Solar with battery, loving it!

emmrecs said:

I am NOT an electrician but my understanding is the answers to your questions are Yes, and No, in that order.

The reason is that all Solar PV panels generate DC electricity and the job of the inverter is to convert that DC to AC, which is what is then fed into the grid. I suspect you will not be able to increase the output of your panels without an equivalent increase in the output of your inverter.

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I think you're probably right.

AdamMGEV said:

I'm asking for a quote for another 22 on the North facing back of the house and another 10 on the back of the garage.

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North facing (in the northern hemisphere) is really bad; basically, you will need these panels to be on frames that stick up from the roof at about 45°. Your partner, and perhaps your neighbours and council might have something to say about that.

West facing is OK; east and west facing panels more or less complement each other. One set will produce more during the morning, and one more in the afternoon. Right around solar noon (maybe 1pm if you have daylight "saving") they will both do about the same. You will benefit a little from using two MPPT inputs, otherwise you will have the good string dumping power into the bad string, making less available for use.

I believe you have a single 5 kW inverter at present. Depending on the size of the panels (wattage), I'd say that you are maxing out your present inverter already. So I'm guessing you'd need another inverter to make use of any new panels. The power does have to go through the inverter to be useful, whether that power is used by your loads or fed into the grid.

It's slightly more complex if you have a battery; then you could perhaps use only the half of the inverter that charges the battery. But you didn't mention a battery, and batteries are still quite expensive.

MG Fred said:

Batteries are not a non brainer. Every time I work out the payback period for batteries it comes out at near to 20 years. And then when you‘ve paid them off through savings you need to buy another as it’s worn out. Far better to make use of the free very large battery in your mg4 with V2L adapter. Something I’ll do eventually.

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I agree its a no brainer but in the opposite way to you.

I have a 14kW standalone battery and inverter system. I use Octopus Intelligent tariff which works out like this:-

Cost of system £4200

Peak Rate 29.2p
Off Peak 7.5p

To fully charge the battery 14 x 7.5p = £1.05
Using the battery instead of peak energy saves (29.2-7.5) x 14 = £3.03 saving

Break even point = £4200 / £3.03 = 1386 days or 3.79 years

There is a slight loss during charging and discharging but it's nothing like 20 years. The Battery Life is around 6000 cycles (1 cycle = fully charged to fully discharged) if you did one cycle every day that's 16.5 years. They're deemed to be end of life when their capacity drops to 80%, even at that level my battery will still have a capacity of 11.2kWh, I'll be gone before my batteries die

Coulomb said:

North facing (in the northern hemisphere) is really bad; basically, you will need these panels to be on frames that stick up from the roof at about 45°. Your partner, and perhaps your neighbours and council might have something to say about that.

West facing is OK; east and west facing panels more or less complement each other. One set will produce more during the morning, and one more in the afternoon. Right around solar noon (maybe 1pm if you have daylight "saving") they will both do about the same. You will benefit a little from using two MPPT inputs, otherwise you will have the good string dumping power into the bad string, making less available for use.

I believe you have a single 5 kW inverter at present. Depending on the size of the panels (wattage), I'd say that you are maxing out your present inverter already. So I'm guessing you'd need another inverter to make use of any new panels. The power does have to go through the inverter to be useful, whether that power is used by your loads or fed into the grid.

It's slightly more complex if you have a battery; then you could perhaps use only the half of the inverter that charges the battery. But you didn't mention a battery, and batteries are still quite expensive.

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Yes I have 2 5kw batteries.

On YouTube people were saying g North facing is about 70-80% less affective than South... is that not correct?

As long as its a bright day it will generate well regardless?

johnb80 said:

I agree its a no brainer but in the opposite way to you.

I have a 14kW standalone battery and inverter system. I use Octopus Intelligent tariff which works out like this:-

Cost of system £4200

Peak Rate 29.2p
Off Peak 7.5p

To fully charge the battery 14 x 7.5p = £1.05
Using the battery instead of peak energy saves (29.2-7.5) x 14 = £3.03 saving

Break even point = £4200 / £3.03 = 1386 days or 3.79 years

There is a slight loss during charging and discharging but it's nothing like 20 years. The Battery Life is around 6000 cycles (1 cycle = fully charged to fully discharged) if you did one cycle every day that's 16.5 years. They're deemed to be end of life when their capacity drops to 80%, even at that level my battery will still have a capacity of 11.2kWh, I'll be gone before my batteries die

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Where on earth did you get a 14kWh battery and inverter for £4200??

Or have I misunderstood what you are saying?

tsedge said:

Where on earth did you get a 14kWh battery and inverter for £4200??

Or have I misunderstood what you are saying?

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fogstar for the batteries, amazon for the inverter and Aliexpress for the BMS.

It was a DIY build but in that price was everything including the little shed. I also used a very expensive Victron Inverter. Todays prices have gone down so it should be even cheaper.



Fogstar:

Grade A EVE cells in a prebuilt battery, cased, inc BMS 14.3 kWh £2396
SEPLOS Mason 280L and x16 Grade A EVE LF280K Battery Bundle



Eco Angels:
Givenergy Gen3 Hybrid Inverter 5kW £1458.48
GivEnergy **GEN3** 5kW Hybrid PV Battery Inverter



Apart from an isolator and an MCB thats it, plug and play.

To get similar from Tesla you'd be the top side of £15k

My battery has been switched on since 24th of December (The inaugural daytime load was cooking the Christmas dinner LOL) and apart from 1 minor issue with programming has been completely reliable.

Using the above kit and a sparky to connect into your consumer unit it should be easily done in £4100 at the most.

Thanks very much for all these details, very helpful. I could take something on like this after we move as have a good local sparky for advice, inspection and connection.

It is worth it if I can save this much. Many thanks again.

In the simplest of terms you need Live, Neutral and earth connecting to the inverter and the battery plugging in to the inverter and thats it, press the button and save cash.
Even the application to the DNO is straight forward and you can do it yourself.

AdamMGEV said:

So I got 19 panels and two 5kWh batteries installed for £12.5k and absolutely loving it. 9 panels facing south and 10 facing mostly east and a little south. Generating plenty to power the house and the two cars and exporting some on a bright day. Wish I had done it sooner.

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I totally agree. We have 16 panels, all South and 2x5kWh batteries. For about 3 months of the year (summertime), we are off the grid and charge the car fir nothing. We also get about £800 per year back on the feed in tariff.

I am pro EV, I have 2 of them and I also have home battery storage, I watched this video this morning and it does confirm many peoples fears quite graphically. All of my battery systems charge and operate outdoors and I'm glad I took this precaution, some pretty spectacular footage in there.

Interesting presentation. Unfortunately he doesn't talk at all about different battery chemistries and their relative safety levels.

This is relevant as home batteries are extremely unlikely to be externally damaged.

Thinking a bit more about this:

Another key factor is the probability of thermal runaway without external damage. Clearly this is very very low with modern devices because we all have dozens of such devices in our homes and yet fires are very rare. Manufacturers have made huge strides and newer battery management approaches have dramatically reduced risks.

Yes, cheap poorly made products can malfunction, but even this seems really rare. The consequences of fires is extremely negative to brand reputation.

Obviously there is always the risk of external damage, but again this is very rare, limited typically to car crashes and deliberate demonstrations such as fire safety testing.

Also, this makes me think what would fire safety experts say if petrol or diesel vehicles were introduced as a new technology today? I imagine it would be apocalyptic.

I respect what this expert is saying and clearly he knows more about it than I do - however, if it were as bad as he said, surely we'd all know someone who had suffered a major fire/explosion/smoke event?

I do think he has a good point about older tech and stricter rules for reusing secondhand batteries.

johnb80 said:

.... All of my battery systems charge and operate outdoors and I'm glad I took this precaution, ...

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When you say outdoors....do you mean outdoors or in a building/structure that is not part of the main building.
I ask as considering building a small lean-to shed/outbuilding to house batteries as nowhere decent to put them in the house.

I have my battery outside as I had no room inside the house to put it. I bought a metal shed, and with a bit of DIY, made the depth shallower so that it would sit nicely around the side of the house. All the battery company said was to make sure there were plenty of vents for cooling.

Gomev said:

When you say outdoors....do you mean outdoors or in a building/structure that is not part of the main building.

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In our case, the Tesla home battery is bolted on the outside of the back wall of the house. We put it there as it is north facing (no direct sunlight during the summer), the operational LEDs and hum disturb no-one and the cable run to the electricity meter is short. If the battery did catch fire, there would likely be damage to the outside if the house on that wall, but should be minimal, and certainly less than for an equivalent fire indoors.

Personally, I would not consider putting a house battery of any make or description inside a dwelling, due to the (admittedly low risk) of a fire, but of course they have to be weather proof.

Gadget Geek said:

I have my battery outside as I had no room inside the house to put it. I bought a metal shed, and with a bit of DIY, made the depth shallower so that it would sit nicely around the side of the house. All the battery company said was to make sure there were plenty of vents for cooling.

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Brilliant, this is exactly what I am thinking of doing. My Consumer board would be the other side of the wall a bit further along.

johnb80 said:

I am pro EV, I have 2 of them and I also have home battery storage, I watched this video this morning and it does confirm many peoples fears quite graphically. All of my battery systems charge and operate outdoors and I'm glad I took this precaution, some pretty spectacular footage in there.

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The bits about puncturing and nails etc scared me and reminded me of the time I was in the loft of an older house installing a shower. There was a faint smell like gas. No wonder - the gas pipe supplying the. Boiler had been pierced ( with a nail ? )
It had been undisturbed for well over a year until I found it according to the customer. Whoever did it had smeared the pipe and a spent matchstick with silicone sealant and wedged the match in the hole.
( i’m fairly sure he didn’t use the match to identify the source of the damage he’d caused )

Gadget Geek said:

I have my battery outside as I had no room inside the house to put it. I bought a metal shed, and with a bit of DIY, made the depth shallower so that it would sit nicely around the side of the house. All the battery company said was to make sure there were plenty of vents for cooling.

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You’ve got top vents but I’d have wanted lower ones to encourage a bit of a draught. ( unless the wee bin is hiding one)

Archev said:

You’ve got top vents but I’d have wanted lower ones to encourage a bit of a draught. ( unless the wee bin is hiding one)

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There are lower ones, behind the food recycling bin, and 2 large vents on the front panels.

Gadget Geek said:

There are lower ones, behind the food recycling bin, and 2 large vents on the front panels.

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Aye, mind you, on reflection, I don’t suppose that metal door is hermetically sealed anyway

Gomev said:

When you say outdoors....do you mean outdoors or in a building/structure that is not part of the main building.
I ask as considering building a small lean-to shed/outbuilding to house batteries as nowhere decent to put them in the house.

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This is where my DIY battery is.





The batteries are in the bottom half of the toolstore. I have installed temperature alarms and this is at the opposite side of the house to where we normally inhabit / sleep etc. If it did go up in a bad way it may well set the roof alight but we would have plenty of distance and a clear escape route. Each of the four battery modules comprising of 4 cells has an independent temperature sensor, if the temperature goes outside range allowed the charging and discharging is stopped and the alarm goes off.