DIY Solar PV Battery storage for my house

[Revolvor]

Some advice please.

I already have 3kW of Solar on my house and am considering having battery storage installed.

We currently generate about 3300kW per annum, which almost exactly matches our consumption from the grid.

There seems to be shortage of installers (and batteries) so I was wondering if it would be possible to install my own system, and just get the final connections and certification done by an electrician.

I was thinking along the lines of a large Victron Multplus charger/ inverter (or equivalent) and a large number of Lithium batteries.

Would this be feasible? I'm aware of the requirement to isolate the system from the mains if there is a power outage. I'm not sure quite how my existing panels/ Inverter would interact with another inverter and batteries.

What other things need to be considered?

How would the 13.5 kWh from a (for example) Tesla Powerwall translate into the number of 200 Ah lithium batteries?

Am I just talking rubbish?!!

 

[Lenny HB]

Raul is the man to ask.

 

[Bessy765]

I am just going trough the same process myself. Looking at 4.1 kWh = 12 panels in 2 rows of 6 placed of my garage flat roof. And a 6.2 kWh battery. I think the Tesla Powerwall needs a minimum solar panels to work. I have to apply for planning and building control. Rules are different for flat roofs.

 

[jongood]

Some advice please.

I already have 3kW of Solar on my house and am considering having battery storage installed.

We currently generate about 3300kW per annum, which almost exactly matches our consumption from the grid.

There seems to be shortage of installers (and batteries) so I was wondering if it would be possible to install my own system, and just get the final connections and certification done by an electrician.

I was thinking along the lines of a large Victron Multplus charger/ inverter (or equivalent) and a large number of Lithium batteries.

Would this be feasible? I'm aware of the requirement to isolate the system from the mains if there is a power outage. I'm not sure quite how my existing panels/ Inverter would interact with another inverter and batteries.

What other things need to be considered?

How would the 13.5 kWh from a (for example) Tesla Powerwall translate into the number of 200 Ah lithium batteries?

Am I just talking rubbish?!!

Im also quite interested in this. 7kw on the roof and a wife with an electric kiln. I wonder if hou need to buy a powerwall etc or just use a pallet of FLA batteries and a good inverter. Ok I know LifePo4 will last longer but ?x the price?

 

[Revolvor]

Raul is the man to ask.

Yes I know, but I thought it too presumptuous to tag him!!

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[donkey]

Not got a lot knowledge regarding house solar. If the amount generated equals the amount consumed, why would you want to store any? Or is it just me?

Geoff

 

[Richard n Ann]

Not got a lot knowledge regarding house solar. If the amount generated equals the amount consumed, why would you want to store any? Or is it just me?

Geoff

For at night?

 

[Bolti]

Not got a lot knowledge regarding house solar. If the amount generated equals the amount consumed, why would you want to store any? Or is it just me?

Geoff

Because if not used instantly goes to the grid then the op has to buy back when required.

 

[Richard n Ann]

Because if not used instantly goes to the grid then the op has to buy back when required.

Keeping the grid involved would presumably incur standing charge though.. I notice they've increased it to combat people trying to save money by using less

 

[Revolvor]

Keeping the grid involved would presumably incur standing charge though.. I notice they've increased it to combat people trying to save money by using less

Yes, you have to commit to being totally grid-free, or pay the daily charge.

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[mikebeaches]

I believe the energy supplier Utilita may still have one or more standing charge-free tariff(s).

 

[Bessy765]

https://www.spiritenergy.co.uk/hubfs/Website%20downloads/Info%20Packs/Spirit%20Energy%20Tesla%20Powerwall%202%20Buyers%20Guide.pdf?utm_campaign=Tesla%20Powerwall&utm_medium=email&_hsmi=99967197&_hsenc=p2ANqtz-8KW7fQxoAZvMAH6Ud5-6KJWb4YFoUPrcw6VzE4H30Y0jNOIEkdY4usRKWXMU7DmU4cBRGEcFcnqkwFS2ggxo7_YOiRQg&utm_content=99967197&utm_source=hs_automation

 

[mikebeaches]

We had an array of 20 panels, 13 (2 x 6.5) kWh lithium battery storage and a smart hybrid inverter installed in February.

Seems to be working well, saving us money and earning a few bob too.

I obviously did some research beforehand and for me the battery storage is the real game changer.

But don't really consider myself a technical expert on the subject...

 

[donkey]

Because if not used instantly goes to the grid then the op has to buy back when required.

So the OP's statement that: Amount generated = amount used, does not result in a zero charge?

Geoff

 

[Wack]

We had an array of 20 panels, 13 (2 x 6.5) kWh lithium battery storage and a smart hybrid inverter installed in February.

Seems to be working well, saving us money and earning a few bob too.

I obviously did some research beforehand and for me the battery storage is the real game changer.

But don't really consider myself a technical expert on the subject...

Could you clarify the saving us money and earning a few bob bit please

How long before the savings cover the cost of installation , and are there any annual maintenance costs , cleaning solar panels etc

Thanks

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[Raul]

In your particular situation, with the 3kwp already installed, it’s the chance of the Tesla being compatible with what you have. Otherwise another hybrid inverter needs adding to work with HV battery.
On the other hand, you could go with a multiplus 2 that is already accredited in UK for energy storage and will work quite happy with a 48v LV battery coupled to any existing inverter. And it will be configured in ESS to comply with the islanding regs. A LV battery like pylontech it’s popular, even the new modules US5000 that have 5kwh capacity. Saying that, pylon has rubbish customer support and their firm aware has problems for some.
Another fantastic system that it’s been tested and works well is BYD batteries. They come in modules of 3,5kwh and stack up to 7 I think for each battery base. You can scale this right up to 44kwh.
When my lead it’s had enough, it will be replaced with BYD LV. I have taken part at a install in the past with BYD. I was impressed the ease of configuring everything worked straight off, and it’s been there over 6-7 years now with no complains. It was a 10kwh BYD cabinet with 4 modules. They have been superseded to better modules now.

 

[Raul]

So the OP's statement that: Amount generated = amount used, does not result in a zero charge?

Geoff

It doesn’t, it uses grid power when solar is off to amount to the sum, but he is not using all his generation. By introducing batteries in the system, you get to keep what you harvest, and change time of use.

 

[donkey]

It doesn’t, it uses grid power when solar is off to amount to the sum, but he is not using all his generation. By introducing batteries in the system, you get to keep what you harvest, and change time of use.

But at an enormous cost surely. Does he not get reimbursed for the power generated that he does not use?
Geoff

 

[Revolvor]

So the OP's statement that: Amount generated = amount used, does not result in a zero charge?

Geoff

No, because the power is being generated during the day, and either used at night or returned to the grid On a good day in the summer we generate 20kW, but don't use it all, even with an immersion heater, boiling kettles, dishwasher, etc. We do however receive about £1600 a year from the Feed in Tariff.

It's a crazy system where I get paid approx 50p for every kW generated, whether I use it, or return it to the grid - but I'm not complaining!

 

[Revolvor]

But at an enormous cost surely. Does he not get reimbursed for the power generated that he does not use?
Geoff

I get reimbursed for all that I generate, even if I use it!

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[Raul]

But at an enormous cost surely. Does he not get reimbursed for the power generated that he does not use?
Geoff

If he gets reimbursed for the feed in depends when he did it. There is no feed in now, and the cost for batteries it’s not enormous. It does depend on each individual user and it will influence the ROI. Some time ago storage used to be prohibitive with no ROI. Electricity will only go up.

 

[donkey]

If he gets reimbursed for the feed in depends when he did it. There is no feed in now, and the cost for batteries it’s not enormous. It does depend on each individual user and it will influence the ROI. Some time ago storage used to be prohibitive with no ROI. Electricity will only go up.

Thanks, I am getting a better picture now.

Geoff

 

[Raul]

No, because the power is being generated during the day, and either used at night or returned to the grid On a good day in the summer we generate 20kW, but don't use it all, even with an immersion heater, boiling kettles, dishwasher, etc. We do however receive about £1600 a year from the Feed in Tariff.

It's a crazy system where I get paid approx 50p for every kW generated, whether I use it, or return it to the grid - but I'm not complaining!

In that case, consider yourself a lucky man. Many wish to been grandfathered in the old deal where you get paid to generate and to feed in.
In you rare situation, I would not consider a battery, you got one, the grid and a good one. You feed in get paid and covers over your consumption.
If you whant as a enthusiast to add a battery, I would go for a small 3-5kwh as a UPS if you have grid outages. If that’s not a issue, then save the battery money, or spend it in insulation.

 

[dunnah01]

I'm intending to fit a solar diverter to heat a tank of water for storage. Much cheaper than batteries as a half way house. My inverters need to be grid tied to work - the phasing of the mains electric needs to be matched but due to limited insulation in the house during refurb any feed in type tariff is non existent

 

[jongood]

So the OP's statement that: Amount generated = amount used, does not result in a zero charge?

Geoff

Really??

That is the point of batteries, so you can use your own power.

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[jongood]

No, because the power is being generated during the day, and either used at night or returned to the grid On a good day in the summer we generate 20kW, but don't use it all, even with an immersion heater, boiling kettles, dishwasher, etc. We do however receive about £1600 a year from the Feed in Tariff.

It's a crazy system where I get paid approx 50p for every kW generated, whether I use it, or return it to the grid - but I'm not complaining!

We re a later joiner so only 5p. Pretty annoying when they re putting their charges up massively.

 

[Raul]

We re a later joiner so only 5p. Pretty annoying when they re putting their charges up massively.

So yours will make sense the battery. The OP is grandfathered in the very first old deals, and he’s most rewarded if he feeds in ALL the production.

 

[Revolvor]

If you want as a enthusiast to add a battery, I would go for a small 3-5kwh as a UPS if you have grid outages. If that’s not a issue, then save the battery money, or spend it in insulation.

Thanks for that advice. Can you recommend one? From what you are saying, it sounds as if my cheapest solution would be install an inverter/battery UPS which could be connected via a manual change over switch. Could that be achieved via my original suggestion of a Victron inverter and commercial LiFePO4 12v batteries?

 

[jongood]

It doesn’t, it uses grid power when solar is off to amount to the sum, but he is not using all his generation. By introducing batteries in the system, you get to keep what you harvest, and change time of use.

It doesn’t, it uses grid power when solar is off to amount to the sum, but he is not using all his generation. By introducing batteries in the system, you get to keep what you harvest, and change time of use.

One thing I learnt is that having a battery pack doesn't make you immune to power cuts, because they dont want their linesmen electrocuting.

 

[Raul]

One thing I learnt is that having a battery pack doesn't make you immune to power cuts, because they dont want their linesmen electrocuting.

If you have the right system for power cuts, it does disconnect from grid and runs in islanding mode. Think all hospitals and all critical infrastructure has power back up. It runs of batteries until a generator starts up if there is one.

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