Sonny Boy inverter battery capability

I have a sunny boy inverter SP 5.0 - isp-us-40. Is it possible to add a battery to receive a charge for night time use with this inverter? Is there some kind of an adapter kit to make this work with a battery?

Sunny Boys like -40 are PV only.
Earlier models had other MPPT algorithms for turbine, etc.

If connected to an HV battery (probably want to use a precharge resistor), they would probably work. Just as people have done with EV connected to PV input of a hybrid.

However, they don't provide charging. SB is just PV --> grid.

SMA sells a couple products for AC coupling SB.

One is Sunny Island (my Avatar picture), which uses 48V battery and includes internal transfer switch for grid. It doesn't really support peak shaving, but can run offgrid, with grid as generator.

The other is Sunny Boy Storage. It looks like SB, but has 3x HV battery inputs. Only select batteries are supported.
I have some SBS 5.1 and a couple LG RESU-10H batteries. A separate transfer switch and auto-transformer lets it work while grid is down.

What is the exact function you want? Store power in battery rather than exporting to grid, and draw from battery rather than importing from grid? I don't think it is because you're on NEM 3.0 (Solar Billing Plan) because an install in the past year or so would have had to be SB -41, not SB -40.

I actually installed the system myself 2 years ago in the summer of 2022 ground mount 10 KW system with two 5 KW sunny boy inverters that I think were built 2018 and never used. I got them new in the original box. I am on NEM 2 pending final approval from the county building inspector. My SEC meter shows that I am on PID 232. And I have given SCE over 10,000 kilowatt hours in the last two years with no compensation or credits. And I'm still getting billed for using the grid at night. And it's pissing me off that they're using me like this. I use about 500 KW per month at night, and I would like to be able to store that in a battery so that I could use that at night. This is my first post on this forum, and you would be welcome to private message me for more details. I just don't know how to private message using this forum yet.

To private message, you click on someone's name, then "Start Conversation".
But the discussion of how to store and use battery power rather than net meter is useful for others.
We can use PM for any more personal data if necessary.

What's holding up final approval from building inspector?
Do you have NEM 2.0 reservation with utility? Because if not, I would think you would be connected under NEM 3.0, "Solar Billing Plan", which is not net metering.

If you have daytime loads like A/C, simply offsetting those is beneficial. Have to evaluate whether cost of battery system for night time consumption is worth additional expense.

Sunny Island with Sunny Boy is very good for offgrid or grid-backup.
What it doesn't appear to support is charging and discharging battery to shave peaks, aiming or zero export.
I and another forum member are in that boat now, about to get pushed onto NEM 3.0 after 20 years of net metering. And we have Sunny Island.

SMA does sell a product for this, Sunny Boy Storage. The basic unit hooks up much like a Sunny Boy, except it gets battery not PV, it uses an external energy meter (WattNode) with CT around wires feeding from utility to your property. It optionally communicates with Sunny Boy.

SBS can charge to reduce or eliminate exports, discharge to reduce or eliminate imports.
An optional "ABU" lets it provide backup when grid is down, for select loads placed downstream of it.

Downsides to SBS include expensive HV batteries, wimpy surge (can't start motors larger than about 2kVA +/-, can't parallel for more power when grid is down.

SI is a powerful, high quality, and expensive inverter, but you can find heavily discounted ones new or slightly used on eBay (due to DC Solar bankruptcy.) It can probably be set up to operate as an off-grid inverter, powering downstream loads from PV and battery, then connecting to grid if battery gets low. If you use it off-grid this way, then your SB won't offset any daytime loads that aren't downstream. It could power your entire house if 56A pass-through and 50A 120/240V from battery is sufficient. 2x SI has 22kVA surge, enough to start 4kVA or so motor.

Officially supported lithium batteries for SI are also expensive, but there are some cheaper commercial batteries (PowerPro) that reportedly work, also DIY.

As I wrote earlier, easiest and cheapest way to use battery is to buy a hybrid that supports a cheap battery and uses CT to sense grid connection.

To answer your question about the nem 2.0 reservation, even though I I selected the power Clerk remain active option, I got an email saying they withdrew my application. Since SCE withdrawal email is a no reply email, I sent a complaint reply to their customer service department, and they never responded. Then I talked to their customer service representative on the phone for probably a good 30 minutes, and the Agents final response was for me just to keep sending emails to their customer service department and they would look into it. They're obviously just giving me the runaround. I told the agent that if I had to eventually I might file a lawsuit, maybe even a class action lawsuit, because I know they're doing this crap to probably thousands of people like me and they're getting free energy from us, and filling us on top of that for our night time usage. So this issue is in limbo right now. This is why I want the battery backup, so they're not sticking me with that extra bill for night time use.

To answer your question about the building inspector hold up, the building inspector does not like my ground mount installation because he has never seen one like it before. He has been pushing me to use an Iron Ridge ground mount system, which as you know is very expensive. I'm in a rural County area and my closest neighbor is a half a mile away. It's not like I'm in a metropolitan subdivision where every house has to look the same. As you know when you look on the internet for ground mount installations, there are thousands of different variations. So the inspector said that he is just going by the national electrical code for solar panels. So when I looked at the National Electric Code for solar panel installations, it's really very simple wording that applies to roof mount and ground mount solar panel installs. It says that the panels shall be securely attached to the surface. It gives no definitions of what the surface is or specifically how they should be attached and with what kind of materials. When I point this out to the building inspector, they just ignore my emails and don't return my phone calls, and they are never available to take a call. I don't want to name any names or even identify the county unless it's in a private message to you, because I don't want their retaliation. My ground Mount system consists of Steel T posts and steel braided cable. Is steel cable is good enough for the San Francisco Golden Gate suspension bridge, it should be good enough for solar panels. And in fact I have even seen steel cable installations for solar panels on the internet. We had a freak winter storm come through here last summer with 60 mph winds, and my solar panels did not budge at all. We don't have hurricanes or tornadoes where I'm at, and the winds rarely get over 10 mph. I don't know if he inspector is in bed with Iron Ridge or Southern California Edison, and it's not worth filing a lawsuit, unless some lawyer or class action lawyer wants to take it on a contingency LOL. I'm sure that Edison is doing this to thousands of their customers LOL

When I installed mine in San Jose 20' years ago, I separated the array into multiple structures each with < 120 sf. footprint and overhanging "eaves" of panels. Now they require much more for ground mount.

If NEM reservation was accepted it might have said they must receive a signed-off building permit by April 14th 2026.
One of mine was in progress, got accepted in the fall of 2023. Another they asked or some updates and I completed it March 2024.

Was your SB -40 accepted? On the pull-down menu of approved inverters at the time?
I do see it on the CEC website, but not all were allowed after some changes July 2020.


The -40 has "N" in some columns where -41 has "Y"

And PG&E hasn't objected to you backfeeding?


But like I said, some hybrid that works with generic 48V LiFePO4 batteries (Or EG4 inverter with their own battery) is probably lowest cost way to do self-consumption.