Newbie help with first foray into Solar and need invertor/hybrid advice

[Steve Fractals]

Hi guys,

So like lots of other people, I'm thinking of trying some DIY Solar. My south facing roof is really to small to fit anything other than maybe 2 panels so I thought I'd try with a shed based 2 panel system given that my shed has the same south area as my main roof. I only want to power a tv or radio and a lamp from this initial system but want it grid backed up and auto switched.

I want a system that is mains/grid backed up but I don't want to feed back to the grid as wouldn't have enough spare power anyway and don't want all the hassle of approved systems etc. so whatever system I end up with must have the option to not feed into grid but of course would be nice to have that as a selectable option if possible. I also want a system that I can grow without having to keep swapping out invertors etc. if that's doable.

From my reading it seems I either need a hybrid or a myrid of other separate boxes e.g. invertor and charge controllers etc. am I correct on that?

So my current thinking is some sort of hybrid system but like I said at the moment I plan to start with only 2 X 400watt panels and and some probably lead acid batteries (banks of 2x12v in series to make 24V) (but the option to switch to Lipo etc later on would be good). Again it seems I should be looking at a 24V system (need 230/240 AC output) but I could be completely wrong as a newbie lol.

So what if any hybrid invertor/chargers systems would people recommend that could grow from 2x400 watt panels to say a 3KW system later on (might end up addicted and build a ground based panel system, or would you say stay away from hybrid and go some other route that can still offer grid backup/tie-in?

I absolutely realise that I've still have lots of research to do but any starter guidance even if that's just a link to similar newbie questions would be useful as its a lot to get my head round and would be useful to at least have a good starting point.

 

[Al D]

800W of panels for a TV, radio, and lamp is quite a lot, assuming these are devices from this century (more energy efficient). And remember, the panels will produce power as long as there's usable light. You could reasonably expect to produce 2kWh or more in normal sunlight unless you're near the poles.

You probably don't need to tie into the grid at all for this.

 

[Steve Fractals]

800W of panels for a TV, radio, and lamp is quite a lot, assuming these are devices from this century (more energy efficient). And remember, the panels will produce power as long as there's usable light. You could reasonably expect to produce 2kWh or more in normal sunlight unless you're near the poles.

You probably don't need to tie into the grid at all for this.

Thanks and yes I get that I may have more power from the panels than I will initially use but also will be charging batteries and want to start small. I also realise that probs don't to tie into grid but want a system I can grow with and want it to auto switch to grid usage
(but not feed-in) should I need it without having to switch over manually. I know I could do this with a smaller separate inverter and charger but again I would prefer one box that can connect to grid, charge and power my appliances for solar, batts and then grid and one that is big enough with the correct features that can grow to a bigger system when I'm ready and if poss have the option to charge either deep cycle lead acid or LIPO etc.

 

[MisterSandals]

correct features that can grow to a bigger system when I'm ready and if poss have the option to charge either deep cycle lead acid or LIPO etc.

LIPO (lithium polymer) is the explody lithium ion. Hopefully you mean LiFePO4 - lithium iron phosphate.

In order to build a system that can be expanded, you need to consider whether you are increasing input voltage from the array as well as your overall charging amps. Many of the better solar charge controllers will work with 12/24/48V but its good to know what you're buying in case you need to go from 24V to 48V.

For charge profiles, while many have lithium settings, most folks set their own charging limits using a "user configurable" charge profile. This gives the ultimate flexibility for what battery type and how aggressively you want to charge them.

If you can estimate your anticipated energy needs in terms of watt hours per day, you can get a very good idea of how much battery you will need and how much array you will need to replenish each day. This is the first task of sizing a solar system. If you get these numbers, its pretty easy to size batteries and charge controllers.

 

[solarpowa]

Hey Steve. A possible solution could be a unit like an AC200P, I have one myself and this isn't a promotion for their company and there are other similar types of solar generators out there.

Not sure if you have looked at solar generators yet but they contain everything in one unit such as your solar inverter, batteries and power inverter and you can connect your solar panels direct to them.

That said, there are limitations to them. For example the one I mention above has a limitation of a voltage input of between 35v-150v which for two 400w solar panels should not be an issue but the max solar input it will accept is 700w. This doesn't mean your two 400w panels would not work it just means you may be getting 800w from solar but the unit will only take 700w of it. This essentially means that if you do chose to upgrade your solar in the future then whilst you could still charge this unit it would not be accepting the full amount produced. You can however use solar and a charger in the mains to charge the unit mentioned above at 1200w 700w solar + 500w mains. There are ways to expand the battery capacity on this unit if you look on utube but essentially it is an portable (bit of wieght to it but moveable) all in one and you just run your solar direct to it and run a plug from it to your tv/lamp etc. I used one of these units for over a year just for the purpose of running a tv, lamp, vac and charging devices and ran the solar cable direct from three 285w panels totaling 855w through the old sky cable sockets direct into the front room. Then when I need I take it to the allotment to run the lawnmower, tiller etc. If it needed topping up from the grid then I could just turn the mains charger on and give it a boost, I think I probably had to top up the 2kw battery about 3/4 times in the whole time I used it this way. Now it sits in the kitchen and I run appliances off it then charge it from the solar in the front room with an extension I made to the original cable that now charges an EP500Pro as below.

Again this is not a sales pitch but if you wanted to look into the future there is another unit called an EP500Pro which I also have and purchased to upgrade the battery storage in the front room and this unit can take two solar strings of 1200w each totaling 2.4kw but I still just have it connected to the 855w and it gets the extra 155w on a perfect day (well it gets a bit more but I haven't figured out why yet). I wont go into the pro's and con's of this unit but the reality is it is about 4x times the cost of the AC200P.

If you check my first post on this forum (a couple of days ago) you will see the dilemma I now face from taking this approach.

 

[rodrick]

Mpp lv2424 msd is a good expandable unit to start with 2400 watt inverter 80 amp mppt scc plus 60 amp charger from gen or grid supply with auto transfer switching this is a all in one unit growatt is another unit that’s good starting at about 600.00 a unit for mpp to double capacity just add another unit also go with Lifepo batts if possible more bang for the buck

 

[jvin248]

.

I'm easing into the bath water too... So far my recommendations to consider:

+1 ground mount is best if you have space and can do it. No roof damage, no roof/ladder work, everything is right there.

Just start with a manual switch over -- like using a backup gasoline generator when the grid goes out.

Output limiting factor is the inverter you choose ... 'easy' to add more panels later, easier to manage shading with more panels later too. I'm splitting one array into two arrays for an East and West angled to pick up more power morning and evening giving up mid-day.

String inverter instead of the mini-inverter balancing kind (saves cost)

Inverter listed as "off grid" gives you all the flexibility, a "grid tie" inverter seems to shut people off of solar when the grid is down (which is the primary reason for getting solar in the first place), perhaps there is a workaround but once I saw that I changed inverter strategy to 'off grid'.

Separate battery shed is a good idea, make sure venting is great for lead acid batteries (and maybe for all batteries).

Lithium Iron batteries seem like a great choice for the future.

48V keeps the connection wire sizes smaller and a cheaper wiring system

Many power companies are balking at or reducing rates of selling solar power into the grid. So just plan on your own energy use needs and not trying to build a power farm.

If you have a well pump you'll need a 'split phase' or a pair of inverters to give you two 120v legs to run most deep well water pump motors.

Freight Trucking companies mishandle solar panels during shipping. There are fragile labels and anti-stacking cones on the pallets but I've had fork truck punctures on the main panel shipment and both the main shipment and replacement panel shipments had other products stacked on top, flattening the anti-stacking warning cones.

You might order one of those self-contained portable 'camping' inverter+battery systems to start with. Treat it like a small gasoline generator for rolling black out scenarios. I ordered one of these so I could get started and unluckily during the delivery period we had a power outage across the whole city for days. Would have been handy to have it. The delivery company lists the product as 'delivered' but it was never on my porch. Still working through that with Amazon and the seller.

If doing more than experimenting ... you'll likely need permits with full drawings and plans. Check your local city/township for what they require. A 'stake permit' may allow more flexibility and time for experimenting or gradual building of the system. If you have many closely set neighbors you'll need to pull permits for any substantial system install.

.

 

[Steve Fractals]

Thanks for your replies guys.

So after doing more reading helped by your replies, I now think I basically know at least the items that I require just haven't still yet decided in what package so to speak.

Combiner box should I want more than one string, might need this if I later mount some on the west side but to start just south and maybe now 4x 400w+ panels with 2 being ground based in front of my shed and 2 on shed south roof.

Invertor (with grid tie-in, I say this because I have grid and want the unit to switch to grid power once solar/batts not available), could be a separate invertor or part of a hybrid box. Need to still work out my initial capacity with some growing room, also need to read more on the min startup and if startup should be DC from batts/solar or grid etc. Thinking I need to go 24V to get 220/240V but would 48V be better? Still a bit confused about if I need off=grid or grid tie-in to be honest. So given I want grid to take over and supply my appliances once no Solar or battery available do I need grid tie-in or off grid something like this which is off grid and states cannot output energy to grid. https://www.amazon.co.uk/5-5KW-Hybr...ords=48v+solar+inverter&qid=1662707917&sr=8-7



Solar charger, again separate or part of hybrid box.

Panels, I think I will now go for 4x 400+W panels but still more research needed.

CT or some sort fo zero export meter (as I don't want export as makes life difficult in uk), again more reading and wondering why this zero export isn't built in to hybrid type boxes or am I still missing something? Can I just get any type of CT/meter unit or do I have to get one that is somehow compatible with invertor? Do I even need this is I get an off-grid that can still power load from grid/utility?

Batteries, probs start with Lead Acid (due to price) but still want the option to go LiFePo at a future date.

Associated cabling and mounting clamps etc.

Any guidance on things I've listed or anything I've missed would be great.

 

[solarpowa]

Hey Steve, you could probably get away with an MC4 inline fuse at this stage over the cost of a combiner box. And maybe all together as some solar inverters can take two strings or more. My grid tied inverter has two strings feeding it, 3kw on roof and 1kw on garage, both south facing.

If you have the resources you may consider going to 4x 450w panels totaling 1800w (optimizing your south facing surface, width is the same just the length is a bit longer) instead of 1600w as if you wanted to go to 3kw later using the west roof then it could be 3 x 400w panels at 1200w instead of 4x 350w panels to get the 1400w.

I would personally take another look at Lifpo4 batteries as the lead acid batteries may seem cheaper at first but the DOD/cycles over time will probably come back to bite you in the pocket and you will be outlaying again for batteries in a few years instead of 10+ years. For example my EP500Pro has about 5kw battery storage (it hides 10% to stop me destroying it) but is rated at 6000+ cycles 16.43 years (90% daily discharge/charge) to drop to 80% capacity, and my AC200P is about 2kw (it hides 10% to stop me destroying it) and is rated at 3500+ cycles 9.58 years (90% daily discharge/charge) to 80% capacity both are LifPo4, of course time will tell if they actually do that. Space is also a factor LifPo4 will take up about half the space of lead acid and can be placed in more convenient configurations, I have about 10 x 2v 40ah lead acid batteries in the garage that I got a while back and never used them as by the time I build a box, worry about venting etc and just the sheer amount of space they take up I am just thinking of selling them on.

 

[Steve Fractals]

Hey Steve, you could probably get away with an MC4 inline fuse at this stage over the cost of a combiner box. And maybe all together as some solar inverters can take two strings or more. My grid tied inverter has two strings feeding it, 3kw on roof and 1kw on garage, both south facing.

If you have the resources you may consider going to 4x 450w panels totaling 1800w (optimizing your south facing surface, width is the same just the length is a bit longer) instead of 1600w as if you wanted to go to 3kw later using the west roof then it could be 3 x 400w panels at 1200w instead of 4x 350w panels to get the 1400w.

I would personally take another look at Lifpo4 batteries as the lead acid batteries may seem cheaper at first but the DOD/cycles over time will probably come back to bite you in the pocket and you will be outlaying again for batteries in a few years instead of 10+ years. For example my EP500Pro has about 5kw battery storage (it hides 10% to stop me destroying it) but is rated at 6000+ cycles 16.43 years (90% daily discharge/charge) to drop to 80% capacity, and my AC200P is about 2kw (it hides 10% to stop me destroying it) and is rated at 3500+ cycles 9.58 years (90% daily discharge/charge) to 80% capacity both are LifPo4, of course time will tell if they actually do that. Space is also a factor LifPo4 will take up about half the space of lead acid and can be placed in more convenient configurations, I have about 10 x 2v 40ah lead acid batteries in the garage that I got a while back and never used them as by the time I build a box, worry about venting etc and just the sheer amount of space they take up I am just thinking of selling them on.

Thanks again for the advice.

Sorry about keep asking more but learning as reading replies and also web research etc.


So done more reading and defo now think I need off-grid (as never want export) as it seems these can't do export and I was getting confused because of the way I was thinking of it all being wired. Think I've cleared that up now as follows but please correct me if I'm wrong or tell me if I'm correct.

So (with an electrician) I get the main grid-in removed from my current house consumer/distribution panel and instead get it connected to a separate isolator/breaker box. Feed from this new grid only connected breaker to the AC-in on the invertor so that the only grid connection is to the invertor and grid has been completely disconnected from house load. I then connect panels and batteries to invertor and AC out from invertor goes back to my current house consumer/distribution panel for all my house loads. does that sound right. So with this off-grid invertor there would couldn't possibly be any export and no CT/Meter is needed to prevent export.

Does all that sound right as the basics if I'm using something like the Growatt+SPF5000ES as an example invertor?

 

[solarpowa]

Not sure you want to get the main grid in removed unless you want to be totally off grid without the option of using the grid when no sun or battery storage.

I'm doing something similar to what you are doing for my system but kind of in reverse as my original system was grid tied fitted by an mcs installer in 2016 so I get the generation tariff, feed in tariff as well as being able to use/store what I produce. For example if I generate 100kw then I get paid for 100kw generation tariff then 50% of that is classed as estimated export so get paid for another 50kw export tariff but if I use that 100kw whilst generating or store it in batteries I still get paid for 150kw in tariffs regardless.

This is no longer an option in the UK anymore as if you get it mcs installed and want the feed in tariff then you have to have a smart meter and as far as I am aware you literally only get paid for what you export which is probably pennies, this picture is pretty much how my grid tied system is fitted https://imgs.search.brave.com/ctllj...9t/ZS1zb2xhci1wb3dl/ci1zb2xhci1lbmVy/Z3kuanBn

The bit that says "credit meter" is literally just a meter that counts up how much energy I am generating. The bit that says "Electric meter" is what records how much energy I pull from the grid. If I am generating 1kw of solar and using 2kw of energy then I will be pulling 1kw of energy from the grid to top up to the 2kw usage and the electric meter will record this, if I am generating 2kw of solar and using 2kw of solar then the electric meter will sit stationary, if I am generating 2kw of solar but not using anything then the electric meter will sit stationary and the energy just goes back up the line to the grid and this is where my "credit meter" will be recording everything I generated so I get paid. As it is grid tied, if the grid goes down then I my grid tied system stops working, regardless of how much sun there is, this is sometimes called islanding and stops engineers getting electrocuted up the line on the grid. So this is essentially a basic "grid tied" system.

You could do the above "grid tied" system and fit it yourself (or an electrician) as it basically feeds into the "consumer unit" like any other circuit. But you would not get anything for what you export unless you had it mcs fitted, had a smart meter etc. However you would save on your bills in the same way mentioned above e.g. generating 1kw using 2kw then you would only be pulling 1kw from grid. If you removed yourself from the grid you would be limited to either what you are generating or what you have stored in batteries.

So the bit I am doing similar to you is when I got the grid tied system fitted I paid the fitters to put me an extra 855w solar panels roof mounted on the garage and leave it DC isolated inside the garage with the intention of playing with solar in the future. As time went by I sourced some lead acid batteries for free, purchased cable for wiring them, purchased an off grid TS-MPPT-45 solar inverter (as this met the voltage open circuit VOC requirements of my three panels), the wood to build a battery box and was looking for a reasonable sized DC to AC inverter about 2kw. At the time a couple of years ago a decent one looked like it was going to set me back about £300/£500 and this would have been pretty much all you needed for a basic off grid solar system like the following image https://imgs.search.brave.com/_6jxO...ZWYz/ZWQzNDUxODFlY2M0/ODZmZTlhMWI0NTMy/LmpwZw

Whilst I was looking for the inverter I came across a good deal on an AC200P and thought that does everything I need it has a solar MPPT controller in it, 2kw battery storage and a 2kw pure sinewave inverter and is portable so all I needed to do was literally run my already isolated DC solar cables to the unit and bobs your uncle I have power, and even better moveable power. Not long after this I got invited to join the kickstarter for the EP500Pro so I checked the specs, thought in my head how it would fit (didn't think hard enough) and got one for an absolute bargain.

This is where I started having configuration issues as I now have 7kw of battery storage in a off grid way and im running extension leads to everything to make use of all this stored energy so I started thinking (harder this time round) of how I could use this off grid solar/batteries in all of the house without messing with the grid tied solar and this is where I ended up in this thread with the help of wattmatters https://diysolarforum.com/threads/optimizing-installed-solar-systems-and-adding-batteries.46574/

So if I am understanding you right I think we are trying to achieve the same goal of getting power from the batteries to run things in the house through the main switch board. If so then in that thread you can see the US seem to have a great solution (transfer switch) where you can literally pick a certain amount of circuits and flip them individually over to battery/gen and then back to grid/line as they go. Unfortunately it doesn't look like that is as a simple option for us in the UK and we have a transfer switch but it seems geared to either all circuits, one circuit or a selection of circuits. So we had an electrician out yesterday and he said that if we pick what circuits we want on the transfer then he will put in a consumer unit (you might not need to do this if you already have a modern consumer unit as half our house is on an old push fuse consumer unit that needs replacing, see whattmatters comments in that thread about splitting your consumer unit) with those circuits in and when we flip that switch then "all" of those circuits will then run from the EP500Pro which will have a plug wired to a fuse in the consumer unit in a similar fashion to the basic solar setup above and that will run to the EP500Pro socket/inverter output, essentially as if were plugging a kettle into it but we are actually plugging in all of the selected circuits on the transfer switch. And if the battery starts getting drained too fast, there is not enough solar to charge it back up or we want to have a party then we just flip the transfer switch back and all those circuits are back on the main grid.

You could use that Growatt+SPF5000ES in the way I am trying to utilize my batteries but that inverter is solely for off-grid if I am reading the spec right, you may want to check out some hybrid solar inverters with grid isolation that can offer you the best of all worlds, grid tie, hybrid mode, backup and off-grid, before you make the initial plunge.

 

[Steve Fractals]

.

 

[Steve Fractals]

This is no longer an option in the UK anymore as if you get it mcs installed and want the feed in tariff then you have to have a smart meter and as far as I am aware you literally only get paid for what you export which is probably pennies, this picture is pretty much how my grid tied system is fitted https://imgs.search.brave.com/ctllj...9t/ZS1zb2xhci1wb3dl/ci1zb2xhci1lbmVy/Z3kuanBn

The bit that says "credit meter" is literally just a meter that counts up how much energy I am generating. The bit that says "Electric meter" is what records how much energy I pull from the grid. If I am generating 1kw of solar and using 2kw of energy then I will be pulling 1kw of energy from the grid to top up to the 2kw usage and the electric meter will record this, if I am generating 2kw of solar and using 2kw of solar then the electric meter will sit stationary, if I am generating 2kw of solar but not using anything then the electric meter will sit stationary and the energy just goes back up the line to the grid and this is where my "credit meter" will be recording everything I generated so I get paid. As it is grid tied, if the grid goes down then I my grid tied system stops working, regardless of how much sun there is, this is sometimes called islanding and stops engineers getting electrocuted up the line on the grid. So this is essentially a basic "grid tied" system.

You could do the above "grid tied" system and fit it yourself (or an electrician) as it basically feeds into the "consumer unit" like any other circuit. But you would not get anything for what you export unless you had it mcs fitted, had a smart meter etc. However you would save on your bills in the same way mentioned above e.g. generating 1kw using 2kw then you would only be pulling 1kw from grid. If you removed yourself from the grid you would be limited to either what you are generating or what you have stored in batteries.

So the bit I am doing similar to you is when I got the grid tied system fitted I paid the fitters to put me an extra 855w solar panels roof mounted on the garage and leave it DC isolated inside the garage with the intention of playing with solar in the future. As time went by I sourced some lead acid batteries for free, purchased cable for wiring them, purchased an off grid TS-MPPT-45 solar inverter (as this met the voltage open circuit VOC requirements of my three panels), the wood to build a battery box and was looking for a reasonable sized DC to AC inverter about 2kw. At the time a couple of years ago a decent one looked like it was going to set me back about £300/£500 and this would have been pretty much all you needed for a basic off grid solar system like the following image https://imgs.search.brave.com/_6jxO...ZWYz/ZWQzNDUxODFlY2M0/ODZmZTlhMWI0NTMy/LmpwZw

Whilst I was looking for the inverter I came across a good deal on an AC200P and thought that does everything I need it has a solar MPPT controller in it, 2kw battery storage and a 2kw pure sinewave inverter and is portable so all I needed to do was literally run my already isolated DC solar cables to the unit and bobs your uncle I have power, and even better moveable power. Not long after this I got invited to join the kickstarter for the EP500Pro so I checked the specs, thought in my head how it would fit (didn't think hard enough) and got one for an absolute bargain.

This is where I started having configuration issues as I now have 7kw of battery storage in a off grid way and im running extension leads to everything to make use of all this stored energy so I started thinking (harder this time round) of how I could use this off grid solar/batteries in all of the house without messing with the grid tied solar and this is where I ended up in this thread with the help of wattmatters https://diysolarforum.com/threads/optimizing-installed-solar-systems-and-adding-batteries.46574/

So if I am understanding you right I think we are trying to achieve the same goal of getting power from the batteries to run things in the house through the main switch board. If so then in that thread you can see the US seem to have a great solution (transfer switch) where you can literally pick a certain amount of circuits and flip them individually over to battery/gen and then back to grid/line as they go. Unfortunately it doesn't look like that is as a simple option for us in the UK and we have a transfer switch but it seems geared to either all circuits, one circuit or a selection of circuits. So we had an electrician out yesterday and he said that if we pick what circuits we want on the transfer then he will put in a consumer unit (you might not need to do this if you already have a modern consumer unit as half our house is on an old push fuse consumer unit that needs replacing, see whattmatters comments in that thread about splitting your consumer unit) with those circuits in and when we flip that switch then "all" of those circuits will then run from the EP500Pro which will have a plug wired to a fuse in the consumer unit in a similar fashion to the basic solar setup above and that will run to the EP500Pro socket/inverter output, essentially as if were plugging a kettle into it but we are actually plugging in all of the selected circuits on the transfer switch. And if the battery starts getting drained too fast, there is not enough solar to charge it back up or we want to have a party then we just flip the transfer switch back and all those circuits are back on the main grid.

You could use that Growatt+SPF5000ES in the way I am trying to utilize my batteries but that inverter is solely for off-grid if I am reading the spec right, you may want to check out some hybrid solar inverters with grid isolation that can offer you the best of all worlds, grid tie, hybrid mode, backup and off-grid, before you make the initial plunge.

"Not sure you want to get the main grid in removed unless you want to be totally off grid without the option of using the grid when no sun or battery storage"


Yes I do want the option of using grid when no sun or batt available. It is my understanding when using an off-grid (all in one) that if I remove the grid from my main distribution/consumer unit and feed that grid directly into the invertor AC in and then from AC out to my main districution/comsuer panel then it will use grid if no solar/batt available but cannot export but this is the bit I might be confused about. Looking at the units like the Growatt+SPF5000ES it seems to suggest that if not enough solar/batt then it will combine whatever solar/batt is available with grid from AC in so that would seem to suggest if no solar/batt available then all would be passed to AC out from the grid but again not sure I'm understanding this correctly e.g. solar/batt producing 50% of my requirements so invertor will use that and combine with 50% grid from AC in, or 0% power available from Solor/batts the 100% taken from AC in and distrubuted to AC out.
Do you or anyone know if that's how all in one off-grid invertors like the Growatt+SPF5000ES work?

So has in my diagram below, would I still get power if bat is dead and solar is not producing power but I have AC in connected to my grid with this being the only power in from my grid? b