Jim Lee
New Member
I have 11.8Kw of solar panels and I get between 1 and 2 Kw per hour production on cloudy days. As long as it is light you will get some production.
Inverter with off grid capabilities WITHOUT battery
- Thread starter Fardenco
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Yes the electric companies are that way.
Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
Indeed
Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
Well it's true they don't pay much but that's still enough to be worth it as long as I do the installation myself
For 6.5kW of solar panels + supports to mount them + the inverter, the electrical box, cables and everything, I'm at about 5500€
I should be able to sell unused energy for about 0.06€ per kWh, or maybe 0.1€ if I manage to find an electrician who would agree to help me
There is this stupid thing in France, for the main electricity provider to buy your energy, your installation must be done by a certified electrician. You can't do it yourself and then pay someone to verify it. Then your only option is to sell the energy to other providers for cheaper. To be honest I think the 0.1€/kWh is in part paid by the government as some kind of aid, but still. Paying someone to make my installation would cost me easily 3 times as much so that's not worth it
Anyway, selling my surplus is a way for me to justify a bigger installation, more powerful, in the long term it will be more profitable and in the mean time I'll have more panels to work with in the event of a power shortage
timselectric
If I can do it, you can do it.
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If you choose grid tied without battery backup.
When the grid goes down, so do you.
Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
Grid tie using batteries is the way to go if grid power is connected to the house.
1.2. It doesn’t matter if the grid wants your power. There’s limiters on many grid tie inverters that stop power from going into the grid.
3. Using grid tie inverters with limiters does not cost more, in fact a lot less. The inverter and batteries can be sized to only cover the maximum constant loads. Offgrid the inverter and battery needs to be a lot bigger to handle all of the loads.
4. I small offgrid inverter wired to a small critical loads panel is all that needed for the essentials.
Advantages of Grid tie inverter Connected to battery over off-grid inverter for places where grid is available and for people who are experimenting on Lithium batteries to save money at night.
1. No overload.
In case the load exceeds the Grid tie inverters capacity, the Gti will just keep on running at full load. The power shortage will be supplied by the Grid, hence no power failure. Unlike the off grid inverter, The off grid inverter will shutdown in case of overload, hence you have power interruption in your house. Based on my experiences, this is problematic if it happened at night and when I am far away from home. Overload is one of the major cause of off grid inverter failure.
2. High surge current of big inductive loads like aircon and pump is supplied by the grid Because Gti with limiter is slower to react to changes in load current.. While off grid inverter will solely absorb the brunt of surge power, which is also one common cause of inverter failure.
You can use electric drill, grinders and any power tools without stressing your Gti and battery. I had several experiences where welding job was done in the house and the GTI and battery are not stressed out or battery voltage will not drop to a very low level. Off grid inverter , in case of high load starting current, the battery voltage may drop down to a very low level, causing it to shift to grid power prematurely.
3. Most GTI have a low no load loss of about 3-5w. Off grid inverter has about 15-60w no load loss depending on the size of inverter.
4. Off grid inverter max efficiency is about 85%. Grid tie inverters usually have a much higher max efficiency 95%+. When using batteries, this cost a lot of money.
5. To prolong life of inverter, it is a practice not to operate the inverter at max power for a long period of time. This is very hard to do when using off grid inverter, because you don’t have control of how people in your house will use electricity. For GTI, you can easily adjust the max power you want for your GTI
6. When using Off grid inverters for motors and compressor, you have to size it based on surge power . Common to see 3x surge power for off grid inverter. Surge power normally runs for a few milliseconds. So you will be force to buy a large capacity inverter to serve your surge power. While GTI is sized based on your regular load.
Meaning you have to buy off grid inverter atleast twice the power of GTI.
7. In case of inverter breakdown when using off grid inverter, you lost power in your house.
While using a gti no power interruption in your house.
8. Prolonging life of battery-
a. In my personal experiences, high battery temperature is one of
major reason why batteries fail prematurely. Never operate batteries at more than 40degC. Less is better. And you can easily control battery temperature by controlling the discharge current or power. For GTI, this is easy to do because you can easily adjust the current or power discharge by your battery.. Its very hard to control this when using off grid inverter.
During summer months, where ambient temperature can go very high even at night, you can easily adjust battery temperature by reducing further the current or power discharge by your battery.
b. Manufacturer has recommended discharge current rate of batteries to meet the required lifespan specified in their datasheet. For example, If the manufacturer recommended max 10A, then you can easily do this when using GTI consistently. While its very hard to do consistently using off grid inverter.
Bottomline is, use only off grid inverter for emergency or power failure. Power supplies will eventually fail. Make them ready for emergencies. Not for everyday use when grid is available. Use GTI with or without limiters instead which has far more advantages.
No I didn’t come up with all that but I agree with all of it
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Only if there is no sun or if the inverter does not support it (and most of them don't)
But some grid tied inverters are able to provide power from the panels to the house in the event of an outage even without battery, this is precisely what I'm looking for
timselectric
If I can do it, you can do it.
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True, but that's going to cost you more.
It all depends on how much you want to spend.
Sadly all nonsense.
My off hybrid inverter tops up from the grid if more power is required and switches to bypass in overload conditions. Grid tie requires much paperwork and extra expense to comply with the electric company and state rules. Most electric companies require installation by a specialist, no DIY, so that's at least $3000 extra from the get go.
timselectric
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Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
You say ALL non sense but only try to contradict basically one point and that contradiction is wrong
Correct offgrid inverters have to switch to all grid power. Grid tie inverters just keep supplying power and the grid (at the same time) supplies whatever else is needed directly to the loads without any bypass. The grid ties keep running and don’t shutdown when loads exceed the inverters max output. Limiters/cts on the mains stop power from going past your meter. This is for areas that do not allow interconnection/backfeed or areas that have shit payback/credit. Using limiters means you do not need an agreement to comply with the power company. I know this configuration is new so I excuse you for not knowing about it
timselectric
If I can do it, you can do it.
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Some, (including mine) off grid inverters can share the loads with the grid. They power everything that they can and the grid handles the rest. This was the perfect way to ease into solar for me. Very small investment to get started. And then grow my system as funds became available.
Ampster
Renewable Energy Hobbyist
I agree with the sentiment expressed above, but the reality is if you want a UL listed inverter, a GT inverter is the least expensive alternative. I also believe that a GT inverter AC coupled to a hybrid inverter is a less expensive system than just an off grid inverter.
A lot depends on the rates and NEM policy for each area. Ten years ago, when I put in a 3kW GT solar system, I could charge two EVs and use other load shifting strategies consume a Net one mega What hours and still have no bill for power. Today I have a 9 kW system and a hybrid inverter with 42 kWh of batteries and I will have at least a $150 bill because of Minimums and Non Bypassable Charges.
A lot depends on the rates and NEM policy for each area. Ten years ago, when I put in a 3kW GT solar system, I could charge two EVs and use other load shifting strategies consume a Net one mega What hours and still have no bill for power. Today I have a 9 kW system and a hybrid inverter with 42 kWh of batteries and I will have at least a $150 bill because of Minimums and Non Bypassable Charges.
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Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
Right but it (most likely) can only output to a critical/subpanel. So whatever loads are not critical won’t get powered by the inverter or grid while the inverter is on. So to power all the (with an offgrid inverter) home loads they all must be moved to the critical panel. Using a grid tie inverter means all the loads can stay in the main panel and just critical loads moved to subpanel to be rarely powered offgrid. That’s if the home has a grid connection
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timselectric
If I can do it, you can do it.
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There are a lot of variables that go into the right choice for each individual.
Including your end goal.
Utility costs.
Local NEM agreement.
Available space for equipment.
And many other things.
Including your end goal.
Utility costs.
Local NEM agreement.
Available space for equipment.
And many other things.
Cheap 4-life
My body is 2.63 trillion volts, .07v per cell
Even less expensive, a grid tie inverter that can use batteries and a separate small offgrid inverter/charge controller not AC coupled. Just a simple manual transfer switch for rare power outages.
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timselectric
If I can do it, you can do it.
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My end goal is to be completely off grid, and living like I am now.
I'm not going to change my habits.
I don't have to, with the low cost of solar now.
Ampster
Renewable Energy Hobbyist
I think what @timselectric is talking about is a GT inverter configured for Zero Export. It does not need a critical loads panel. It just needs current transformers on the custormer side of the meter so that the GT inverter can throttle back to avoid export. It is an alternative to going through all the paperwork with a utility if the NEM policy is not worth doing all that paperwork.
Ampster
Renewable Energy Hobbyist
I looked at a lot of alternatives but in my environment in California my system (see my signiture) was more cost effective and simpler than all the separate parts you listed. It all depends on where you are standing.
