Off-grid installation diagram, batteries and other equipment.

Like fellow wizard 1968, he doesn't want to be a milking ox. I want to be completely independent of ZE and its bills (Energa issued me PLN 1,800 for two months of use and I have had a dispute with it before the Energy Regulatory Office for a year). In addition, I am thinking in the long term of an electric car charged from its own power plant, and I do not want to pay further items entitled the power fee is low at the beginning, later it is not known how the salaries of the CEOs of the nuclear power plant, which has not yet been built, are known. I'm talking about black cars. I am thinking about installing a new 3-4 kW photovoltaic as well as a small 2-3 kW wind power plant. I don't have particularly power-hungry devices:
List of devices:
2 laptops, tablet, 2 phones.
Washing machine, fridge, TV, lighting with ordinary light bulbs in the corridors and in the bathroom, LEDs in the rooms.
Aquarium (LED lighting filter, I don't use a heater)
Central heating pumps.
Planning; a garden pump in the summer season, a solar collector for a 120l canister, rather too small than too big, (I have a lot of self-produced wood, so if there is no heat, I can always light a fire).
I am thinking about all 24V panels, optimizers for each panel (elimination of the shading effect and decrease in the efficiency of the entire installation), wires of at least 14mm2, impulse charger to extend battery life, which are probably the most expensive to buy and use. What protection system against deep discharge. I do not know what inverter to buy today, taking into account charging in the future (3-4 years) of the car, what battery, what installation diagram, what charging regulator. The panels are planned to be installed in order to change their position in relation to the sun twice a year in summer and winter. Single-phase installations.
A wind turbine with a vertical axis of rotation would take off in low winds. I would like to thank all companies collecting about PLN 10,000 per day, two jobs for their offers.

You have a strange approach, do you want to spend three times as much on offgrid as you would spend on ongrid in order to wipe the nose of the energy sector? Charging an electric car from batteries is probably a fourfold loss.
I'll tell you this, it won't be cheap when combined with optimizers and a variable panel angle. Not to mention Akku and a good offgrid inverter ...
Think so that you don't have to live twice to get at least the same as in ongrid after 5 years of use...

Added after 1 [minutes]:

With ongrid, I say it's like a car with gas, it has not been profitable for 20 years "in a year it will definitely go up" and somehow it still pays off

Buddy mmichal1981 everyone can dream, start with the simplest first... a piece of paper and a pen... then read a bit about PV, because from what I've read you have little idea about what you wrote.

LiFePO4 is a very good direction in the subject of off-grid batteries, but unfortunately expensive ... 2000-4000 cycles of work is already a reasonable life, incomparable to acids. I myself have a small off-grid 24v 120Ah on an AGM battery with charging from panels + wind turbine and unfortunately I have to worry you. Based on these RES, you will not build a fully autonomous power source (assuming even modest energy needs). There are simply such periods in nature (especially in winter, autumn and early spring) that you get as much sun as a cat cried, e.g. Of course, you can oversize the installation, but firstly, it costs money and secondly, in optimal conditions, you will use a fraction of what the installation can produce, and the rest is wasted ... The situation can be improved by installing a power generator for crisis periods, but this, in turn, will tie you up with other energy suppliers... and the circle closes.

An alternative to the aggregate can be a prepaid meter. But the fact is that this off-grid approach comes with a high price and a lot of limitations. PV planned only to power the house in winter will not do it, even supported by windmills. On the other hand, oversizing means high cost and even lower profitability. Solomon way out of this situation would be to use PV also to heat water in the summer, in winter HUW will come from the boiler. In this way, the power from PV will always be used, and with low water consumption (up to 4 people) it pays off more than the collector. If we manage to mount it in such a way as to change the elevation angle twice a year, let's significantly increase efficiency in winter and who knows, maybe it will work without the unit. However, there is still the issue of costs, they cannot be too high because although sometimes I scare with electricity for PLN 1, it will not be so expensive. 80 groszy per kWh, yes, maybe even in two years, but if off-grid becomes too expensive, even at such kWh prices, the installation will fail faster than it will pay for itself.

There is no point in discussing profitability. Everything loses value after purchase.
The car after leaving the showroom 20-30%. With this approach, it's best to do nothing.
Probably seppuku .
You have ambitions, build it yourself. I have done a sensational work, but it took me quite a long time to refine it, I described a lot in the topic I promoted. Now in the summer with this installation you do not have to look at consumption.
Recently, I bought one new panel, I was changing the configuration of the panel connection. One of the fixes. I was measuring the short-circuit current in relation to what I have.
The measurements came out with a minimal minus difference in relation to my exploited stimulants from Germany.
It's not worth buying new panels at all.
But 7KW of panels is such a minimum and only 50V installation.
The installation must have a real pumping capacity of 3KW for most of the day. So that receivers with a consumption of 2KW work on energy from panels and not from batteries. You turn on the iron plus other small receivers, i.e. 2.5 kW consumption. Shortage of current causes the current to flow from the batteries, let's say about 30A, when the thermostat releases, they will be charged again. Also within an hour, the batteries will complete 40 cycles on the iron.
The second thing is to adapt, you don't turn on heavy receivers at night so as not to torture the batteries. The same on very cloudy days. With me, everyone is used to it and during the day you can go crazy.
I haven't finished my installation yet, but together with the trackers it will have about 16KW. Also, boiling the water boiler will probably not take long . With this power, even on cloudy days there will be no shortage. Auxiliary energy sources will also be added.
After doing this installation, I'm less nervous, usually when I was doing something important on the computer, it was a power failure and a stick in the anthill and I had to use Latin again. No amount of money can compensate for how much nerves these blackouts cost me.

jaskiniowiex wrote:

After doing this installation, I'm less nervous, usually when I was doing something important on the computer, it was a power failure and a stick in the anthill and I had to use Latin again. As much as these blackouts cost me, no amount can compensate for my nerves.

you can buy a decent UPS cheaper and don't use Latin anymore :)

jaskiniowiex wrote:

Le together with trackers it will have about 16KW

The downside in off is that you lose a lot, and with such power it's already a massacre. I had 3.2kW panels connected to a battery of 1240Ah in total - (if they were new) and in such sunny weather a lot of electricity was lost, and on the grid it flies and we will collect it in winter. I would like to add that I do not have power outages, but charged batteries are waiting in case of W ..

hostii wrote:

jaskiniowiex wrote:

After doing this installation, I'm less nervous, usually when I was doing something important on the computer, it was a power failure and a stick in the anthill and I had to use Latin again. As much as these blackouts cost me, no amount can compensate for my nerves.

you can buy a decent UPS cheaper and don't use Latin anymore

And how will the electricity be turned off when there is a cake in the oven? You'll offer your wife to buy a decent UPS so she doesn't use Latin ;)

In some places, power outages are so frequent and disruptive that off-grid becomes justifiable. From time to time, Kuzyn experiences several days of the benefits of living by candlelight combined with throwing out the entire fridge. No discounts are a solution here, even a decent UPS is too weak. Without a really big battery + converter with a power of several kW, nothing will be done. I'm incredibly lucky because even when in 2006 half of Poland was affected by a black out, I had electricity, and in cities a stone's throw away, it wasn't. Probably two or even three years there was no break in supplies, even a few seconds (then one clock is deleted). However, just in case, I prepared such a small system and it came in handy because a year ago there were several short (about 3 hours) but annoying shutdowns. For me, a headache is caused by a lack of electricity when the fireplace is burning because without a working pump, the water in the coil will quickly start to boil. This year, we expanded this microscopic "off grid" with a battery from screwdrivers and trimmers, which gave the possibility of switching the pump to power only from the inverter at almost no cost. On the occasion of PV, I will amortize faster because in the first tariff (the pump runs mainly during the day) I pay over 70 groszy per kWh.

gaz4 wrote:

From time to time, Kuzyn experiences several days of the benefits of living by candlelight combined with throwing out the entire fridge. No discounts are a solution here, even a decent UPS is too weak. Without a really big battery + converter with a power of several kW, nothing will be done

offer him a generator with an autostart, a phase loss sensor

gaz4 wrote:

For me, a headache is caused by a lack of electricity when the fireplace is burning because without a working pump, the water in the coil will quickly start to boil.

for this there is no solution other than UPS + maybe some panel...

after 5 years on off-grid, I can't imagine that someone would turn off my power supply now

The problem is that the unit will work 100 - 200 hours a year, 8 thousand hours will be idle, absorbing time for inspections and maintenance. This means that the purchase cost will never be amortized, unlike PV. An alternative to the PV aggregate for heating water in the boiler (a perfect complement to a solid fuel boiler) + a battery and a solid converter will be more profitable. In the case of a house, apart from the pumps, the fridge is key, so the power must be high (start) but the battery is not very capacious (about 100W during operation). In addition, you can do as I described above, i.e. several not very power-hungry but important devices (central heating pumps, lighting, etc.) are still working on the off grid. In this way, PV works with high efficiency (power utilization) throughout the year, and in winter, PV freed from water heating has a large free power. This allows you to use a battery with a smaller capacity that will not be tortured by deep discharge, so it will last longer. You can easily install an installation with a 10-year return on investment, which is comparable to discounts. But there are no restrictions here, no one orders 3 phases to >3 kW of power, not to mention what will happen in 15 years. This is how long it takes to support prosumers from the moment they are connected to the network, but not longer than until 2035. So if someone wants to enter the on grid, they have little time, after 2020 the amortization time will be less than 15 years and the fun will be less profitable with each passing year. After 2030, only a naive will invest in on grid, it is unlikely that the law will be corrected. Even if PV prices fall, they will never be amortized in 5 years.

You buy such a generator on a well-known portal for 3.5 thousand, power 7 kW immediately with automatic switching, make installations for PLN 3.5, which in winter will provide protection for 8 hours ... I do not negate PV installations, but to do something that makes sense, it is with a budget of 10 thousand you have to start, and with such frequent and long shutdowns, the generator is a more reliable protection. Such a PV installation would have to have a lot of batteries, which entails very large baskets, where it would probably be cool in the summer, but in the winter the installation is only used as a backup, but first of all batteries .... I personally would choose a generator

Indeed, for 3.5 thousand, maybe 1 kW in off grid can be done, but it will be perfectly used 1 kW. In winter there is no such problem with refrigerators because sometimes it is warmer in the freezer than outside - student refrigerators (i.e. food outside the window) will work At this time of the year, the basis is to supply the pumps with CO + lighting, and here PV can easily compete with the aggregate. On the other hand, in summer, the day lasts several hours and even several-day breaks can be survived with a relatively small battery. If for PLN 10,000 I would make, for example, a 2 kW PV with a larger (e.g. 5 kW) inverter and a battery, then in my opinion I can easily survive even a few days without electricity. In winter, the supply of pumps + lighting and consumer electronics / household appliances is secured, and in summer PV provides hot water. It's not the same as a real backup powering everything, but such an installation still works for itself. Even if we assume that it saves mainly coal, i.e. approx. PLN 0.20/kWh, from 2 kW per year we have PLN 400 return on investment. After 20 years, we recover about PLN 6,000, which means its cost becomes comparable to the purchase of the aggregate, and by the way, it will free the owner from the need to shovel coal in hot weather. The unit stands and waits, so it simply cannot amortize itself. Yes, it is convenient, but for the same money we can also free ourselves from the boiler service outside the heating season and that's why I would bet on PV. In the case of coal burners, it is much more convenient.

gaz4 wrote:

In the case of coal burners, it is much more convenient.

Well, there would certainly be some comfort in the summer, but in winter with 1kW, unfortunately, linden. More if he made such an off, typically for heating water, and the converter and batteries were very small (the highest cost) so that he did not have to shovel in the summer
The aggregate or PV would have to make its own decisions when it has the most breaks, as in the summer it is PV as in the winter as the aggregate

gaz4 wrote:

Indeed, for 3.5 thousand, maybe 1 kW in off grid can be done, but it will be perfectly used 1 kW. In winter there is no such problem with refrigerators because sometimes it is warmer in the freezer than outside - student refrigerators (i.e. food outside the window) will work At this time of the year, the basis is to supply the pumps with CO + lighting, and here PV can easily compete with the aggregate. On the other hand, in summer, the day lasts several hours and even several-day breaks can be survived with a relatively small battery. If for PLN 10,000 I would make, for example, a 2 kW PV with a larger (e.g. 5 kW) inverter and a battery, then in my opinion I can easily survive even a few days without electricity. In winter, the supply of pumps + lighting and consumer electronics / household appliances is secured, and in summer PV provides hot water. It's not the same as a real backup powering everything, but such an installation still works for itself. Even if we assume that it saves mainly coal, i.e. approx. PLN 0.20/kWh, from 2 kW per year we have PLN 400 return on investment. After 20 years, we recover about PLN 6,000, which means its cost becomes comparable to the purchase of the aggregate, and by the way, it will free the owner from the need to shovel coal in hot weather. The unit stands and waits, so it simply cannot amortize itself. Yes, it is convenient, but for the same money we can also free ourselves from the boiler service outside the heating season and that's why I would bet on PV. In the case of coal burners, it is much more convenient.

Everything is fine but What do I have the impression that your posts are like persuading to the flat earth theory?
I had offgrid myself, it doesn't pay off at all (unless you live on an island and power up will cost a fortune) and that's why it doesn't pay off that after 2 years almost new 720Ah Akku were suitable for scrap! And no one will convince me that offgrid will ever return.
Only ongrid makes sense and any justification.

Leon444 wrote:

Everything is fine but What do I have the impression that your posts are like persuading to the flat earth theory?
I had offgrid myself, it doesn't pay off at all (unless you live on an island and power up will cost a fortune) and that's why it doesn't pay off that after 2 years almost new 720Ah Akku were suitable for scrap! And no one will convince me that offgrid will ever return.
Only ongrid makes sense and any justification.

That's cool, but you haven't read what we've been discussing lately It's about a situation where there are notorious power outages, sometimes for several days. How does on grid protect against this?

As for the battery, it's a matter of its use. If it is tortured with a large discharge, even a good one will fail after 2-3 years. But when I started my fun in PV I decided to torment the old car battery. Initially, it was only about testing charging from PV, I used radio + LED duffers to discharge. For almost 2 years he was doing quite well despite the terrible charger and the fact that he was barely alive after being removed from the car. When I decided to check its efficiency when powering the pump and some rather power-hungry device, it was discharged too often and too much, so after a few months it finally gave up the ghost. Currently, I have a small gel battery that worked with the radio + LED for a year and stood unused without any charging for another year (I was messing around in my PV a lot then and almost forgot about it) but it still works. Especially supported by the battery from screwdrivers and trimmers, in the winter I will test the power supply to the pump and tell you how it worked. I'm not doing a full off grid at home, I'll just power the key element like a pump + a few little things.

For people who live where the devil says good night and the lines are broken by wind, branches, snow etc, on grid is the worst choice. We supposedly have PV on the roof but if there is no electricity, they are suitable for a doghouse. That is why we started the discussion about the advantage of the generator over PV off grid and as usual there are arguments for and against. I don't like equipment standing and rusting, so I'm leaning towards PV. Who prefers convenience will choose a unit that is switched on 3-4 times a year. The author of the topic thinks about off grid and the comments of each party will certainly help in making a good choice. Personally, when doing off grid, I would never, but never focus only on electricity. IMHO only in cooperation with DHW you will get reasonable results: then you can have high PV power that will work at its maximum capacity all year round.

Armored traction batteries will fail after two years. Probably some drawings.
At the mine, we have such after 10 years of operation and well over 1000 full cycles. Apart from the operating conditions, temperature changes, etc., they still hold and are operated. With a discharge of several percent and good working conditions at home, and systematic cyclical work (the point is that they are not kept discharged for several days) then they sulphate, I suppose that it will last 20 years and 10,000 cycles.
For a battery with a capacity of 840 AH and a 50v installation and an average consumption of 300 watts per house for a few hours at night, it's like if you connected Leda to it.
My battery of batteries does not work with a voltage below 50v after a whole night, and it is nominally 48v.
And they are not new. After a year of use, I added water once. If someone doesn't torture them with ovens and irons at night. It's nothing to be afraid of.

The second issue is misleading with the connection of panels.
Which, according to some people, should be connected so that the voltage is slightly higher than the voltage of the batteries. Then there is the best charging performance. pff. It is still necessary to take into account the drift of the panel voltage depending on the temperature and thus the changing point of the optimal operating point - a trifle.
So how do you combine them???

The topic is stuck, but I repeat the question, because there is no shortage of photovoltaics specialists here.
So how to connect photovoltaic panels in an off-grid installation with a rated voltage of 48v, if the panels have a voltage of 37-38V - i.e. standard? There are only three options. Two, three or four in a row, i.e. 33.3% to get the correct answer. And for what voltage is the MPPT regulator 100 or 150V required. In addition, I will ask for a full justification as to why the other options are completely wrong.

You connect the panels in series/parallel with the maximum voltage and adjust them to the maximum voltage of the regulator that supports the nominal voltage of 48V. So you connect two 38V panels to the regulator with a voltage of up to 100V, because it's up to 78V, the third one may not damage the regulator, but it certainly won't work. I had Cigs for the regulator up to 150V, but one panel is nominally 90V (mppt 64V), so I had them all in parallel because 2 in series gives 160V, which exceeds the nominal value of the regulator.

And what is important, the increase in open-circuit voltage during frost must be taken into account. If the charge regulator has a maximum voltage of 150V, and we connect the PV so that their maximum voltage is 140V, it does not mean that we are in the norm. During heavy -20 degrees frost, poly and monocrystalline panels will have an open circuit voltage higher by up to 15% (in the case of amorphous, less than 10%), i.e. in this case it would be over 160V, more than the max regulator. When I once analyzed the characteristics of regulators, it turned out that the closer to the maximum voltage, the better they work. 150V chargers will work well with 2 or 3 PV poly 24V connected in series (Uoc approx. 40V) but with 3 their efficiency will be higher. And less losses on the cables connecting the PV with the charger.

The correct answer is to connect three panels in series and use only the 150V regulator.
''Gas'' you sort of hit the mark.
When connected four at a time with cold panels, as long as it is charging and the panels are loaded and hot it will be ok. On cold panels (i.e. in winter), if the regulator goes into ''flooat', the voltage will easily exceed 150V, the overvoltage protection will work in the regulator and more will not start. If we turn on a receiver, there will be no charging. The same will be with a 100V regulator and three panels connected in series. If there will be one regulator and the current will be drawn all the time / panels are loaded, it may work and it will not work with a strong installation and several regulators.
Unless someone buys a regulator for a higher voltage, but such are rare.
On the other hand, with two in series, we lose a lot of efficiency.
The regulators maintain the voltage at 55V on the batteries after charging. The optimal operating voltage of two panels is 60V. If the panels are hot, the voltage drops even more. In addition, there is a voltage drop on the regulator (on semiconductor elements, coils, etc. The minimum difference between the input and output voltage must be about 10V, then the MPPT regulator works correctly, optimally and we have maximum efficiency). The effect after switching on the receiver, e.g. 1KW, we first discharge the batteries, the more the voltage on them decreases, the more current will flow from the panels. Great effect. To load them later. Absurd. The efficiency of this system is embarrassing.
It is supposed to work on the principle, I turn on the receiver 1kW - 2kW. The regulator detects the voltage drop and maintains the voltage at 55V by drawing current from the panels. Already in "flooat" mode after charging.
Only when the panels do not work, electricity is drawn from the batteries. For example: vitrons react instantly to changes in battery voltage, dispensing such current from the panels to maintain the voltage at 55V. If we use 300w on a regular basis, the regulator takes 300w from the panels plus the minimum current to maintain the battery voltage after charging. Parameters can of course be changed on the regulators themselves.
The installation always has full power at the moment.

And that's how it's supposed to work. Such basics are hard to find on all these portals.
That's why I asked such a simple question and answered it myself.

Because these are not basics, but nuances Really professional off-grid installations can be counted on the fingers, 12V "toys" rule. There, the PV with the battery is connected directly with a simple charger, and the Umpp voltage of 17V gives a large enough margin for the whole thing to work. The fact that I once read a bit about 100/150V chargers is a complete coincidence because with my off grid I am going in a completely different direction. First of all, I'm starting with high-voltage PV because the priority is DHW and heating the house in the transition period + frying jams in the summer (resistance cookers are perfect for this purpose, and voltage fluctuations from PV do not interfere with anything). PV is supposed to be as cheap as possible so that I don't have to save up single % of efficiency, I can only wave my hand at tens or even hundreds of watts being wasted in the summer. The installation is supposed to pay off, i.e. return after about 10 years at a price of PLN 0.30 per kWh (approximately this is the cost of electricity in the second tariff that replaces PV) and that's enough. I want to power only the pump with the battery + a few small things in the event of a power outage, it's more of a hobby than an attempt to find savings or become independent from monopolists.

At the moment, the maximum voltage of my installation is approx. 200V, but I intend to make some changes after which Uoc will increase to a maximum of 250V during frosts. In fact, they do not predict that much, at the smallest expected load it will be no more than 240V, even in freezing weather. Since battery chargers for such voltages are not popular (i.e. hellishly expensive), I pick my own based on ordinary impulse power supplies. The ones from the Chinese cost pennies, and sometimes they are really good or interesting (one works already at a few V, of course, very low power at the output, but it is also useful ). In addition, equally cheap DC-DC converters and step by step I am implementing off grid from lumber that I already have. E.g. battery for trimmers and screwdrivers. Their basic task is to wait for the "W" hour when, after firing up the fireplace, there is no electricity, which may cause the water in the coil to boil. But I had the hour "w" with a lowercase letter a few times and thanks to this off-grid toy I didn't have to fly around the house in search of a candle and matches

jaskiniowiex wrote:

It is supposed to work on the principle, I turn on the receiver 1kW - 2kW. The regulator detects the voltage drop and maintains the voltage at 55V by drawing current from the panels. Already in "flooat" mode after charging.

I have an E-TRACER ET6415N regulator, probably one of the best available and expensive. To your question, I will answer that it will work so that first the current is taken from the regulator-panels and when the consumption current exceeds the current from the PV, the rest is taken from the battery. Whether the voltage is to be 55V depends on the battery because on my setting boost=56.4V float=54.6 at a temperature of 20 degrees.

Let's say full sun panels can give 2kW, but the batteries are charged and the regulator is charging 500W. When you turn on the 2kW receiver, the voltage on the batteries drops immediately and the regulator immediately reacts and turns up the power as much as necessary / can to obtain boost or float voltage depending on the settings or voltage drop. The regulator that I have e-tracer also reacted that when charging with reduced power of this 500W, when switching on high power consumption, the power went down to zero and increased to max/required.
Of course, I did not allow the charging current to be limited because these are losses, I have a 2x500W/48V heater installed in the DHW and when the voltage reached the set value on the batteries, the heaters turned on in turn

I never exceeded the voltage on it, but the current did because I had 3.6kW of cigs connected to it and it supports up to 3.2kW, only that the cigs have this condition that when they are cooled, they greatly exceed production. After exceeding the current, it immediately turns OFF, but returns to work, only after the 3rd time it will not increase the production, you need to restart the regulator from the power supply. After that, the equipment is a revelation 4 years no-problem

In addition, I have a small 12V on-grid at home, which works in such a way that all mains and 12V sensitive devices work on one power supply connected to the battery, and the epever 4210A regulator with 520W panels is connected in parallel. There is a voltage of 11.5V on the power supply and when even 5W from the panels appears, it immediately consumes less from the network. When the current from the panels exceeds the current of the devices consumed, they charge the battery

hostii wrote:

In addition, I have a small 12V on-grid at home, which works in such a way that all mains and 12V sensitive devices work on one power supply connected to the battery, and the epever 4210A regulator with 520W panels is connected in parallel. There is a voltage of 11.5V on the power supply and when even 5W from the panels appears, it immediately consumes less from the network. When the current from the panels exceeds the current of the devices consumed, they charge the battery

Probably off grid I also tested this type of solution and it is a very good alternative to a PV-powered UPS. As long as there is no power outage, PV current is wasted, which is not a good solution. And with the parallel connection of the batteries and the AC adapter, the voltage is lower than from the battery but higher than the min. needed for the inverter we have a very good compromise. At night, the battery is not tortured by deep discharge, and during the day, PV energy is normally used. I'm thinking about going back to this solution if the pumps were too heavy for my batteries. The best thing is that the role of the regulator is taken over by physics, not some complicated algorithms - that's what I like

gaz4 wrote:

Probably off grid

uh, it's already on-grid because the principle of operation is the same, except that the excess is not given away, but collected
You can do such a thing even without a battery, then one or two panels will be enough, but without a battery there is no protection against power outage.

I'm already getting ready to add panels to 1040W and change the system to 24V, although I have to use a 24V->12V converter, but well

hostii wrote:

In addition, I have a small 12V on-grid at home, which works in such a way that all mains and 12V sensitive devices work on one power supply connected to the battery, and the epever 4210A regulator with 520W panels is connected in parallel. There is a voltage of 11.5V on the power supply and when even 5W from the panels appears, it immediately consumes less from the network. When the current from the panels exceeds the current of the devices consumed, they charge the battery

You should set the power supply voltage higher, e.g. 12.2V, because if you work for a long time without panels, you discharge the battery to zero.

powgreg wrote:

You should set the power supply voltage higher, e.g. 12.2V, because if you work for a long time without panels, you discharge the battery to zero.

It depends, because with a lower voltage of the power supply, more energy can be put into the batteries. If there were frequent power outages from the mains and a longer battery backup would be needed, then the voltage would have to be changed. And even if it discharged to zero once or twice a year, it would not hurt it right away. electricity, sun and me at home, because I also have a generator, I also have an off-grid 48V that remained after switching to on-grid. Just buy some panels and go
But next week it will be 1040W instead of 520W, so in spring, summer the system will be practically independent of the network. The power supply draws 3W when all the electricity comes from the panels / batteries

hostii wrote:

It depends, because with a lower voltage of the power supply, more energy can be put into the batteries. If there were frequent power outages from the mains and you would need longer battery backup, then you would have to change the voltage

But in this case 11.5V it is possible to discharge the battery to zero when there is no PV power despite the presence of the power adapter and mains electricity .

You probably have an oversized installation and treat it as an emergency power supply, so the problem does not occur, but an inexperienced off-grid builder may not notice the problem and quickly kill the batteries.

powgreg wrote:

it is possible to discharge the battery to zero when there is no PV power supply despite the presence of the power supply and mains electricity.

give an example of how to do it...... because when there is no electricity from PV and the voltage on the batteries drops below the planned voltage, all the electricity comes from the power supply, so ...

powgreg wrote:

You probably have an oversized installation and treat it as an emergency power supply, so the problem does not occur, but an inexperienced off-grid builder may not notice the problem and quickly kill the batteries.

I have an oversized one and it's hard so that even on cloudy days it gives something and takes less from the network. The whole system on 12V consumes 140W top - 300W power supply - 520W panels and 1040W in a moment

hostii wrote:

powgreg wrote:

it is possible to discharge the battery to zero when there is no PV power supply despite the presence of the power supply and mains electricity.

give an example of how to do it...... because when there is no electricity from PV and the voltage on the batteries drops below the planned voltage, all the electricity comes from the power supply, so ...

In this case, the current from the battery will stop flowing only when it is completely discharged, i.e. its SEM = 11.5V and the time when it occurs depends on the battery consumption and capacity, in any case, at this voltage, such a parallel connection of the power supply does not protect the battery against excessive discharge.

powgreg you are wrong, the battery will not discharge to the end (10.5V) because the power supply has a higher voltage and the devices draw power first from the generator (device) which has a higher voltage in this case it will be the power supply, you can't get more out of the battery, unless that we will draw more power from the power supply than its nominal power. Then the battery will discharge to zero and the power supply will turn off. You have a similar situation with on-grid, the inverter increases the voltage and first the energy in the house is consumed from PV and when there is no voltage, it drops and is selected from the network where the network is our power supply in this case.