still stand by this view as the area that is possible to use for install of PV panels in a landed house is quite limited. Anyway I've just had my grid-tied PV installation commissioned last week and officially is generating electricity off my roof and exporting excess back to the grid. Here's some of the key takeaways in my PV installation journey. 1. research, research and do more research, if you have the time and interest in it. Cos it's better to have some basic knowledge rather than relying on the contractor and believing everything they say. 2. roof profile matters as well as the direction of your house's facing. it's best to have a relatively flat roof as PV panels will have the maximum efficiency when it's almost at full flat facing to the sky. But not to say that angled roofs cannot install panels as well but really depends on your house facing direction. Do note that due to rotation of the earth, the area where the sun hits your roof will shift a bit as well through the year. If your house is north south facing (this is commonly mentioned as the ideal facing due to wind direction), you will also be able to get full sun throughout the day since the run rises from the east and sets in the west. For my house, it is facing almost east west so there's a part of my roof which does not get sun in the afternoons due to the sun getting lower as it starts to set. However I also installed panels on that part of the sloping roof since it gets sun during the mornings and the early part of the afternoon. Same for my car porch roof which I installed panels as well which will get the sun only just after around noon. While efficiency for these panels which does not get full sun throughout the day is lesser, they still generate electricity at certain times of the day so these panels increased my PV array by another 30 percent which will translate to a faster ROI period. One contractor told me they don't bother to do on sloping roofs since the efficiency is bad but to me it don't make sense since the sloping roof still gets light. While this may be true as a single panel in the array can affect the entire array's performance, I'm the paymaster so I decide where I want to have the panels installed. 3. Type of roof material matters. If you have a metal roof, it will be easier to install since the panels will be installed to a stainless steel structure which is clamped to your roof panels. But if you have tiled roof, then it will be more troublesome as drilling will be involved which is a potential for leaks. One neighbour had tiled roof and installed PV panels which led to leaks. End up they also had to replace the roof as well to sort out the leaks. For RC roof, the steel structure for the panels will need to be installed by drilling to your RC roof which will mean the waterproofing membrane will be broken and potentially lead to leaks in future. 4. Get quotations from as many contractors as you can for price comparison and then do a research on the parts they propose for your installation. Different contractors will use different parts and the specifications and warranties also vary. The panels available in the market since late 2022 ranges from about 400Wp to 435Wp (size about 1.1m by 1.8m) depending on the brand and model. Panel technology is always evolving and back in 2017/2018, another member had a proposal for panels which generates about 260Wp for similar sized panels. With this said, one can see that the panels performance improved by about 60 percent (from 260Wp to about 420Wp) just in about 5 years. This will also imply that the ROI will be shorter since the panels can generate more electricity. Also panel manufacturers give power performance warranty as well as panel workmanship warranties for up to 30 years now. For PV inverters, I used Huawei's inverter which comes with a 10 years warranty. The funny thing is that one contractor only stated a 5 year warranty for the inverter in his proposal even though other contractors indicated 10 years for the same model inverter. 5. If you're renovating/rebuilding your house now, I would suggest doing it together to avoid any inconvenience in future. If you're not sure if you want to do now but maybe in future, then provide for either the electrical conduits for pulling cables from your roof to the DB or install a 3 phase isolator (connected to DB) near your roof area and reserve a space for the PV inverter to be installed. This will avoid needing to drill holes in your house to pull cables. Also if you're doing it later, you will also need to pay for scaffoldings to be erected so that the panels and/or cabling can be installed. The scaffolding cost will be another few thousand dollars which can be saved if you're doing the panels when your house is undergoing construction since the scaffolding is already there. 6. Authorities approvals. When doing grid-tied PV installation, SP Group will need to be informed and the normal electricity meter changed to a two way meter so that any electricity export can be tracked. The meter will cost $$$ so doing it during the construction phase if you're upgrading from single phase to 3 phase power will save you some money from needing to pay for the meter twice. Also the lead time for SP to install the meter and do inspection is also quite long (about 2 months from initial submission) so if you're going to do an add on of PV panels, tell and chase your contractor to submit it early. My project was delayed by months because the contractor failed to submit the paperwork to SP early even though I had kept mentioning many times that they need to do it early to reduce the delay and wait times. If your house is a 3.5 storey or 2.5 storey with mezzanine (aka, physically has 4 or more floors), then there is a need to inform SCDF as well for fire safety clearance. During construction, this will be done by your QP. But if you're doing PV panels afterwards, then either you need to find a QP or your contractor will charge you to do the submission for you. Please do not try to avoid doing this submission as there may be issues with insurance claims in the event something happens after you install the PV panels. Even if the cause is not due to the PV panels, the insurance company may refuse the claim since you have done modifications to your house without the approval of SCDF.
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