DIY Solar PV in theory

[Benway]

Energy prices are going crazy so I've been looking at DIY Solar PV. It seems a bit of a no brainer.

You buy a grid tied kit. Fill out a G98 form and send to the DNO (if under 3.6Kw), I think DNO things get complicated after that. Get it installed (as per regs/etc) connect up to a spare way in your CU and you're away!

I'm not bothered about getting paid for anything I supply back to the grid. In the future if I wanted to I can connect a battery up. I have a flat roof available so less chance of falling off and killing myself.

What am I missing?

Just pulled a random add of the internet, not saying this is kit I would go for:

Plug-In Solar 3.52kW (3520W) DIY Solar Power Kit with Renusol Console+ Tubs (for Ground or Flat Roof) | Plug In Solar

 

[Mr Chibs]

I’ve no experience of solar on houses, but at a quick look, this kit looks like it’s for a feed-in... doesn’t look like you could use the electric, as you aren’t bothered by Selling it back.

think you need some form of inverter/batteries etc to be able to use the created power.

will watch this post, for more informed replies Than mine

 

[SUNRAY]

I confess I've started reconsidering...

 

[Benway]

The Enphase Micro-Inverter
This Plug In Solar Kit is supplied with G98 certified Enphase IQ7 Micro-Inverters. The Micro-Inverters convert direct current (DC) produced by the solar panels into alternating current (AC) for use in your home

I’ve no experience of solar on houses, but at a quick look, this kit looks like it’s for a feed-in... doesn’t look like you could use the electric, as you aren’t bothered by Selling it back.

think you need some form of inverter/batteries etc to be able to use the created power.

will watch this post, for more informed replies Than mine

 

[Mr Chibs]

Thanks for correcting me.

 

[flameport]

What am I missing?

For the item linked to, you can't subsequently connect battery storage without buying a new inverter, which will be £1000+ on top of the battery costs.
All it can do is what's described - generate electricity which can either be used at the time it's generated or it will go back into the grid.

Good if you can use the electricity when it's generated. Fairly useless otherwise.

If you are looking to add battery storage later, buy a hybrid inverter to start with.
The shading issues described in the linked item can be avoided by the use of those micro inverters they are selling. They can also be avoided by locating the panels where they won't be shaded, which should always be the first choice.

 

[lostinthelight]

If you mount the panels below a certain angle they loose the self cleaning effect so handy to have them accessible for easy cleansing . Also look at bifacial ones which generate rays reflected from below

 

[SimonH2]

I’ve no experience of solar on houses, but at a quick look, this kit looks like it’s for a feed-in... doesn’t look like you could use the electric

Incorrect.
With a grid tied system, the inverter merely sends power back up its connection to the mains grid - it doesn't know where that lecky goes to. If you are using more power in the house than is being generated, then the difference will come from the grid and you'll be charged for it; if you are using less than is being generated, then the excess will flow back out through your meter, and if the meter is the right type/setup correctly then it will meter the net outflow.
Getting the best return means being home and using lecky when the sun is shining. Otherwise you expert that power and get a pittance (or nothing) for it, then import lecky at the normal price when you are home and running stuff.

If you have a hot water cylinder then it's possible to configure a system to divert power into the immersion heater rather than export it - that's a fairly cheap and easy way to store some energy and will reduce your hot water costs. Otherwise you need a battery system and that's going to considerably add to both your capital and running costs.

 

[john4703]

Ia agree with SimonH2 Heating water is a good way foreards. I've been thinking along the lines of a solar panel and a couple of storage heaters. They don't store electricity but do store heat and let it out slowly. I'm not sure if it is worth the expense of all the instalation but if energy prices keep rising who knows.

 

[SimonH2]

Storage heaters are ... how do I put this without breaching forum rules ... "really rubbish".
We had them at my last employer - too much heat in the morning, not enough in the afternoon, and to get the best result you need to predict requirements and adjust them each day to suit what you'll want for the next. If thinking of them being charged from solar - think about when (time of year) you get the most sunlight, and when (time of year) you want heat.

 

[JohnD]

will reduce your hot water costs

unless you have the opportunity to heat your HW cylinder with a gas boiler, because the cost of energy from gas is so low that any savings after buying an immersion controller are trivial or negative.

 

[oldbutnotdead]

unless you have the opportunity to heat your HW cylinder with a gas boiler, because the cost of energy from gas is so low that any savings after buying an immersion controller are trivial or negative.

Mmmm. The kit linked to is £4200 inc VAT. At my tariff after April 1 that would buy me 15,400-odd kwH of electricity (about 5 years worth on current usage).
We can safely assume that the price of energy is only going to go up.
I do have a convenient energy sink (the thermal store)- however, this can be heated by the woodburner (cost per kwH difficult to determine, it is hard work chopping wood up and the chainsaw uses petrol and oil so it isn't free and it isn't good for the polar bears) or heated by gas (post April 1 price is doubling to 7.225p/kwH and suddenly with that number payback date for a PV array has gone past the point where I expect to be among the living).

So in my personal world to make the numbers for a PV array work I'd need a controller that could (when PV was generating) divert enough energy from PV to house to keep import at zero (so all the background load- fridge, broadband modem, various wifi toys, burglar alarm, freezer, washer, telly etc etc) was powered by PV, anything left over would go into the battery (so yes I need to add £1k to the install cost), when the battery is fully charged any surplus goes into the thermal store and the grid gets nowt. Does such a toy exist?. Payback after 5 or 6 years is not a bad investment, especially if inflation stays at its current rate (which will bring payback forward considerably)

 

[JohnW2]

... Payback after 5 or 6 years is not a bad investment, especially if inflation stays at its current rate (which will bring payback forward considerably)

Maybe but, as I've just written to you in another thread, even if your figures are reasonably realistic "payback after 5 or 6 years" is another way of saying that for 5 or 6 years you will be financially worse off than you would have been without the PV - which, depending on ones age and 'circumstances', might not be such a welcome situation.

... and don't forget that the financial benefits don't go on 'for ever' after you have reached that 'break-even point' (after 5-6 years or whatever), since it's probably not all that many years after you reach that point that you may well have to replace most/all of the PV system, putting your financial clock back to square one!

Kind Regards, John

 

[oldbutnotdead]

Yes I saw the other thread and yes in purely financial terms the numbers don't stack up. And in benefits to the polar bears I'm not 100% convinced that the energy debt incurred by making and transporting the panels will ever be repaid. Stuff to contemplate....

 

[AndyPRK]

One storage heater in the living room may work.

Store it up during the day, and let the heat out in the evening.
I guess there are only about 3 months of the year this would be worth while
but would add a bit during winter