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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    Dear Esteemed Community,

    Ramping up the resilience factors....what do folks think about the wisdom of plug in solar?
    Thanks, carol
    • CommentTimeMar 18th 2020
    Assuming you mean https://www.pluginsolar.co.uk/ I personally would give them a miss. Whilst wiring an FCU (fused connection unit) to an existing ring main is indeed possible to DIY, it is not IMHO a sensible way to connect a PV system. I would rather see a PV system connected to its own new circuit on the consumer unit in the traditional way, and that is not DIY.
    • CommentTimeMar 18th 2020
    Sounds crazy - what wd be the effect of generated power applying voltage to the house ringmains if e.g. no electrical resistances were on-load in the house? The power wd go nowhere, so wd the solar panels just get v hot?
    • CommentAuthorgoodevans
    • CommentTimeMar 18th 2020
    I think in the above scenario the generated power would go to the grid, unregistered by a standard meter - unless there is a power cut, in which case the solar should disconnect from the mains to prevent electrocution to those working in the house or the grid.

    In the event that the panels are just in the sun - disconnected from everything I suspect they must get hotter than if the power was taken away.

    Probably a better way to think of it is that drawing power from the panels actively cools them.

    Just a guess - the only other way I can imagine a balancing of the power is if the reflectivity of the panels change depending on load.
    • CommentAuthorbhommels
    • CommentTimeMar 18th 2020
    It is not SO different from how a normal PV array is connected.
    Instead of having its own spur/circuit, it is now plugged into a high rated circuit that is already there. The inverter will not behave differently than any other grid-tied inverter will do, and excess power is either used in the home or pushed back into the grid. In case of a power cut the inverter will shut down, and no current will be drawn from the panels.
    The panels themselves will just dissipate away the imposed voltage, getting hotter (than normal) in the process.
    Carol, I was recently looking at fitting PV and I am starting to wonder if solar-panels-on-houses are going the same way as wind-turbines-on-houses (remember them?!).

    PV can be installed a lot more effectively if it goes in a large scale solar farm instead of on a house. The farms have big economies of scale, no compromises on orientation or shading or grid connection, easy access from ground level, and hopefully no neighbours to upset!

    Even doing it all DIY with cheaper components, I couldn't make the cost work out to retrofit it on my roof.

    The mains-connected systems cut out for safety if there's a grid power cut, there's 12volt systems available if you want off-grid resilience!

    Hi Tom, wot GE &bhommels said. If (any) PV panel is not connected to a load, it behaves like a painted sheet of glass when left out in the sun - absorbs or reflects 100% of sunlight as heat, instead of about 80% which it would normally when connected. So will get a little warmer.

    Hi DJH, I agree that the PV should be on its own circuit. If there is a fault current in the socket circuit, the mcb should see that current and disconnect. However if part of the fault current is coming in from the PV halfway round the circuit, the mcb cannot sense that.
    • CommentTimeMar 18th 2020
    Posted By: fostertomSounds crazy - what wd be the effect of generated power applying voltage to the house ringmains if e.g. no electrical resistances were on-load in the house? The power wd go nowhere, so wd the solar panels just get v hot?

    As others have said, it doesn't work like that, Tom. Wherever the power is connected it will be used by anything close by and anything left over will find its way back out through the meter to the grid and be used by others. What the meter registers, if anything depends on the particular meter design and settings. It shouldn't show any export on any consumption register though.

    The reason for connecting it separately is for safety as WinA says.
    Thank you each and all....It's helped us to decide not to go there!
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