Alternative use for redundant solar panels

[kipper]

Hey all, looking for peoples thoughts.

I've always been well into alternative energy, I commute to work on a diy solar / wind powered E-bike that has now passed 37,000 miles, the lawns are mowed via the workshop solar system as well as the garden lighting and outbuilding alarms.

Upon my bungalow roof are 3 x sanyo HIT (215W) and 7 x 185W panels that have until today been feeding into the house via a grid tie sunny boy 1200W inverter, we wont go into the morals of this, however today the old spinny wheel leccy meter has been deemed to be out of certificate and replaced with a smart meter rendering the PV panels useless (no MSC certificate).

So, I'm not going to let them go to waste, I'm looking for an alternative and more legitimate way of using the 1200W of power. Sadly I don't have an immersion heater, that would be the obvious choice, I do however from my days of being a marine engineer have a Victron 24V / 2000W sinewave inverter and an Outback Flex80 80A battery charger.

My thoughts are to sell the 1200W sunny boy inverter from the loft as well as the spare and buy a couple of 100Ah lead acid batteries (starting small), charging them and inverting to 240V would be pretty trivial, the biggest issues would be housing the batteries and keeping the inverter close to them (no the lead acid batteries will not be going into the loft!). I would use something like a Victron transfer switch to automatically switch back to mains power when the inverter drops out.

Now, the interesting bit, I want to get the most out of the stored power but obviously there is no way the 2Kw inverter would run the house so would need to install specific sockets. It would be strait forward to fit a DIN mount contactor in the fuse box to switch the lighting circuit between inverter and mains but as all the lights are LED its probably not worth the work as well as wanting to keep the solar inverter system as separate as possible.

I have an electronics workshop outside and an office inside that could run from 100% renewable as long as I stay below 2Kw, if not the transfer switch operates in about 16mS so PC and the like shouldn't notice the difference if the inverter drops out, in theory.

Another option might be to buy more lead acid batteries and fit a storage heater in the workshop.

What are peoples thoughts? anyone doing anything similar?

 

[Jordi]

Well, first of all thanks to introducing me to the ATS. Sounds stupid but you opened me a whole world of possibilities now.
To me your approach seems right by means that you only spend on batteries and reuse all the equipment you already have + the ATS.
That would be the optimal solution If it wasn't for your need to use more than 2kW at once.

To optimize your battery consumption and thus remove that 2kW limit you could buy a hybrid MPPT inverter which theoretically is capable of supplying the necessary power from both battery and grid simultaneously. An advanced user should assist you here because my expectation is the fancy hybrid inverters that can be configured in any kind of way cost half a kidney.

Another possibility is that you adjust your consumption pattern (If possible) to reduce your over-the-2kW moments. What would trigger consumption over 2kW? For how long?

Another idea could be creating a second grid with a cheap 500W or 1000W inverter where you accommodate the heaviest stand-by consumptions to give you more room in the 2000W inverter. Anyway, the starting point is that you will have a power surplus. Running devices directly from the battery also sounds interesting but these DC devices probably consume peanuts compared to the battery size.

Please give us some more info about your consumptions. Interesting case!

 

[SeaGal]

...however today the old spinny wheel leccy meter has been deemed to be out of certificate and replaced with a smart meter rendering the PV panels useless (no MSC certificate).

Not sure I understand your reasoning for the bit in bold?

 

[kipper]

Wow thanks guys, I was expecting to get flamed over this!

My understanding is for the panels to be connected to the grid (via inverter) they need to be installed by an MSC credited installer or the electricity provider will not accept the output and difficult questions will be asked, not such an issue with the old mechanical electric meter which would not grass me up to the supplier and it could tell the difference between importing and exporting.

I did an inverter install on a boat once that used 3 x 3Kw Victron multiplus inverters paralleled together, a huge bank of batteries and a diesel battery charger, I think from memory that would provide 9Kw with 18Kw surge, also the boat could run from 16-32A shore power and would automatically have any shortfall in supply made up from the batteries, how I would love a system like that Prior systems would use a an oversized diesel generator that would stall when the air con fired up!

I'm getting an understanding of my loads now that I've had the smart meter for a couple of weeks, base load seems to be 64 - 180W, so I'm guessing this will be all the VCR's, radios (stuff that we don't really want to turn off) and the fridge and freezer. The big stuff is the kettle, hob, oven, welder and compressor, there is about 4Kw being drawn while her indoors is busy in the kitchen. I'm going to knock up a data logger when I find my CT so I can get a minute by minute reading of power consumption.

An idea I'm kind of looking at is to re-instate the PV / grid tie and use a dump / divert load to stop the smart meter seeing an export, I built a 3 step dump load for a 3KW wind turbine once as these can never be left to run off load, it was pretty cool hearing the turbine tone change as the different loads came in.
The battery charger could run while solar is available, then I could bring in storage heaters, then as a last resort trip the inverter.

I do currently have a second 1200W inverter system running in the workshop, this harvests the sunlight from a single 180W panel and stores it in a 100Ah lead acid battery ready to charge my E-bike when I get home at night, it also runs the lawn mower and charges phones ect.

Something I now realize is that probably 80-90% of what the roof top PV array was generating was being sent out to the grid with very little benefit to me, the battery storage will defiantly be more beneficial. I'm looking at spending a bit more on Lifepo4 batteries as these last longer and are easier to man handle and in the current climate might even pay for themselves (105Ah / 24V seem to be around £500), I just need to find a way to direct the power to the appropriate sockets around the house without creating too much devastation.

 

[SeaGal]

Wow thanks guys, I was expecting to get flamed over this!

& gals

My understanding is for the panels to be connected to the grid (via inverter) they need to be installed by an MSC credited installer or the electricity provider will not accept the output and difficult questions will be asked, not such an issue with the old mechanical electric meter which would not grass me up to the supplier and it could tell the difference between importing and exporting.

You need an MCS certified install if you were getting FIT (pre 2019) or want SEG (post 2020) payments for your export, but is not a requirement for grid connection per se... you just don't get paid the peanuts they pay for exports.

You _will_ require the inverter to be G98 or G99 compliant. You need to inform your DNO of a G98 compliant installation (which covers up to 3680W output) within 30 days of commissioning. If more than 3680W (16A) you need to get permission from the DNO before installation.

I'm getting an understanding of my loads now that I've had the smart meter for a couple of weeks, base load seems to be 64 - 180W, so I'm guessing this will be all the VCR's, radios (stuff that we don't really want to turn off) and the fridge and freezer.

LOL... thought I was the only oldie that still has a VCR. At least mine is a VHS one and not Betamax or a Philips Video 2000 system

Something I now realize is that probably 80-90% of what the roof top PV array was generating was being sent out to the grid with very little benefit to me, the battery storage will defiantly be more beneficial. I'm looking at spending a bit more on Lifepo4 batteries as these last longer and are easier to man handle and in the current climate might even pay for themselves (105Ah / 24V seem to be around £500), I just need to find a way to direct the power to the appropriate sockets around the house without creating too much devastation.

My thoughts... why don't you look at buying a G98 compliant hybrid inverter (to use with 48V LiFePO4) and just grid connect. More flexible than having to re-wire sockets? Just a thought.

 

[Sean Very North]

The old Dimplex storage heaters make fantastic dump loads, the 800w versions are small enough to be hidden almost anywhere. A few smarts sockets + Venus large + a few hours of simple coding and you'll have an all electric central heating system, add an energy meter inline with the incoming tails and you'll have the ingredients of a DIY zero export system.

 

[kipper]

The hybrid inverter makes a lot of sense, that and the batteries would be quite an investment though. I guess the meter tails would feed the inverter, the inverter output would them power the fuse box. I'd obviously have to get a pro in for this bit as it would mean breaking the seal on the company fuse, might be worth getting them to do all the main ac stuff, that way it would all be signed off and official.

I've found this as a starting point;

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid

www.photonicuniverse.com

The PV voltage is very low so would only utilize 4 of the 8 panels, but like I say its only a starting point.

Yes still got a working 1988 JVC VCR. Apparently the V2000 had the best picture, I think the tape was double sided as well. I might have to look into those new fangled DVD things one day

 

[hwy17]

I was expecting to get flamed over this!

We have an electrical safe space here. Quite rare and it's the reason it's my new favorite place on the internet.

 

[SeaGal]

The hybrid inverter makes a lot of sense, that and the batteries would be quite an investment though.

Likely to be around £1000 for the inverter and £1500 for 5kWh of battery.

I guess the meter tails would feed the inverter, the inverter output would them power the fuse box.

Not quite. With "grid-tie" the inverter's AC grid connection just connects in parallel to the incoming supply and your existing loads. Then if you draw more load than the inverter can output at any given time it will just come from the grid.

I'd obviously have to get a pro in for this bit as it would mean breaking the seal on the company fuse, might be worth getting them to do all the main ac stuff, that way it would all be signed off and official.

You need to be part P compliant and work done to BS7671 IET standards. Whether or not you need a sparky in will depend on your existing circuitry, but likely in most cases. Breaking seal on DNO's fuse may not be required if it can be plumbed in via the CU.

I've found this as a starting point;

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid

www.photonicuniverse.com

The PV voltage is very low so would only utilize 4 of the 8 panels, but like I say its only a starting point.

That inverter is off-grid, not grid-tie . I was thinking of something like this one..

RHI-3K-48ES-5G

Solis energy storage inverter is a good choice for on/ off-grid integrated storage solutions 1. Higher incomes: select the electricity consumption mode in real time according to the market price; 2. High independence: can be operated out of the power grid; 3. Higher efficiency: International...

www.ginlong.com

Yes still got a working 1988 JVC VCR. Apparently the V2000 had the best picture, I think the tape was double sided as well. I might have to look into those new fangled DVD things one day

?️

 

[kipper]

Not quite sure what I was thinking there about taking the tails into the inverter, didn't sound right as I wrote it.

The hybrid inverter is definitely the way to go, it would involve pretty much no extra wiring and everything would go in the loft. Originally the plan was for some big lead acid batteries under my office floor but then the inverter would have to be in the immediate vicinity to keep the DC cables short.

The current inverter is on a separate circuit from the consumer unit, I think originally it fed the immersion heater olrigionaly so is probably 2.5mm sq, might have to look at stepping up to 4mm sq depending on the size of inverter I settle on.

I'm part P but only 17th edition so can't sign anything off, but I work with half a dozen people who can.

I might still look at making my outside office / workshop totally off grid just because it has to be done

 

[SeaGal]

The current inverter is on a separate circuit from the consumer unit, I think originally it fed the immersion heater olrigionaly so is probably 2.5mm sq, might have to look at stepping up to 4mm sq depending on the size of inverter I settle on.

If you're going for a G98 compliant inverter then that's max of 16A, so 2.5mm2 T&E would be fine, current-wise.... provided that the distance is not too great - so will need to look at the voltage-rise situation if your grid supply is on the high side.

I'm part P but only 17th edition so can't sign anything off, but I work with half a dozen people who can.

Great - ignore what I put above then... you know that all, already. Sounds like you're good to go then

 

[kipper]

I'm looking at a Solis 3KW hybrid inverter and a single PylonTech US2000 battery, they look like they should come it at a jiff under £2000. Its a lot more than anticipated but I can sell some of my existing bits and the savings should help pay it back.

Its probably one of the smaller scale setups but I've only got 1.2Kw of solar and its a small bungalow so I think it might work out well.

Many thanks for pointing me in the right direction, your help has been invaluable.

 

[SeaGal]

I'm looking at a Solis 3KW hybrid inverter and a single PylonTech US2000 battery, they look like they should come it at a jiff under £2000. Its a lot more than anticipated but I can sell some of my existing bits and the savings should help pay it back.

Its probably one of the smaller scale setups but I've only got 1.2Kw of solar and its a small bungalow so I think it might work out well.

Many thanks for pointing me in the right direction, your help has been invaluable.

do check out Fogstar's battery pack too - more kWh for not much more money. It's a new product, but the owner @Ben@Fogstar is active on here...

See

Help us design a rack-mounted system for the UK

Ben, i think the issue wont just be with the shipping, when they get to their destination, how will someone be able to pick them up and move them? However if you also designed a self build pack of four boxes of cells and one box containing the rack mount (or wall mount?) then it becomes more...

diysolarforum.com

and

Fogstar Energy Server Rack Battery 48V (5.12kWh)

UK-designed Fogstar Energy SR51.2V Lithium (LiFePO4) Server Rack Battery with heating, pre-loaded inverter protocols, LCD touch screen, 16 Grade A EVE Cells, a DC Rated Breaker and an 8 year warranty.

www.fogstar.co.uk

I have no connection with the company apart from being a customer

 

[Jordi]

I'm looking at a Solis 3KW hybrid inverter and a single PylonTech US2000 battery, they look like they should come it at a jiff under £2000. Its a lot more than anticipated but I can sell some of my existing bits and the savings should help pay it back.

Its probably one of the smaller scale setups but I've only got 1.2Kw of solar and its a small bungalow so I think it might work out well.

Many thanks for pointing me in the right direction, your help has been invaluable.

Side question: With an inverter like this, assuming that your battery is small at first and you don't want the inverter pulling more than 1C; can the load applied to the current be limited? (and thus that rest comes from the grid)

Or battery always has to be aligned with inverter max. capabilities?

 

[kipper]

I think a limit can be programmed into the inverter, the battery and inverter communicate over can bus, but this might just be state of charge temperature etc.

Edit. The charge profile seems to be fully configurable but I think that might just be for lead acid / discrete Lithium batteries, I think the battery will likely report its maximum charge / discharge to the inverter over the interface as well as the number of batteries paralleled together, although that's a bit of a guess.

 

[SeaGal]

Edit. The charge profile seems to be fully configurable but I think that might just be for lead acid / discrete Lithium batteries, I think the battery will likely report its maximum charge / discharge to the inverter over the interface as well as the number of batteries paralleled together, although that's a bit of a guess.

Good guesses
With the user-defined battery setting on the Solis, the max charge and discharge rates can be defined. But these can and will be overridden with the CANBus data received by the Solis from the battery's BMS. As you say, the battery will tell the inverter what the max rate shall be.

The little Pylontech should restrict the charge and discharge rate to 25A, which is 0.5C, even if the inverter can handle more. (And it will restrict more when nearly full and/or low temperatures)

 

[kipper]

Talking of low temperatures the heater in the Fogstar unit might be a huge bonus as my loft is well ventilated so gets really cold.

I always add heaters to my e-bike batteries so I can still get to work when its -20 degrees. Brrr.

 

[SeaGal]

Talking of low temperatures the heater in the Fogstar unit might be a huge bonus as my loft is well ventilated so gets really cold.

I always add heaters to my e-bike batteries so I can still get to work when its -20 degrees. Brrr.

If it was -20 not sure I'd want to get on a bike to go to work