Hybrid Solar, grid tied solar pv with batteries

The goo they make modern ice cream flavors does not melt anymore, it's mostly just foam and chemicals, so I did not factor the loss of ice cream. But the kegerator would get warm after a couple hours, and that would be bad too.

Solar Tech with batteries is much more mainstream now. In the past, these hybrid systems were complex and batteries were large and messy. Enter Powerwall and their likes.

Solaredge appears to have bridged that gap to only single inverter need. It's the same inverter they use currently on standard PV and in fact they are upgrade pathways for some of existing PV systems.



So the question that I have is why even have a powerwall system for battery source and a large growing segment is Electric Vehicles? 400k Model 3 preorders is a good start of getting huge batteries available to power-shave between 6p-9p demand loads. Why let that battery just sit in the driveway/garage unused?

I've tried looking for a solution to tie-in our EV, but that's just not out there.

Hi gang,

Brand new to the forum here. I recently signed a contract with a local installer for a grid-tied 20kW PV system with battery & generator backup. From the discussion here, seems like I might want to re-consider the battery part.

I was was planning on going with a low kW "peaking" generator to help out the battery during periods when the power's out and there's not much sun. It sounds like I'd be better off spending the money on a higher output generator and skipping the battery altogether for the extended "island" scenario. After reading these posts, it really makes me wonder why they would've proposed battery at all for our residential application...

Hello atebit and welcome to Solar Panel Talk

Depending where you live and what the cost of electricity is a battery system probably will not have a pay back. People in Hawaii might get some type of financial return due to their high cost of electricity but the installation cost of the battery has to be reasonable.

So I believe you having second thoughts is a smart thing.

To me there are only three reasons you might consider battery:

1) If you have very unreliable power, and the blackouts are a weekly problem, then batteries will significantly reduce your generator run time.

2) If you have critical loads (i.e. a server for a business, or a medical device that can't have its power interrupted) then a battery system will function as a UPS and allow continuous power to those systems.

3) If you live in a place where grid tie is legal but backfeed is not (i.e. places like Hawaii) a battery system allows better utilization of solar power.

In general, you're not going to save any money over straight grid once you add batteries due to replacement costs - so you need another reason (like reliable power) to justify them,

I think in your case, all a battery is probably going to achieve for you is uninterrupted loads. You can install no battery and only a generator, a big battery and small generator or a small battery and a big generator. You don't need a battery unless you want the UPS-type of power or need to stretch fuel for some reason.

If you need or want a battery, then you have to find your own sweet spot between generator and battery usage. Bigger generator means more fuel and fuel storage, smaller generator with a battery means less fuel and fuel storage. Batteries aren't cheap or maintenance free, nor is a generator. Both have pros and cons. I personally don't believe that it's generator vs battery, but generator or generator and battery. Battery without a generator is not something I would do unless you have a purpose-built designed to consume only PV power.

If your residential area isn't conducive to fuel storage corresponding to your goals, then a battery might help. For example - if you don't have the ability for large fuel tanks (diesel, propane) because of space, or restrictions, no natural gas service, and you don't want to keep a bunch of fuel in your home/shed/garage/etc, then some battery power might help as it will reduce your fuel needs.

If you decide a battery will be part of the equation, figure out how much time you could have your generator run in the power outage scenario you have in mind. This is a matter of considering the fuel storage you are willing to maintain multiplied by your generators consumption rate. ie. If a generator burned 1gph and you were willing to keep 50g of fuel, then you could run for ~50 hours. Now, is that sufficient for the outages you are planning for? If not, some combination of battery and generator might be helpful.

Most home critical loads can be handled with small UPS systems sized for computers or electronics. Not worth sizing them for large appliances like a refrigerator which can wait for a generator to start up. The only other critical loads would be medical equipment like an oxygen generator. Then you should have something sized by the manufacturer and it should be right next to that equpment.

Thanks for the insightful replies. Nothing super-critical today beyond what a small UPS can handle to bridge the generator start-up & stabilization period.

Time to have a conversation with my contractor, me thinks...

If hybrid allows so much flexibility I really don't understand why people wouldnt want it.

Couldn't you simply get a hybrid inverter without the things that add extra costs like batteries. Justifiable or not the added flexibility is very desirous ( newbie opinion). If the only difference would be in the price of a standard grid tie inverter why not shell out the little bit extra for the added flexibility in case you decide you need another source at a later time? or does going hybrid mean added costs even if you are only connecting PV to it?

The hybrid or bimodal inverter itself costs quite a bit more than non bimodal inverters and almost all of them require batteries. ( storedge being one exception to battery requirement but not cost difference )

we do sell storedge edge systems as battery ready but not that many because you can just get the solaredge se7600 and upgrade it latter if you like to the storedge

Pay your money - take your choice. Just do your homework, get honest estimates for costs, and decide if the time and treasure expense are worth the flexibility gained or enjoyed.

So I basically decided to do what Butch suggested...my contractor is deleting the batteries but designing the system such that battery can be added later.

Does this battery ready solar edge system switch to PV only if the grid goes down during the day?

it can not maintain load if the grid is down though without a battery.


if you add the battery It can be configured for islading ( working without the grid)

The storedge is very capable

Well I was asking because i read one of the shortcomings of grid tie inverter was that you cant use the PV array to power your home if the grid went down. I just wanted to know if the one you mentioned would continue to operate absent of batteries AND should the grid power go out? (during the day of course)