It occurred to me that with the price of electricity soaring to new and higher levels it must surely be worth the cost of fitting solar panels. I do find that finding a reliable, trusted and non-biased source of information is very difficult. A search request using Google turns up so many commercial and biased sites that iti's difficult to sort the sheep from the goats. Can anyone on this NG point me in the right direction? I would be grateful. Peter
Solar Panels and electricity cost
Oct 17, 2021
Last reply: 4 years ago
81 Replies
For starters ...
How much electricity do you use per day? how much of that while the sun is shining?
Click yourself on the map, and pick a typical (?) 3.6kWp system, divide the yearly PV production by your price per kWh
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Why did I say divide? multiply ... and that's how much it'd be worth to you if you could use it allduring daylight, if not they it's worth a pittance to export it, or you have to pay for batteries to store it until later
only if you actually use the electricity generated
the amount that the companies now pay for electricity that you feed to them is a pittance
what's wrong with this:
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you don't need to use it BTW, it will tell you that the returns are now pitiful
This is a bit less critical nowadays with the take up of batteries to charge from the PV. £8k would get 4kW of panel installed with a 6kWh battery which ought to provide a small household needs for 9 months of the year.
Whether that is a cost effective use of the investment is another matter, especially for retirees.
Maybe ... ish.
In summer the batteries will only be able to store half the panels output, and in winter the panels will only be able to charge the batteries to two thirds, and there'll be a couple of goldilocks months, so it still depends how much you can use while the sun is shining
So I couldn't take a shower or cook or do a wash or use the dishwasher at night?
Bill
"with a 6kWh battery "
so enough for a shower OR a wash OR doing the dishes, but not all three.
>
Well I can't speak for you, but an electric shower takes me about 1kWh, a run of the dishwasher likewise. If you have a hot water cylinder you can heat it when you have excess power which would also cover uses like hot water for the sink or running a bath.
Theo
But then it becomes a constant juggling and forward planning nighmare. Most people try to escape that.
But for a decent shower it'll need power of at least 10 kW. An inverter sized for 4kW of panels and 6kWh of batteries, will likely be around 5kW, in which case only half the energy will come from the battery.
It can only add to the value of the property, so one way or another it probably is cost effective. Just look at how the price of
2nd hand cars from 1 to 3 years old has jumped in the last 18 months. No-one would have predicted that 2 years ago.
But solar water panels are effective even when it is overcast, so a combination of both types and a HW cyl with dual coils, and some form of storage battery (which could even be your EV) would massively reduce your needs for external power. Just not
100% effective at being off grid.
Why would it? Few people are totally off grid. It?s not like all the electrics in the house die when the battery is depleted.
Tim
I think you?re mixing up kWhr, a unit of stored energy, with kW, a rate of energy delivery. Just because a battery has a 6kWhr capacity doesn?t mean that it can?t deliver more than 6kW.
Tim
I didn't come to that conclusion. Andy's assertion is that an inverter sized for his solar and batteries would be 5kW, and therefore at best only supply 1/2 the poser of his 10kW shower.
Taking more than 'C' out of a battery is not ideal.
Err no.
It's not the battery that's likely to be the limit but, as I said, *the*
*inverter* you could fit a higher power model, or multiple in parallel to run showers, ovens and washing machines galore.
Effective at what level, compared to full sun?
The solar water panels on a new house near here, were very effective at melting the snow deposited on them after a storm.
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