Combine different watt strings question

from what I have read the answer to my question is no, but you all know way more than I do. question is there anything available that will let you combine strings of different watt panels without loosing the efficiency of the larger string? I have a string of 100w panels and would really like to be able to use them with a string of 240w panels

TonyV said:

from what I have read the answer to my question is no, but you all know way more than I do. question is there anything available that will let you combine strings of different watt panels without loosing the efficiency of the larger string? I have a string of 100w panels and would really like to be able to use them with a string of 240w panels

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Micro inverters would take care of it.
You might investigate optimizers.... I don't know if they allow different panels.

Tell us more about your system. Is in battery based?

I am going to be building a new offgrid system to power an rv that I will be staying in a few days a week while a new house is being built,
I think I am going with the EG4-3000 48v AIO and the EG4 48v server rack battery, I currently have 4 100w panels from an old system but that won't be enough to power the new inverter, so I am looking at getting 6 or so 240w panels, just would be nice to use the 100w panels too as they are less than a year old. I am planning to disable the converter in the rv and power everything 12v and 120v with the inverter, that is what I did in a real small camper with the 100w panels. thanks for any advice

TonyV said:

I am going to be building a new offgrid system to power an rv that I will be staying in a few days a week while a new house is being built,
I think I am going with the EG4-3000 48v AIO and the EG4 48v server rack battery, I currently have 4 100w panels from an old system but that won't be enough to power the new inverter, so I am looking at getting 6 or so 240w panels, just would be nice to use the 100w panels too as they are less than a year old. I am planning to disable the converter in the rv and power everything 12v and 120v with the inverter, that is what I did in a real small camper with the 100w panels. thanks for any advice

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What is the Imp Vmp and Voc of both types of panels?

FilterGuy said:

What is the Imp Vmp and Voc of both types of panels?

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current 100w panels, IMP 5.56A, Vmp 18.0v Voc 21.6v
I don't have the new panels yet but i was looking at some blemished ones from san tan
240w IMP 8.03a, Vmp 29.3, Voc 37.2 looking at getting 8 or 10
on a side note, any experience with the used blemished panels? should I stay away from them. still so much to learn

The only thing I can think of is to wire a separate stand-alone MPPT for the 4 100w panels and then hook it directly to the batteries.... but the cost of that may not be worth it.

FilterGuy said:

The only thing I can think of is to wire a separate stand-alone MPPT for the 4 100w panels and then hook it directly to the batteries.... but the cost of that may not be worth it.

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thanks for the replies

FilterGuy said:

The only thing I can think of is to wire a separate stand-alone MPPT for the 4 100w panels and then hook it directly to the batteries.... but the cost of that may not be worth it.

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one more question if you don't mind, why would someone want to go with 230w panels over 250w panels if they are basically the same size and only a couple dollars cheaper per panel? trying to figure out which panels to go with. thanks

Assuming there is not issue with Voc and all else being equal, they probably would not go for the 230W panels unless they are trying to match the panels they already have.

What you are seeing is the dynamic nature of the panel market. The panel market is highly competitive and companies are constantly playing with what they charge. They set a price based on several things:

1) what the panel costs them from the distributor or manufacture. This can cost can vary from one day to the next depending on what is going on with their suppliers.
2) Shipping costs. This too can vary significantly. Shipping costs can vary by season and Sometimes they can get deals from the shippers.
3) Inventory. If they have a large number of the panels, it is capital that is not earning money so they may want to reduce prices to move them out faster. Meanwhile if they don't have a large inventory and the sales are good they may want to increase prices to get a better profit.
4) Old stock. New panels are coming out almost daily that obsoletes old panels. When this happens it becomes harder to sell the old panels so they drop the price
5) New stock. If they have a brand new panel that is hard to get they may want to raise prices.
6) Competition and market dynamics. If there is an overall scarcity or surplus in the market, they will adjust their prices to cut losses or take advantage of opportunities.
7) Quality of panel (Perceived or real). Some panels or panel brands have a better reputation than others. A known brand with a good reputation is going to demand a premium of an identically speced panel from an unknown brand.
8) company health. If a manufacturer or distributor is having a cash-flow issue, they may drop prices to improve their cash flow.

Because of all of these variables, weird inversions can happen in pricing of panels even when buying from the same seller.