'no sell' hybrid roof top solar with batteries

Is there a video or DIY generally instructions for a 'no sell back to grid' roof top solar with batteries system? I have a 1.2kw Legion Solar starter set (no batteries) [https://legionsolar.com/getStarter.html] and though a great system and easy DIY setup, they only sell 150w solar panels and from what I can tell they are not going to upgrade. Well I do not need to put 24 panels on my roof (and I do not have that much space). So I would like to use at least 350w or better panels, 30kwh battery storage and tie to grid when I need them but no sell back. I do not want not pay for hookup to the grid nor monthly rental of meter.
I would be interested in a 'blue print' for something like this. A discussion on 12v, 24v, 48v (if relevant), what kinds of inverter/charge controllers are on the market, etc.

Thank you in advance, I think this type of grid tie (when needed) systems should be a new aspect of 'hybrid' that needs discussion.
Cliff

Are you in the US? You can't have a grid connection and not pay a meter/grid fee.

They way I interpret your above statement, you want 3600w of solar. In 150w panels that would need to be 24 of them. But then you say you don't have the space for 24 panels.

Except for a minor amount of frame space, for the most part the sq foot of 3600w of pannels is the same no matter if they are in 24-150w versions or 10- 360w pannels. So to say you dont have enough space for 24pannels is the same as saying you don't have space for 3600w of solar.

David Poz youtube channel covers how to build DIY ground mount arrays and hook them up to various kinds of all in one inverters and build DIY batteries to power his whole house.

NOTE. if your in any kind of municipality roof mounted panels will require permits which requires a PE signoff on the roof structure. Ground mount panels varry depending on local requirements... Sometimes you can squeek by with no permits, other times you'll have to have a ground mount design that is sealed by a PE.

Minimum design I would consider is a critical loads deisgn with 2-4kw PV with a 3kw 48v all in one inverter (like growatt) with 280ah of battery.

Obviously if your a cabin in the woods the above might be a full cabin power system....if your a new 3500sqft house that is only going to cover the most basic of backup circuits.

I believe the Altestore.com, solar store will do plans. In my state I can have solar and not connect but still need city permits for the electric and pv. You will need 48v and a lot of reading.

CliffSpier said:

Is there a video or DIY generally instructions for a 'no sell back to grid' roof top solar with batteries system? I have a 1.2kw Legion Solar starter set (no batteries) [https://legionsolar.com/getStarter.html] and though a great system and easy DIY setup, they only sell 150w solar panels and from what I can tell they are not going to upgrade. Well I do not need to put 24 panels on my roof (and I do not have that much space). So I would like to use at least 350w or better panels, 30kwh battery storage and tie to grid when I need them but no sell back. I do not want not pay for hookup to the grid nor monthly rental of meter.
I would be interested in a 'blue print' for something like this. A discussion on 12v, 24v, 48v (if relevant), what kinds of inverter/charge controllers are on the market, etc.

Thank you in advance, I think this type of grid tie (when needed) systems should be a new aspect of 'hybrid' that needs discussion.
Cliff

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Hey there Cliff. I'm not a system designer (you can definitely call us as we have them), but a few things - typically the higher the wattage, the larger the panel. There are options here to help you with this issue besides 'ground mounting'. As far as the whole connection thing - are you already grid connected or off grid 100%. Lots of options for either exist, but it's a starting point. There are tons of DIY drawings out there of what people have done. We recently did one for our 5000ES (US) that would likely work for you - but we need a lot more details to help.

CliffSpier said:

, I think this type of grid tie (when needed) systems should be a new aspect of 'hybrid' that needs discussion.

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If you are talking about zero export systems there have been discussions on several threads. It addition most hybrids and many grid tie systems can be configured for zero export.
@fafrd has participated in a lot of threads about external CTs and non export systems.

i think he means a grid-assisted system ( take from grid when needed, just never sell back), and maybe cought up with marketing terms, however as he doesnt want to pay grid connection fees..
i am not sure

@Clifton can you confirm ?

if so, you'll find that mpp-solar, growatts and multitude of others can so exactly what you are looking for

houseofancients said:

if so, you'll find that mpp-solar, growatts and multitude of others can so exactly what you are looking for

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My growatt has been doing this for over a year now just fine. But like I said, you can't be connected to the grid and not pay a meter fee/grid fee.

To clarify your questions. I live in a suburb of a large city connected to city power. Today my 1.2Kw system (no batteries) is connected to the house side of the grid meter (to a 40amp circuit breaker on my house panel). I push no power to the Grid (I have a solar regulator that de-rates the inverters so I do not push power to the grid) but receive Grid power when needed. Since this is a 1.2 Kw starter system I use about 200W from the Grid in a steady state and more when using appliances, etc. My power grid does not know I exist (since I push nothing to them) I have no permits nor Grid-tie power meter.
My desire is to expand this system to handle and average of 30KwH per day including batteries and retain a no push power (no sell power, etc) to the Grid. Also I don't want to expand my current system with the manufacturer I have (Legion Solar) because they only sell 150W panels and I can use less panels if I use 350+w panels. So I need a system (I assume inverter(s)) that will convert solar panels power, manage the batteries and no push power to the grid.
I do not see much discussion or DIY solutions to do that. Either it is Grid-tie or off-grid solutions, not the type of 'hybrid' that I am speaking of.
I would hope this is another avenue for discussion/videos that should be discussed. I just want to buy from the Grid what I need, when I need it and try and be self sufficient for the rest.

As an aside, my brother in CA has a 9.6kW system that is grid tied only (big mistake). And when PG&E brown outs his area, then he has zero power (Becasue he feeds the grid and nothing else), yet he is generating 9.6Kw during the brownout. His solar co, AM Sun Solar, wants multiple $1000s to change his system that he paid $25k for. Not to mention that PG&E does not buy his power at the same rate they charge power at. (I know it's a rip off but nevertheless true - the install contractors and Grid providers act like a casino with odds always favoring the house).

Thank you for all the comments.
Cliff

Sol-ark, and other hybrid inverters can do exactly what you want. I really like the features that Sol-ark offers. But, I just can't justify the cost. They are very proud of what they offer.

There are other hybrid inverters in the $3-4,000 range. I have an Outback Skybox per my signature. The Skybox can be configured for zero export.

CliffSpier said:

As an aside, my brother in CA has a 9.6kW system that is grid tied only (big mistake). And when PG&E brown outs his area, then he has zero power (Becasue he feeds the grid and nothing else), yet he is generating 9.6Kw during the brownout.
Thank you for all the comments.
Cliff

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If you are in a city or it's control area, you are kinda boogered. I may be wrong, but I have never seen a UL approved panel over 350 watt. They do make them over 600, but not approved. If you are insured and troubled about legalese, you are limited in your wattage.
And yeah, I think grid tie is a big mistake.

Yes 350 Watts seems to be the limit but there are thousands of panels to choose from on the CEC list.

If you connect an inverter AC input/output to the house side of the meter, it has to have UL1741 cert to protect utility workers and other customers. One way to isolate might be to have a pure sine inverter that feeds your house from batteries and feed the batteries through a charger fed from the meter. That way you cannot backfeed into the grid and 141 does not apply (since your inverter is not grid-connected). You'll need to consider how the inverter drawing from the batteries interacts with the charger that's feeding the batteries at the same time. Or come up with some way to prevent the two from occurring simultaneously. One way might be to have two banks of batteries, where one is charging while the other is supplying power to the house. There's probably a way to automate the changeover in that case. It might involve two inverters connected in tandem, where you can cut one and the other takes over the full load. Just kinda spitballing here, since I have not tried this or seen it done. Pretty sure that chargers don't like loads drawing from batteries under charge, especially when the batteries are fully drained (i.e., so you're powering your house from a charger through an inverter).

You seem to think they should be able to provide the service and pay Solar people what they pay... Pretty much lost interest after that... Maybe others will walk you thru for free, but I spent some time reading up on how to do what you want to do (its on here). Good luck, have fun.

Surferdudemi said:

You'll need to consider how the inverter drawing from the batteries interacts with the charger that's feeding the batteries at the same time.

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All the battery sees is the net difference. They are just dumb receptacles of power. Likewise after the electrons leave the charger they will follow the path of least resistance so the charger doesn't know or care. All the charger sees is the aggregate load. Your idea of two simple components could be a cost effective solution if one does not want any of the features of a hybrid inverter. One important feature is the ability to switch back to the grid if the batteries get to a set State of Charge. That will prevent ruining your batteries. One set of ruined batteries could pay for one of the less expensive hybrids not mentioned above.

Ampster said:

All the charger sees is the aggregate load.

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That's true. What I am concerned about is how a smart charger is going to react to the varying load. Don't chargers for Li cells have three modes (C-C, C-V, and maintain)? Then you've got the BMS, which has its own settings. How will the charger's software react (and how fast) to a change in voltage due to sudden load, or widely varying load? It would need some testing to explore how a given charger would react. And if the batteries are at the discharge limit (assuming there's a BMS), then the charger has to be able to supply the full load that the inverter could draw.

Surferdudemi said:

That's true. What I am concerned about is how a smart charger is going to react to the varying load. Don't chargers for Li cells have three modes (C-C, C-V, and maintain)?

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It will increase its current if the aggregate loads are not already pulling the full current. Essentially CV is a varying load so that is no different.

Just think about the physics and don't over think or be concerned about a dumb charger that simply responds to loads.
If the BMS can handle the full current of the charger it would not have a problem with less current because some current is going to load and not battery. Similarly if the battery is full all of the output of the charger would go to the loads. If the inverter loads are greater than charger can out put then batteries will discharge to help serve loads.

CliffSpier said:

Is there a video or DIY generally instructions for a 'no sell back to grid' roof top solar with batteries system? I have a 1.2kw Legion Solar starter set (no batteries)

Click to expand...

Is your objective to save money, compared to just buying power from the grid?

Write down the cost of power from grid per kWh,
Estimate the cost of PV + inverter per kWh produced over lifetime of equipment,
Estimate cost of battery (whichever you consider) per kWh over cycle life of battery.

I think batteries generally don't make financial sense, cost more than grid power. They are useful to power critical loads during grid failure, where you don't mind paying a premium price per kWh.

If net metering buy/sell terms aren't attractive, calculate what kW size "no sell back" maximizes your savings.

I looked over the kits they offer - I feel you would be better off putting your own system together. 100 ah battery is not going to store enough power to do much other than lighting. There are 300 ah lithium batteries going for under a grand. I would not start a system with lessthan that!

Thanks Mike

Hedges said:

Is your objective to save money, compared to just buying power from the grid?

Write down the cost of power from grid per kWh,
Estimate the cost of PV + inverter per kWh produced over lifetime of equipment,
Estimate cost of battery (whichever you consider) per kWh over cycle life of battery.

I think batteries generally don't make financial sense, cost more than grid power. They are useful to power critical loads during grid failure, where you don't mind paying a premium price per kWh.

If net metering buy/sell terms aren't attractive, calculate what kW size "no sell back" maximizes your savings.

Click to expand...

I know this is a bit dated, but this calc for the value of the battery is not correct.

The value of the battery is:
X = Price you pay for grid power
Y = Price you get paid for backfeeding the grid
K = KWh per month that you will consume at night that you backfed
(X - Y) * K = Value.
(until you either outrun the extra power produced during the day or outrun the total amount of power used when the panels aren't producing)

When I'm paying 12 cents and getting 4 back, my batteries pay for themselves pretty quickly.