I have two power sources, one is solar panels (DC), another is from grid (AC). Is it possible to combine these two power sources with solar getting higher priority ? By high priority I mean draw power from grid only if solar is not sufficient or absent. Final output is required to be AC  One way would be to convert grid ac to dc, matched to dc output of solar panels, and then some how combine them (with priority for solar) and then convert back to AC.   Grid-tie setup is not possible. Also Grid is too unstable (not available every 3rd or 4th hour) so I am going to need batteries any way. I want to prioritize use of power sources in this way:    Solar Grid Batteries.    So if solar is not sufficient it should tap grid (if available) for deficit power else it should use batteries. I want to minimize cycling of batteries and use only as a last resort.    I have come across a  which supports solar first, then battery and lastly Grid. Manual states that You can set the discharge voltage level of battery at which point it will point back to grid until batteries are fully charged then back to batteries and so on.   Maybe I am being too conservative with cycling of batteries. I would like to know if use of batteries only as a backup is possible given my required priorities.    uses only one source at the a time but I want to use both sources at the same time such that if solar is insufficient, don't turn it off, rather augment it with grid. For example if solar can deliver 2 Amps and I need 5 amps in total, I want a way to be able to draw remaining 3 amps from the grid. And if load requires 2 amps, stop taking from grid. Is it possible ?   For simplification lets assume grid also supplies in DC. Also I have some controller d1 connected with Panels which convert output of panels to 24v dc and another device d2 to convert grid to 24v dc as well. I want to combine d1 and d2 to add currents with above mentioned priorities.
121793
I have a power supply of 5v DC 5Ah and a 12v 2Ah lead battery. I was thinking to make a circuit to switch battery line when power is off. I made a little schema, what i'd have to put instead of switch that i draw?  Here's the circuit schematics I made. Thank you
52659
I am considering a home solar photovoltaic installation, probably 5 kW or so.   The usual configuration around here is with a  and .  But when the grid goes down, the inverter shuts off (to avoid back-feeding into the power grid and electrocuting linemen). We are interested in being able to use the solar when the power goes down (not infrequent in this rural area).   According to the solar installer, the only way it is possible to do this is to also install a battery system like .   The idea is that when the inverter loses the 60 Hz sinewave from the grid it shuts off; the inverter in the PowerWall supplies this sinewave, so the inverter doesn't shut off, and there's also a mechanism to disconnect from the grid. That sounds reasonable.   But the cost is not.  Two PowerWalls would roughy double the cost of the installation.  During outages, we would be satisfied to only have power when the sun shines; this would keep food safe, allow us to draw water, etc.  Electrically, there is no reason this can't be done without the expensive battery system.  All that is necessary is to generate the 60Hz reference for the solar system's inverter, and to disconnect from the grid. Has anyone been able to manage such an installation? Would it be strictly DIY (perhaps feasible as I'm a electrical engineer)?
80148
My question is the following: We have two 220V 20A generators connected in parallel to total power 8.8 kw 220 v 40 A load  is 5.5 ohms I'm interested how each generator sees this load since every generator gives half the power. I put this question because one generator can not see this load like 5.5 ohms because it gives half power to not the full power I would like to have somebody explain it a little bit better because it makes me confused .     simplified question   my question is that since every generator in the parallel circuit gives half power in the ideal case it would mean that the generator 1 that gives 220v 20A that is half the power can not "see" the resistance of 5.5 ohms because if "seen" this resistance he had to give complete current in that case we have two problem generator 1 burned because it is not made for such a current problem two if generator 2 gives the same current then the law on energy conservation is not worth what is absolutely not possible  thanks    The last attempt to explain what I asked is very simple  we have two 220v 20A generators and a load of 5.5 ohms if we connect this resistance to just one generator it exceeds its power because it is 220v and 20 A 4.4 kw and the current at that resistor is 40A which would mean that it exceeds the maximum power of one generator ok if we add another generator then together have enough power to supply load it if we know that every generator gives half power ie 220v and 20A  it is impossible to "see "a resistance of 5.5 ohms
49071
So I'm trying to power 2 of these  together in series. I know that I have to add the voltage of the two lights together and get a resistor that restricts the power to that level. I have a 9V battery and the lights are 3V each. I brand new to all of this, and understand almost nothing, so any help would be appreciated. Can someone help me choose the correct resistor (And how to identify that resistor with the color branding thing) so two of those lights listed above can be wired in series? Thanks!
52457
Imagine I have a 10V battery with a capacity of 1Ahrs connected to a 100 Ohm resistor.  I'll get 0.1A (V/R) at a power of 1W (current x voltage) for a total of 10hrs. As a watt is defined as J/s my battery produces 3,600J (1x60x60) in total.  Now, imagine I get a second, identical battery and connect it in series to the first one. I will effectively have a battery of 20V with a capacity of 2Ahrs, all connected to the same 100 Ohm resistor.  I'll get 0.2A at a power of 4W (current x voltage) for a total of 10hrs. This will generate 14,400J (4x60x60).  So, from doubling my energy source I have quadrupled the energy output!  I've obviously made an error somewhere either in my calculations or conceptual understanding, and I would be most grateful to anyone who could set me right.  Thanks!
38356
I just started learning about electronics and decided to quickly sketch a circuit. When it comes to OP and changing the said circuit into an Ac equivalent, I got stuck. Sorry in advance if this is considered a basic question.
76695
I have two 9 V, 300 mA wallwarts and would like to connect them in series to produce +9 V, 0 V and -9 V. This can be done with two 9 V batteries (as seen below), but can I do this with two non-identical wallwarts?
113860
Can I use a 12 V power supply as the source of electricity for this circuit? And where do I connect the positive/negative of my power supply?  I'm a bit new to this so please understand, thank you.
33129
I have two laptops (same manufacture), with the same type of power connector.  However, the power supplies/transformers are slightly different.    The output on the first laptop's power supply is 15.6&nbsp;V at 8.0&nbsp;A. The output on the second laptop's power supply is 15.6&nbsp;V at 5&nbsp;A.  Clearly the voltages are the same, but the currents are different. I assume the second laptop's power supply can not be used on the first, because it can't supply enough power to the laptop.   However, can the first laptop's power supply be safely used on the second laptop?
65384
I want to make a power DC supply with voltage rating 0-200V. I want it to be a variable power supply with voltage from 1V to 200v. What should be my approach?
65075
Can I run two 5v power packs in parallel to give me more mAh's (Time)? Or will one try and charge the other?    I.E. connect both 5V lines together, both GND lines together to my device
78761
I just purchased .  I'll be installing it in my RV.  Current will be supplied by a 12VDC to 120VAC, 3000W inverter.  I'll be using Single-Pole Type BR breakers.  Here's a picture of the box:    My current understanding is that I must install a grounding bar to the box.  This is my current understanding of how to connect the breaker to the main supply.:    Here is my understanding of how I would wire in new circuits:    Does this look right?  I would really appreciate your help -- I've been beating myself over the head about this.
101668
I ordered a new computer and - as always - I think about upgrading it before it arrives.  I thought about adding another graphics card, which would probably push the current PSU beyond its limits. What measures do I have to take care of to combine the powered rails of the PSUs?  I searched for this question and found no conclusive answer, what I've found so far:   some people strongly advise against it but don't provide a reason "don't risk it, simply buy a more powerful one". the power supplies will probably provide slightly different voltages, this will lead to the more powerful PSU providing most of the initial power until its voltage drops and the second one kicks in, too. some people advise using high current diodes. I have no problem with soldering on the wires of my PSU, but I have not seen any reason why I should do it in the first place and high current diodes are not that cheap, especially because I would need one for each powered rail on each PSU (8-10 pieces) there are some commercial solutions to this, like  which is basically just a relay that switches the other power supplies.   So, can I assume it is safe to connect multiple power supplies to power my hardware?
37475
I've found several answers on switching between an Adapter and a Battery. But I need to autmoatically switch between two batteries. One of them is 'hotplugable'.  Problem: I've got a Solarcell which charges a ~16000mAh Li-Ion battery (BATa). Once in a while, the Solarcell doesn't manage to charge the battery enough. It's crucial that I have 3.0 to 4.1 Volts on my VSYS but the voltage will drop below this value if the Solarcell wasn't able to do its job (cloudy weather, vulcano eruption [joke], dirty cells, etc).  My Plan: I've come up with the idea to feed the VSYS with a additional, hotplugable backup battery (BATb) which does get connected to VSYS if BATa drops below ~3.1v.  So basically I need a Low-Voltage-Cutoff (using a Z-Diode with a Mosfet?) which, when cutoff happens, opens another Mosfet..?         &ndash; Schematic created using   I'm not sure about the selection of M2 and how to wire it, so it will be conductive if M1 won't forward power anymore.  And I know about another electrical problem: Just using a Z-Diode (D1) with M1 will render M1 to something like a resistor, not a switch. I've read, that I could use something like a Shut Reference (i.e. TI's TL43xx). Again I'm not sure how to chose the correct one and how to wire it.
4315
For conversion of AC into pulsating DC we used Rectifiers circuits. But I read somewhere (from a well-known site) that the circuit does not work in ideal condition if I used my first circuit. The second circuit is the correct circuit as per their view ideally in ideal condition.  As I used the first circuit many times but on breadboard only so it adds the resistance of wires so might be it works.But I do not understand the reason behind for that extra resistance actually.  Please share your knowledge regarding this. It will be a great help in clearing my concepts on this topic.
77989
I've got two solar panels set up in series as shown on the below schema. I connect positive on panel A to positive on battery, and negative on panel B to negative on battery. The two panels produce 9V each, and 18V in series on a good sunny day. That's what my multimeter says.    If I disconnect cabling between panels and battery, my multimeter shows that the panels produce about 15V (a bit cloudy today). However, when I connect the cables between panels and battery, my multimeter shows about 12.2V. I believe this is the battery voltage.  Why is it that when I connect my multimeter at point A and B it shows 12.2V (when solar panels are connected to the battery). As you can see on the schema, there's a diode in front of point B. Shouldn't that diode make sure that current from the battery not flows back to the panels?   If this is how it is supposed to work, how do I check the voltage my panels produce when the panels are connected to the battery.
61303
In order to supply more power to a circuit. can you split the power between 2 voltage regulators, in parallel?  Can this overpower one of the Voltage Regulators?